<PAGE>   1
 
                                                                    EXHIBIT 99.1
 
                             LETTER OF TRANSMITTAL
 
                             TO TENDER FOR EXCHANGE
                         10 1/2% SENIOR NOTES DUE 2008
 
                                       OF
 
                              SCHUFF STEEL COMPANY
                                  PURSUANT TO
   
                         PROSPECTUS DATED JULY 21, 1998
    
 
   
 THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME ON AUGUST 28,
  1998, UNLESS EXTENDED. TENDERS OF 10 1/2% SENIOR NOTES DUE 2008 MAY ONLY BE
   WITHDRAWN UNDER THE CIRCUMSTANCES DESCRIBED IN THE PROSPECTUS AND HEREIN.
    
 
                 THE EXCHANGE AGENT FOR THE EXCHANGE OFFER IS:
 
   
                         HARRIS TRUST AND SAVINGS BANK
    
 
   
<TABLE>
<S>                               <C>                                 <C>
By Registered or Certified Mail:  Facsimile, Transmission Number:      By Hand or Overnight Delivery:
 Harris Trust and Savings Bank    (For Eligible Institutions Only)     Harris Trust and Savings Bank
    c/o Harris Trust Company               (212) 701-7636                 c/o Harris Trust Company
          of New York                    Confirm Receipt of                     of New York
         P.O. Box 1010                Facsimile by Telephone:                  88 Pine Street
      Wall Street Station                  (212) 701-7624                        19th Floor
    New York, NY 10268-1010                                                  New York, NY 10005
</TABLE>
    
 
                 PLEASE READ THIS ENTIRE LETTER OF TRANSMITTAL
                    CAREFULLY BEFORE CHECKING ANY BOX BELOW
 
<TABLE>
<S>                                                          <C>                    <C>                    <C>
---------------------------------------------------------------------------------------------------------------------------------
                                            DESCRIPTION OF OUTSTANDING NOTES TENDERED
---------------------------------------------------------------------------------------------------------------------------------
                                                                                                              TOTAL PRINCIPAL
                                                                                                                 AMOUNT OF
                                                                                       TOTAL PRINCIPAL          OUTSTANDING
                                                                                      AMOUNT REPRESENTED       NOTES TENDERED
            NAME(S) AND ADDRESS(ES) OF HOLDER(S)                                      BY CERTIFICATE(S)     (MUST BE IN INTEGRAL
           (PLEASE FILL IN, IF BLANK, EXACTLY AS                                        (IF ENCLOSING           MULTIPLES OF
          NAME(S) APPEAR(S) ON OUTSTANDING NOTES)            CERTIFICATE NUMBER(S)      CERTIFICATES)            $1,000)(A)
---------------------------------------------------------------------------------------------------------------------------------
 
                                                               ---------------------------------------------------------------
 
                                                               ---------------------------------------------------------------
 
                                                               ---------------------------------------------------------------
 
                                                               ---------------------------------------------------------------
 
                                                               ---------------------------------------------------------------
                                                                     Total
---------------------------------------------------------------------------------------------------------------------------------
 (a) Unless indicated in the column labeled "Total Principal Amount of Outstanding Notes Tendered," any tendering Holder of
     Outstanding Notes will be deemed to have tendered the entire aggregate principal amount represented by the column labeled
     "Total Principal Amount Represented by Certificate(s)."
      If the space provided above is inadequate, list the certificate numbers and principal amounts on a separate signed schedule
     and affix the list to this Letter of Transmittal.
      The minimum permitted is $1,000 in principal amount of Outstanding Notes. All other tenders must be integral multiples of
     $1,000.
---------------------------------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>   2
 
   
     THE UNDERSIGNED ACKNOWLEDGES RECEIPT OF THE PROSPECTUS, DATED JULY 21, 1998
(THE "PROSPECTUS"), OF SCHUFF STEEL COMPANY, A DELAWARE CORPORATION (THE
"COMPANY"), RELATING TO THE OFFER (THE "EXCHANGE OFFER") OF THE COMPANY, UPON
THE TERMS AND SUBJECT TO THE CONDITIONS SET FORTH IN THE PROSPECTUS AND HEREIN
AND THE INSTRUCTIONS HERETO, TO EXCHANGE $1,000 PRINCIPAL AMOUNT OF ITS 10 1/2%
SENIOR NOTES DUE 2008 (THE "EXCHANGE NOTES") FOR EACH $1,000 PRINCIPAL AMOUNT OF
ITS OUTSTANDING 10 1/2% SENIOR NOTES DUE 2008 (THE "OUTSTANDING NOTES"), OF
WHICH $100 MILLION AGGREGATE PRINCIPAL AMOUNT IS OUTSTANDING. THE MINIMUM
PERMITTED TENDER IS $1,000 PRINCIPAL AMOUNT OF OUTSTANDING NOTES, AND ALL OTHER
TENDERS MUST BE IN INTEGRAL MULTIPLES OF $1,000.
    
 
     DELIVERY OF THIS LETTER OF TRANSMITTAL TO AN ADDRESS, OR TRANSMISSION BY
FACSIMILE, OTHER THAN AS SET FORTH ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.
THE INSTRUCTIONS ACCOMPANYING THIS LETTER OF TRANSMITTAL SHOULD BE READ
CAREFULLY BEFORE THIS LETTER OF TRANSMITTAL IS COMPLETED.
 
   
     The Exchange Offer will expire at 5:00 p.m., New York City time, on August
28, 1998 (the "Expiration Date"), unless extended.
    
 
     HOLDERS WHO WISH TO BE ELIGIBLE TO RECEIVE EXCHANGE NOTES PURSUANT TO THE
EXCHANGE OFFER MUST VALIDLY TENDER THEIR OUTSTANDING NOTES TO THE EXCHANGE AGENT
PRIOR TO 5:00 P.M. ON THE EXPIRATION DATE.
 
     This Letter of Transmittal should be used only to exchange the Outstanding
Notes, pursuant to the Exchange Offer as set forth in the Prospectus.
 
     This Letter of Transmittal is to be used (a) if Outstanding Notes are to be
physically delivered to the Exchange Agent or (b) if delivery of Outstanding
Notes is to be made by book-entry transfer to the account maintained by the
Exchange Agent at The Depository Trust Company ("DTC" or the "Book-Entry
Transfer Facility") pursuant to the procedures set forth in the Prospectus under
the caption "The Exchange Offer -- Procedures for Tendering." Delivery of
documents to the Book-Entry Transfer Facility does not constitute delivery to
the Exchange Agent.
 
     Holders whose Outstanding Notes are not available or who cannot deliver
their Outstanding Notes and all other documents required hereby to the Exchange
Agent by 5:00 p.m. on the Expiration Date nevertheless may tender their
Outstanding Notes in accordance with the guaranteed delivery procedures set
forth in the Prospectus under the caption "The Exchange Offer -- Guaranteed
Delivery Procedures." See Instruction 1.
 
     THE EXCHANGE OFFER IS NOT BEING MADE TO (NOR WILL THE SURRENDER OF
OUTSTANDING NOTES FOR EXCHANGE BE ACCEPTED FROM OR ON BEHALF OF) HOLDERS IN ANY
JURISDICTION IN WHICH THE MAKING OR ACCEPTANCE OF THE EXCHANGE OFFER WOULD NOT
BE IN COMPLIANCE WITH THE LAWS OF SUCH JURISDICTION.
 
     All capitalized terms used herein and not defined herein shall have the
meanings ascribed to them in the Prospectus.
 
     HOLDERS WHO WISH TO EXCHANGE THEIR OUTSTANDING NOTES MUST COMPLETE ALL THE
COLUMNS IN THE BOX ENTITLED "DESCRIPTION OF OUTSTANDING NOTES TENDERED" ON THE
PRIOR PAGE, COMPLETE THE BOX BELOW ENTITLED "METHOD OF DELIVERY" AND SIGN WHERE
INDICATED BELOW.
 
     THE UNDERSIGNED, BY COMPLETING THE BOX ENTITLED "DESCRIPTION OF OUTSTANDING
NOTES TENDERED" AND SIGNING THIS LETTER OF TRANSMITTAL, WILL BE DEEMED TO HAVE
TENDERED THE OUTSTANDING NOTES AND MADE CERTAIN REPRESENTATIONS DESCRIBED IN THE
PROSPECTUS AND HEREIN.
 
                                        2
<PAGE>   3
 
                               METHOD OF DELIVERY
 
[ ]  CHECK HERE IF CERTIFICATES FOR TENDERED OUTSTANDING NOTES ARE ENCLOSED
     HEREWITH.
 
[ ]  CHECK HERE IF TENDERED OUTSTANDING NOTES ARE BEING DELIVERED BY BOOK-ENTRY
     TRANSFER MADE TO THE ACCOUNT MAINTAINED BY THE EXCHANGE AGENT WITH THE
     BOOK-ENTRY TRANSFER FACILITY AND COMPLETE THE FOLLOWING:
 
     Name of Tendering Institution: __________________________________________
 
     Account Number: ________________   Transaction Code Number: _____________
______________________________________________________________________________
 
[ ]  CHECK HERE IF TENDERED OUTSTANDING NOTES ARE BEING DELIVERED PURSUANT TO A
     NOTICE OF GUARANTEED DELIVERY PREVIOUSLY SENT TO THE EXCHANGE AGENT AND
     COMPLETE THE FOLLOWING (SEE INSTRUCTIONS 1 AND 4):
 
     Name(s) of Registered Holder(s):
     _____________________________________________________________
 
     Window Ticket Number (if any):
     _____________________________________________________________
 
     Date of Execution of Notice of Guaranteed Delivery:
     ___________________________________________________
 
     Name of Eligible Institution which Guaranteed Delivery:
     _______________________________________________________
 
     IF DELIVERED BY THE BOOK-ENTRY TRANSFER FACILITY, PROVIDE THE FOLLOWING
     INFORMATION:
 
     [ ]  The Depository Trust Company
 
     Account Number: _______________   Transaction Code Number: ______________
______________________________________________________________________________

[ ]  CHECK HERE IF YOU ARE A BROKER-DEALER AND WISH TO RECEIVE TEN ADDITIONAL
     COPIES OF THE PROSPECTUS AND COPIES OF ANY AMENDMENTS OR SUPPLEMENTS
     THERETO.
 
Name: _________________________________________________________________________
 
Address: ______________________________________________________________________

 
                    NOTE: SIGNATURES MUST BE PROVIDED BELOW
              PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY
 
                                        3
<PAGE>   4
 
Ladies and Gentlemen:
 
   
     Upon the terms and subject to the conditions of the Exchange Offer, the
undersigned hereby tenders to the Company the principal amount of Outstanding
Notes indicated in the box entitled "Description of Outstanding Notes Tendered."
Subject to, and effective upon, the acceptance for exchange of the Outstanding
Notes tendered hereby, the undersigned hereby irrevocably sells, assigns and
transfers to or upon the order of the Company all right, title and interest in
and to such Outstanding Notes, and hereby irrevocably constitutes and appoints
the Exchange Agent the true and lawful agent and attorney-in-fact of the
undersigned with respect to such Outstanding Notes, with full power of
substitution (such power of attorney being deemed to be an irrevocable power
coupled with an interest) to (a) deliver certificates representing such
Outstanding Notes, and to deliver all accompanying evidences of transfer and
authenticity to or upon the order of the Company upon receipt by the Exchange
Agent, as the undersigned's agent, of the Exchange Notes to which the
undersigned is entitled upon the acceptance by the Company of such Outstanding
Notes for exchange pursuant to the Exchange Offer, (b) receive all benefits and
otherwise to exercise all rights of beneficial ownership of such Outstanding
Notes, all in accordance with the terms of the Exchange Offer, and (c) present
such Outstanding Notes for transfer on the register for such Outstanding Notes.
    
 
     The undersigned acknowledges that prior to this Exchange Offer, there has
been no public market for the Outstanding Notes or the Exchange Notes. If a
market for the Exchange Notes should develop, the Exchange Notes could trade at
a discount from their principal amount. The undersigned is aware that the
Company does not intend to list the Exchange Notes on a national securities
exchange and that there can be no assurance that an active market for the
Exchange Notes will develop.
 
     If the undersigned is not a broker-dealer, the undersigned represents that
it is not engaged in, and does not intend to engage in, a distribution of
Exchange Notes. If the undersigned is a broker-dealer that will receive Exchange
Notes, it represents that the Outstanding Notes to be exchanged for Exchange
Notes were acquired as a result of market-making activities or other trading
activities and it acknowledges that it will deliver a prospectus in connection
with any resale of such Exchange Notes; however, by so acknowledging and by
delivering a prospectus, the undersigned will not be deemed to admit that it is
an "underwriter" within the meaning of the Securities Act.
 
     THE EXCHANGE OFFER IS NOT BEING MADE TO, NOR WILL TENDERS BE ACCEPTED FROM
OR ON BEHALF OF, HOLDERS OF THE OUTSTANDING NOTES IN ANY JURISDICTION IN WHICH
THE MAKING OF THE OFFER OR ACCEPTANCE THEREOF WOULD NOT BE IN COMPLIANCE WITH
THE LAWS OF SUCH JURISDICTION OR WOULD OTHERWISE NOT BE IN COMPLIANCE WITH ANY
PROVISION OF ANY APPLICABLE SECURITY LAW.
 
     The undersigned represents that (a) it is not an "affiliate," as defined
under Rule 405 of the Securities Act, of the Company or any of the Guarantors
(as defined in the Prospectus), (b) it is not engaged in, and does not intend to
engage in, and has no arrangement or understanding with any person to
participate in, a distribution of the Exchange Notes, and (c) it is acquiring
the Exchange Notes in the ordinary course of business.
 
     The undersigned understands and acknowledges that the Company reserves the
right, in its sole discretion, to purchase or make offers for any Outstanding
Notes that remain outstanding subsequent to the Expiration Date or to terminate
the Exchange Offer and, to the extent permitted by applicable law, purchase
Outstanding Notes in the open market, in privately negotiated transactions or
otherwise. The terms of any such purchases or offers will differ from the terms
of the Exchange Offer.
 
     The undersigned hereby represents and warrants that (a) the undersigned
accepts the terms and conditions of the Exchange Offer, (b) the undersigned has
a net long position within the meaning of Rule 14e-4 under the Exchange Act
("Rule 14e-4") equal to or greater than the principal amount of Outstanding
Notes tendered hereby, (c) the tender of such Outstanding Notes complies with
Rule 14e-4 (to the extent that Rule 14e-4 is applicable to such exchange), (d)
the undersigned has full power and authority to tender, exchange, assign and
transfer the Outstanding Notes tendered hereby, and (e) when the same are
accepted for exchange by the Company, the Company will acquire good and
unencumbered title thereto, free and clear of all liens, restrictions, charges
and encumbrances and not subject to any adverse claim or right. The undersigned
will, upon request, execute and deliver any additional documents deemed by the
Exchange Agent
 
                                        4
<PAGE>   5
 
or the Company to be necessary or desirable to complete the sale, assignment and
transfer of the Outstanding Notes tendered hereby.
 
     The undersigned agrees that all authority conferred or agreed to be
conferred by this Letter of Transmittal and every obligation of the undersigned
hereunder shall be binding upon the successors, assigns, heirs, executors,
administrators, trustees in bankruptcy and legal representatives of the
undersigned and shall not be affected by, and shall survive, the death or
incapacity of the undersigned. The undersigned also agrees that, except as
stated in the Prospectus, the Outstanding Notes tendered hereby cannot be
withdrawn.
 
     The undersigned understands that tenders of the Outstanding Notes pursuant
to any one of the procedures described in the Prospectus under the caption "The
Exchange Offer -- Procedures for Tendering" and in the instructions hereto will
constitute a binding agreement between the undersigned and the Company in
accordance with the terms and subject to the conditions of the Exchange Offer.
 
     The undersigned understands that by tendering Outstanding Notes pursuant to
one of the procedures described in the Prospectus and the instructions thereto,
the tendering holder will be deemed to have waived the right to receive any
payment in respect of interest on the Outstanding Notes accrued up to the date
of issuance of the Exchange Notes.
 
     The undersigned recognizes that, under certain circumstances set forth in
the Prospectus, the Company may not be required to accept for exchange any of
the Outstanding Notes tendered. Outstanding Notes not accepted for exchange or
withdrawn will be returned to the undersigned at the address set forth below
unless otherwise indicated under "Special Delivery Instructions" below.
 
     Unless otherwise indicated herein under the box entitled "Special Issuance
Instructions" below, Exchange Notes, and Outstanding Notes not validly tendered
or accepted for exchange, will be issued in the name of the undersigned.
Similarly, unless otherwise indicated under the box entitled "Special Delivery
Instructions" below, Exchange Notes, and Outstanding Notes not validly tendered
or accepted for exchange, will be delivered to the undersigned at the address
shown below the signature of the undersigned. The undersigned recognizes that
the Company has no obligation pursuant to the "Special Issuance Instructions' to
transfer any Outstanding Notes from the name of the registered holder thereof if
the Company does not accept for exchange any of the principal amount of such
Outstanding Notes so tendered.
 
     All questions as to the validity, form, eligibility (including time of
receipt), and withdrawal of the tendered Outstanding Notes will be determined by
the Company in its sole discretion, which determination will be final and
binding. The Company reserves the absolute right to reject any and all
Outstanding Notes not properly tendered or any Outstanding Notes the Company's
acceptance of which would, in the opinion of counsel for the Company, be
unlawful. The Company also reserves the right to waive any irregularities or
conditions of tender as to particular Outstanding Notes. The Company's
interpretation of the terms and conditions of the Exchange Offer (including the
instructions in this Letter of Transmittal) will be final and binding. Unless
waived, any defects or irregularities in connection with tenders of Outstanding
Notes must be cured within such time as the Company shall determine. Neither the
Company, the Exchange Agent nor any other person shall be under any duty to give
notification of defects or irregularities with respect to tenders of Outstanding
Notes, nor shall any of them incur any liability for failure to give such
notification. Tenders of Outstanding Notes will not be deemed to have been made
until such irregularities have been cured or waived. Any Outstanding Notes
received by the Exchange Agent that are not properly tendered and as to which
the defects or irregularities have not been cured or waived will be returned
without cost to such holder by the Exchange Agent to the tendering holders of
Outstanding Notes, unless otherwise provided in this Letter of Transmittal, as
soon as practicable following the Expiration Date.
 
                                        5
<PAGE>   6
 
                                PLEASE SIGN HERE
                   (TO BE COMPLETED BY ALL TENDERING HOLDERS)
 
<TABLE>
<S>                                                       <C>
X _____________________________________________________   _________________________________________________, 1998

X _____________________________________________________   _________________________________________________, 1998
                 SIGNATURE(S) OF OWNER                                              DATE
</TABLE>
 
Area code and Telephone Number ________________________________________________
 
     If a Holder is tendering any Outstanding Notes, this Letter must be signed
by the registered Holder(s) as the name(s) appear(s) on the certificate(s) for
the Outstanding Notes or by any person(s) authorized to become registered
Holder(s) by endorsements and documents transmitted herewith. If signature is by
a trustee, executor, administrator, guardian, officer or other person acting in
a fiduciary or representative capacity, please set forth full title. See
Instruction 3.
 
Name(s):_______________________________________________________________________

_______________________________________________________________________________
                             (PLEASE TYPE OR PRINT)
 

Capacity: _____________________________________________________________________

_______________________________________________________________________________


Address: ______________________________________________________________________

_______________________________________________________________________________
                              (INCLUDING ZIP CODE)

 
                              SIGNATURE GUARANTEE
                         (IF REQUIRED BY INSTRUCTION 3)
 
Signature(s) Guaranteed by an Eligible Institution: ___________________________
                                                      (AUTHORIZED SIGNATURE)

_______________________________________________________________________________
                                    (TITLE)
 
_______________________________________________________________________________
                                (NAME AND FIRM)
 
Dated: ___________________________ , 1998
 
                                        6
<PAGE>   7
 
          ____________________________________________________________
 
                         SPECIAL ISSUANCE INSTRUCTIONS
                         (SEE INSTRUCTIONS 3, 4 AND 6)
 
        To be completed ONLY if certificates for Outstanding Notes in a
   principal amount not exchanged and/or certificates for Exchange Notes are
   to be issued in the name of someone other than the undersigned, or if
   Outstanding Notes are to be returned by credit to an account maintained by
   the Book_Entry Transfer Facility.
 
   Issue (check appropriate box)
   [  ]  Exchange Notes to:
   [  ]  Outstanding Notes to:
 
   Name: ___________________________________________________
                            (PLEASE PRINT)
 
   Address: ________________________________________________
 
            ________________________________________________
                               ZIP CODE
 
            ________________________________________________
                     TAXPAYER IDENTIFICATION NUMBER

 
                        (YOU MUST ALSO COMPLETE
                       SUBSTITUTE FORM W_9 BELOW.)
 
   Credit unaccepted Outstanding Notes tendered by book_entry transfer to:
 
   [  ]  The Depository Trust Company account set forth below
 
          ____________________________________________________________
                              (DTC ACCOUNT NUMBER)
          ============================================================
 
                         SPECIAL DELIVERY INSTRUCTIONS
                         (SEE INSTRUCTIONS 3, 4 AND 6)
 
        To be completed ONLY if certificates for Outstanding Notes in a
   principal amount not exchanged and/or certificates for Exchange Notes are
   to be sent to someone other than undersigned at an address other than that
   shown above.
 
   Deliver (check appropriate box)
   [  ]  Exchange Notes to:
   [  ]  Outstanding Notes to:
 
   Name: ____________________________________________________
                             (PLEASE PRINT)
 
   Address: _________________________________________________
 
            _________________________________________________
                                 ZIP CODE
 
            _________________________________________________
                    TAXPAYER IDENTIFICATION NUMBER
 
                         (YOU MUST ALSO COMPLETE
                       SUBSTITUTE FORM W_9 BELOW.)
 
            _________________________________________________
 
           INSTRUCTIONS FORMING PART OF THE TERMS AND CONDITIONS
                     OF THE OFFER AND THE SOLICITATION
 
     1.  DELIVERY OF THIS LETTER OF TRANSMITTAL AND CERTIFICATES; GUARANTEED
DELIVERY PROCEDURES. To be effectively tendered pursuant to the Exchange Offer,
the Outstanding Notes, together with a properly completed Letter of Transmittal
(or facsimile thereof), duly executed by the registered holder thereof, and any
other documents required by this Letter of Transmittal, must be received by the
Exchange Agent at one of its addresses set forth on the first page of this
Letter of Transmittal. If the beneficial owner of any Outstanding Notes is not
the registered holder, then such person may validly tender his or her
Outstanding Notes only by obtaining and submitting to the Exchange Agent a
properly completed Letter of Transmittal from the registered holder. OUTSTANDING
NOTES SHOULD BE DELIVERED ONLY TO THE EXCHANGE AGENT AND NOT TO THE COMPANY OR
TO ANY OTHER PERSON.
 
                                        7
<PAGE>   8
 
     THE METHOD OF DELIVERY OF OUTSTANDING NOTES AND ALL OTHER REQUIRED
DOCUMENTS TO THE EXCHANGE AGENT IS AT THE ELECTION AND RISK OF THE HOLDER.
 
     SUFFICIENT TIME SHOULD BE ALLOWED TO ASSURE TIMELY DELIVERY TO THE EXCHANGE
AGENT BY 5:00 P.M., NEW YORK CITY TIME, ON THE EXPIRATION DATE.
 
     If a holder desires to tender Outstanding Notes and such holder's
Outstanding Notes are not immediately available or time will not permit such
holder's Letter of Transmittal, Outstanding Notes or other required documents to
reach the Exchange Agent on or before the Expiration Date, such holder's tender
may be effected if:
 
          (a) the tender is made through an Eligible Institution (as defined
     herein);
 
          (b) prior to the Expiration Date, the Exchange Agent receives from
     such Eligible Institution a properly completed and duly executed Notice of
     Guaranteed Delivery (by facsimile transmission, mail or hand delivery)
     setting forth the name and address of the holder of the Outstanding Notes,
     the certificate number or numbers of such Outstanding Notes and the
     principal amount of Outstanding Notes tendered, stating that the tender is
     being made thereby, and guaranteeing that, within three business days after
     the Expiration Date, the Letter of Transmittal (or facsimile thereof)
     together with the certificate(s) representing the Outstanding Notes to be
     tendered in proper form for transfer or a Book-Entry Confirmation, as the
     case may be, and any other documents required by the Letter of Transmittal
     will be deposited by the Eligible Institution with the Exchange Agent; and
 
          (c) such properly completed and executed Letter of Transmittal (or
     facsimile thereof) together with the certificate(s) representing all
     tendered Outstanding Notes in proper form for transfer and all other
     documents required by the Letter of Transmittal are received by the
     Exchange Agent within three business days after the Expiration Date.
 
     2.  WITHDRAWAL OF TENDERS. Tendered Outstanding Notes may be withdrawn at
any time prior to 5:00 p.m., New York City time, on the Expiration Date, unless
previously accepted for exchange.
 
     To be effective, a written or facsimile transmission notice of withdrawal
must (a) be received by the Exchange Agent at one of its addresses set forth on
the first page of this Letter of Transmittal prior to 5:00 p.m., New York City
time, on the Expiration Date, unless previously accepted for exchange, (b)
specify the name of the person who tendered the Outstanding Notes, (c) contain
the description of the Outstanding Notes to be withdrawn, the certificate
numbers shown on the particular certificates evidencing such Outstanding Notes
and the aggregate principal amount represented by such Outstanding Notes and (d)
be signed by the holder of such Outstanding Notes in the same manner as the
original signature appears on this Letter of Transmittal (including any required
signature guarantees) or be accompanied by evidence sufficient to have the
Trustee with respect to the Outstanding Notes register the transfer of such
Outstanding Notes into the name of the holder withdrawing the tender. The
signature(s) on the notice of withdrawal must be guaranteed by an Eligible
Institution unless such Outstanding Notes have been tendered (a) by a registered
holder of Outstanding Notes who has not completed either the box entitled
"Special Issuance Instructions" or the box entitled "Special Delivery
Instructions" on this Letter of Transmittal or (b) for the account of an
Eligible Institution. All questions as to the validity, form and eligibility
(including time of receipt) of such withdrawal notices shall be determined by
the Company, whose determination shall be final and binding on all parties. If
the Outstanding Notes to be withdrawn have been delivered or otherwise
identified to the Exchange Agent, a signed notice of withdrawal is effective
immediately upon receipt by the Exchange Agent of a written or facsimile
transmission notice of withdrawal even if physical release is not yet effected.
In addition, such notice must specify, in the case of Outstanding Notes tendered
by delivery of certificates for such Outstanding Notes, the name of the
registered holder (if different from that of the tendering holder) to be
credited with the withdrawn Outstanding Notes. Withdrawals may not be rescinded,
and any Outstanding Notes withdrawn will thereafter be deemed not validly
tendered for purposes of the Exchange Offer. However, properly withdrawn
Outstanding Notes may be retendered by following one of the procedures described
under "The Exchange Offer -- Procedures for Tendering" in the Prospectus at any
time on or prior to the applicable Expiration Date.
 
     3.  SIGNATURES ON THIS LETTER OF TRANSMITTAL, BOND POWERS AND ENDORSEMENTS;
GUARANTEE OF SIGNATURES. If this Letter of Transmittal is signed by the
registered holder(s) of the Outstanding Notes tendered hereby, the signature
must correspond exactly with the name(s) as written on the face of the
certificates without any change whatsoever.
 
                                        8
<PAGE>   9
 
     If any Outstanding Notes tendered hereby are owned of record by two or more
joint owners, all such owners must sign this Letter of Transmittal.
 
     If any Outstanding Notes tendered hereby are registered in different names
on several certificates, it will be necessary to complete, sign and submit as
many separate copies of this Letter of Transmittal as there are different
registrations of certificates.
 
     When this Letter of Transmittal is signed by the registered holder or
holders specified herein and tendered hereby, no endorsements of certificates or
separate bond powers are required unless Exchange Notes are to be issued, or
certificates for any untendered principal amount of Outstanding Notes are to be
reissued, to a person other than the registered holder.
 
     If this Letter of Transmittal is signed by a person other than the
registered holder(s) of any certificate(s) specified herein, such
certificates(s) must be endorsed or accompanied by appropriate bond powers, in
either case signed exactly as the name(s) of the registered holder(s) appear(s)
on the certificate(s).
 
     If this Letter of Transmittal or a Notice of Guaranteed Delivery or any
certificates or bond powers are signed by trustees, executors, administrators,
guardians, attorneys-in-fact, officers of corporations or others acting in a
fiduciary or representative capacity, such persons should so indicate when
signing, and unless waived by the Company, evidence satisfactory to the Company
of their authority so to act must be submitted with this Letter of Transmittal.
 
     Except as described below, signatures on this Letter of Transmittal or a
notice of withdrawal, as the case may be, must be guaranteed by an Eligible
Institution. Signatures on this Letter of Transmittal or a notice of withdrawal,
as the case may be, need not be guaranteed if the Outstanding Notes tendered
pursuant hereto are tendered (a) by a registered holder of Outstanding Notes who
has not completed either the box entitled "Special Issuance Instructions" or the
box entitled "Special Delivery Instructions" on this Letter of Transmittal or
(b) for the account of an Eligible Institution. In the event that signatures on
this Letter of Transmittal or a notice of withdrawal, as the case may be, are
required to be guaranteed, such guarantee must be by a firm which is a member of
a registered national securities exchange or a member of the National
Association of Securities Dealers, Inc. or by a commercial bank or trust company
having an office or correspondent in the United States (each as "Eligible
Institutions").
 
     Endorsements on certificates for Outstanding Notes or signatures on bond
powers required by this Instruction 3 must be guaranteed by an Eligible
Institution.
 
     4.  SPECIAL ISSUANCE AND DELIVERY INSTRUCTIONS. Tendering holders should
indicate in the applicable box the name and address to which certificates for
Exchange Notes and/or substitute certificates evidencing Outstanding Notes for
the principal amounts not exchanged are to be issued or sent, if different from
the name and address of the person signing this Letter of Transmittal. In the
case of issuance in a different name, the employer identification or social
security number of the person named must also be indicated. If no such
instructions are given, any Outstanding Notes not exchanged will be returned to
the name and address of the person signing this Letter of Transmittal.
 
     5.  TAX IDENTIFICATION NUMBER WITHHOLDING. Federal income tax law of the
United States requires that a holder of Outstanding Notes whose Outstanding
Notes are accepted for exchange provide the Company with the holder's correct
taxpayer identification number, which, in the case of a holder who is an
individual, is his or her social security number, or otherwise establish an
exemption from backup withholding. If the Company is not provided with the
correct taxpayer identification number, the exchanging holder of Outstanding
Notes may be subject to a $50 penalty imposed by the Internal Revenue Service
(the "IRS"). In addition, interest on the Exchange Notes acquired pursuant to
the Exchange Offer may be subject to backup withholding in an amount equal to
31% of any interest payment. If withholding occurs and results in an overpayment
of taxes, a refund may be obtained.
 
     To prevent backup withholding, an exchanging holder of Outstanding Notes
must provide his correct taxpayer identification number by completing the
Substitute Form W-9 provided in this Letter of Transmittal, certifying that the
taxpayer identification number provided is correct (or that the exchanging
holder of Outstanding Notes is awaiting a taxpayer identification number) and
that either (a) the exchanging holder has not yet been notified by the IRS that
such holder is subject to backup withholding as a result of failure to report
all interest or dividends or (b) the IRS has notified the exchanging holder that
such holder is no longer subject to backup withholding.
 
                                        9
<PAGE>   10
 
     Certain exchanging holders of Outstanding Notes (including, among others,
all corporations and certain foreign individuals) are not subject to these
backup withholding requirements. A foreign individual and other exempt holders
other than foreign individuals (e.g., corporations) should certify, in
accordance with the enclosed "Guidelines for Certification of Taxpayer
Identification Number on Substitute Form W-9," to such exempt status on the
Substitute Form W-9 provided in this Letter of Transmittal. Foreign individuals
should complete and provide Form W-8 to indicate their foreign status.
 
     6.  TRANSFER TAXES. Holders tendering pursuant to the Exchange Offer will
not be obligated to pay brokerage commissions or fees or to pay transfer taxes
with respect to their exchange under the Exchange Offer unless the box entitled
"Special Issuance Instructions" in this Letter of Transmittal has been
completed, or unless the Exchange Notes are to be issued to any person other
than the holder of the Outstanding Notes tendered for exchange. The Company will
pay all other charges or expenses in connection with the Exchange Offer. If
holders tender Outstanding Notes for exchange and the Exchange Offer is not
consummated, certificates representing the Outstanding Notes will be returned to
the holders at the Company's expense.
 
     Except as provided in this Instruction 6, it will not be necessary for
transfer tax stamps to be affixed to the certificate(s) specified in this Letter
of Transmittal.
 
     7.  INADEQUATE SPACE. If the space provided herein is inadequate, the
aggregate principal amount of the Outstanding Notes being tendered and the
certificate numbers (if available) should be listed on a separate schedule
attached hereto and separately signed by all parties required to sign this
Letter of Transmittal.
 
     8.  PARTIAL TENDERS. Tenders of Outstanding Notes will be accepted only in
integral multiples of $1,000. If tenders are to be made with respect to less
than the entire principal amount of any Outstanding Notes, fill in the total
principal amount of Outstanding Notes which are tendered in the appropriate box
on the cover entitled "Description of Outstanding Notes Tendered." In the case
of partial tenders, new certificates representing the Outstanding Notes in fully
registered form for the remainder of the principal amount of the Outstanding
Notes will be sent to the person(s) signing this Letter of Transmittal, unless
otherwise indicated in the appropriate place on this Letter of Transmittal, as
promptly as practicable after the expiration or termination of the Exchange
Offer.
 
     9.  MUTILATED, LOST, STOLEN OR DESTROYED OUTSTANDING NOTES. Any holder
whose Outstanding Notes have been mutilated, lost, stolen or destroyed should
contact the Exchange Agent at the address indicated above for further
instructions.
 
     10.  REQUEST FOR ASSISTANCE OR ADDITIONAL COPIES. Requests for assistance
or additional copies of the Prospectus or this Letter of Transmittal may be
obtained from the Exchange Agent at its telephone number set forth on the first
page of this Letter of Transmittal.
 
                                       10
<PAGE>   11
 
--------------------------------------------------------------------------------
 
<TABLE>
<S>                                <C>                                                         <C>
                                                          PAYER'S NAME:
=================================================================================================================================
 SUBSTITUTE                         Part 1 -- PLEASE PROVIDE YOUR TIN IN THE BOX AT RIGHT AND
 FORM W-9                           CERTIFY BY SIGNING AND DATING BELOW.                       ------------------------------
 DEPARTMENT OF THE TREASURY                                                                    Social Security Number
 INTERNAL REVENUE SERVICE
                                                                                               or
                                                                                               ------------------------------
                                                                                               Employer Identification
                                                                                               Number
                                   ---------------------------------------------------------------------------------------------
                                    Part 2 -- Certification -- Under penalties of perjury, I
                                    certify that:
                                    (1) The number shown on this form is my correct Taxpayer
                                        Identification Number (or I am waiting for a number to
                                        be issued to me) and
                                    (2) I am not subject to backup withholding because (a) I
                                        am exempt from backup withholding or (b) I have not
                                        been notified by the Internal Revenue Service (the
                                        "IRS") that I am subject to backup as a result of
                                        failure to report all interest or dividends or (c) the
                                        IRS has notified me that I am no longer subject to
                                        backup withholding.
                                   ---------------------------------------------------------------------------------------------
 PAYER'S REQUEST FOR                Certification Instructions -- You must cross out item (2) in Part 2 above if you have been
 TAXPAYER IDENTIFICATION            notified by the IRS that you are subject to backup withholding because of under reporting
 NUMBER (TIN)                       interest or dividends on your tax returns. However, if after being notified by the IRS that
                                    you were subject to backup withholding you received another notification from the IRS stating
                                    that you are no longer subject to backup withholding, do not cross out such item (2). If you
                                    are exempt from backup withholding, check the box in Part 4 above.
 
                                   ---------------------------------------------------------------------------------------------
 
                                    Signature ----------------------------------------- Date------------------------- , 1998
                                   -------------------------------------------------------------------------------------------
                                    Name (Please Print)
---------------------------------------------------------------------------------------------------------------------------------
</TABLE>
 
 Part 3 -- Awaiting TIN [ ]
 
                                                      --------------------------
 
                                                       Part 4 -- Exempt [ ]
 
NOTE: FAILURE TO COMPLETE AND RETURN THIS FORM MAY RESULT IN BACKUP WITHHOLDING
      OF 31% OF ANY PAYMENTS MADE TO YOU PURSUANT TO THE OFFER AND THE
      SOLICITATION PLEASE REVIEW THE ENCLOSED GUIDELINES FOR CERTIFICATION OF
      TAXPAYER IDENTIFICATION NUMBER ON SUBSTITUTE FORM W-9 FOR ADDITIONAL
      DETAILS. YOU MUST COMPLETE THE FOLLOWING CERTIFICATE IF YOU CHECKED THE
      BOX IN PART II OF THE SUBSTITUTE FORM W-9.
 
                                       11
<PAGE>   12
 
                     YOU MUST COMPLETE THE FOLLOWING CERTIFICATE
               IF YOU CHECKED THE BOX IN PART 3 OF SUBSTITUTE FORM W-9
 
                CERTIFICATE OF AWAITING TAXPAYER IDENTIFICATION NUMBER
 
I certify under penalty of perjury that a taxpayer identification number has not
been issued to me, and either (a) I have mailed or delivered an application to
receive a taxpayer identification number to the appropriate Internal Revenue
Service Center or Social Security Administration Office or (b) I intend to mail
or deliver an application in the near future. I understand that if I do not
provide a taxpayer identification number within 60 days, 31% of all reportable
payments made to me thereafter will be withheld until I provide a number.
 
------------------------------------------
                Signature                                                   Date
                                            Date -------------------------, 1998
 
------------------------------------------
           Name (Please Print)
 
                                       12
<PAGE>   13
 
                         NOTICE OF GUARANTEED DELIVERY
                             TO TENDER FOR EXCHANGE
                         10 1/2% SENIOR NOTES DUE 2008
 
                                       OF
 
                              SCHUFF STEEL COMPANY
                                  PURSUANT TO
   
                         PROSPECTUS DATED JULY 21, 1998
    
 
   
     This Notice of Guaranteed Delivery or a form substantially equivalent
hereto must be used to accept the offer (the "Exchange Offer") of Schuff Steel
Company, a Delaware corporation (the "Company"), to exchange $1,000 principal
amount of its 10 1/2% Senior Notes due 2008 for each $1,000 principal amount of
its outstanding 10 1/2% Senior Notes due 2008 (the "Outstanding Notes") if (a)
certificates representing the Outstanding Notes are not immediately available or
(b) time will not permit the Outstanding Notes and all other required documents
to reach the Exchange Agent on or prior to the Expiration Date. This form may be
delivered by an Eligible Institution (as defined) by mail or hand delivery, or
transmitted via facsimile, telegram or telex, to the Exchange Agent as set forth
below. All capitalized terms used herein but not defined herein shall have the
meanings ascribed to them in the Prospectus dated July 21, 1998 (the
"Prospectus").
    
 
     THE EXCHANGE OFFER IS NOT BEING MADE TO (NOR WILL THE SURRENDER OF
OUTSTANDING NOTES BE ACCEPTED FROM OR ON BEHALF OF) HOLDERS OF OUTSTANDING NOTES
IN ANY JURISDICTION IN WHICH THE MAKING OR ACCEPTANCE OF THE EXCHANGE OFFER
WOULD NOT BE IN COMPLIANCE WITH THE LAWS OF SUCH JURISDICTION.
 
   
THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME ON AUGUST 28,
1998, UNLESS EXTENDED. TENDERS OF 10 1/2% SENIOR NOTES DUE 2008 MAY ONLY BE
WITHDRAWN UNDER THE CIRCUMSTANCES DESCRIBED IN THE PROSPECTUS AND THE LETTER OF
TRANSMITTAL.
    
 
                   THE EXCHANGE AGENT FOR THE EXCHANGE OFFER:
 
   
                         HARRIS TRUST AND SAVINGS BANK
    
 
   
<TABLE>
<S>                                                 <C>
         By Registered or Certified Mail:                     By Hand or Overnight Delivery:
           Harris Trust and Savings Bank                       Harris Trust and Savings Bank
             c/o Harris Trust Company                            c/o Harris Trust Company
                    of New York                                         of New York
                   P.O. Box 1010                                      88 Pine Street
                Wall Street Station                                     19th Floor
              New York, NY 10268-1010                               New York, NY 10005
                                    Facsimile, Transmission Number:
                                   (For Eligible Institutions Only)
                                            (212) 701-7636
                                          Confirm Receipt of
                                        Facsimile by Telephone:
                                            (212) 701-7624
</TABLE>
    
 
     DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS, OR
TRANSMISSION VIA FACSIMILE, TELEGRAM OR TELEX, OTHER THAN AS SET FORTH ABOVE,
WILL NOT CONSTITUTE A VALID DELIVERY.
 
     This form is not to be used to guarantee signatures. If a signature on the
Letter of Transmittal is required to be guaranteed by an "Eligible Institution"
under the instructions thereto, such signature guarantee must appear in the
applicable space provided in the signature box on the Letter of Transmittal.
<PAGE>   14
 
Ladies and Gentlemen:
 
     The undersigned hereby tender(s) to the Company, upon the terms and subject
to the conditions set forth in the Prospectus, receipt of which is hereby
acknowledged, the principal amount of Outstanding Notes set forth below,
pursuant to the guaranteed delivery procedures set forth in the Prospectus under
the caption "The Exchange Offer -- Guaranteed Delivery Procedures."
 
     Subject to and effective upon acceptance for exchange of the Outstanding
Notes tendered herewith, the undersigned hereby sells, assigns and transfers to
or upon the order of the Company all right, title and interest in and to, and
any and all claims in respect of or arising or having arisen as a result of the
undersigned's status as a holder of, all Outstanding Notes tendered hereby. In
the event of a termination of the Exchange Offer, the Outstanding Notes tendered
pursuant thereto will be returned promptly to the tendering Outstanding Note
holder.
 
     The undersigned hereby represents and warrants that the undersigned accepts
the terms and conditions of the Prospectus and the Letter of Transmittal, has
full power and authority to tender, sell, assign and transfer the Outstanding
Notes tendered hereby and that the Company will acquire good and unencumbered
title thereto, free and clear of all liens, restrictions, charges and
encumbrances and not subject to any adverse claim. The undersigned will, upon
request, execute and deliver any additional documents deemed by the Exchange
Agent or the Company to be necessary or desirable to complete the sale,
assignment and transfer of the Outstanding Notes tendered.
 
     All authority herein conferred or agreed to be conferred by this Notice of
Guaranteed Delivery shall survive the death or incapacity of the undersigned and
every obligation of the undersigned under this Notice of Guaranteed Delivery
shall be binding upon the heirs, personal representatives, executors,
administrators, successors, assigns, trustees in bankruptcy and other legal
representatives of the undersigned.
<PAGE>   15
 
                            PLEASE SIGN AND COMPLETE
 
<TABLE>
<S>                                         <C>
Signature(s) of Registered Holder(s) or
Authorized Signatory:                       Address(es): -----------------------------
 
------------------------------------------  ------------------------------------------
 
------------------------------------------  ------------------------------------------
 
Name(s) of Registered Holder(s):            Area Code and Telephone No.:
 
------------------------------------------  ------------------------------------------
 
------------------------------------------
 
Principal Amount of Outstanding Notes       If Outstanding Notes will be delivered by
  Tendered:                                 a book-entry transfer, provide the
                                            following information
 
------------------------------------------
 
Certificate No(s) of Outstanding Notes      Transaction Code No.: --------------------
(if available)
 
------------------------------------------  Depository Account No.: ------------------
</TABLE>
 
This Notice of Guaranteed Delivery must be signed by the registered holder(s) of
Outstanding Notes exactly as their name(s) appear(s) on the Outstanding Notes or
by person(s) authorized to become registered holder(s) by endorsements and
documents transmitted with this Notice of Guaranteed Delivery. If signature is
by a trustee, guardian, attorney-in-fact, officer of a corporation, executor,
administrator, agent or other representative, such person must provide the
following information:
 
                      PLEASE PRINT NAME(S) AND ADDRESS(ES)
 
Name(s): ----------------------------------------------------------------------
 
Capacity: ---------------------------------------------------------------------

-------------------------------------------------------------------------------

Address(es): ------------------------------------------------------------------

------------------------------------------------------------------------------- 

                                       15
<PAGE>   16
 
                                   GUARANTEE
                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
     The undersigned, a member of a registered national securities exchange or a
member of the National Association of Securities Dealers, Inc. or a commercial
bank or trust company having an office or correspondent in the United States
(each, an "Eligible Institution"), hereby guarantees that, within three business
days from the date of this Notice of Guaranteed Delivery, a properly completed
and validly executed Letter of Transmittal (or a facsimile thereof), together
with Outstanding Notes tendered hereby in proper form for transfer (or
confirmation of the book-entry transfer of such Outstanding Notes into the
Exchange Agent's account at a Book-Entry Transfer Facility) and all other
required documents will be deposited by the undersigned with the Exchange Agent
at one of its addresses set forth above.
 
<TABLE>
<S>                                                    <C>
Name of Firm: ------------------------------------
                                                       -----------------------------------------------------
                                                                                        Authorized Signature
 
Address: -----------------------------------------      Name: ----------------------------------------------

                                                        Title: ---------------------------------------------

Area Code and Telephone No.: ------------------         Date: ----------------------------------------------
</TABLE>
 
DO NOT SEND OUTSTANDING NOTES WITH THIS FORM. ACTUAL SURRENDER OF OUTSTANDING
NOTES MUST BE MADE PURSUANT TO, AND BE ACCOMPANIED BY, A PROPERLY COMPLETED AND
VALIDLY EXECUTED LETTER OF TRANSMITTAL AND ANY OTHER REQUIRED DOCUMENTS.
 
                                       16
<PAGE>   17
 
                              SCHUFF STEEL COMPANY
 
                               OFFER TO EXCHANGE
                         10 1/2% SENIOR NOTES DUE 2008
                          FOR ANY AND ALL OUTSTANDING
                         10 1/2% SENIOR NOTES DUE 2008
 
   
THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME ON AUGUST 28,
1998, UNLESS EXTENDED. TENDERS OF 10 1/2% SENIOR NOTES DUE 2008 MAY ONLY BE
WITHDRAWN UNDER THE CIRCUMSTANCES DESCRIBED IN THE PROSPECTUS AND THE LETTER OF
TRANSMITTAL.
    
 
                                                                          , 1998
 
To Our Clients:
 
   
     Enclosed for your consideration is the Prospectus dated July 21, 1998 (the
"Prospectus") and the related Letter of Transmittal and instructions thereto
(the "Letter of Transmittal") in connection with the offer (the "Exchange
Offer") of Schuff Steel Company, a Delaware corporation ("the Company"), to
exchange $1,000 principal amount of its 10 1/2% Senior Notes due 2008 (the
"Exchange Notes") for each $1,000 principal amount of its outstanding 10 1/2%
Senior Notes due 2008 (the "Outstanding Notes").
    
 
     Consummation of the Exchange Offer is subject to certain conditions
described in the Prospectus. Capitalized terms used herein but not defined shall
have the meanings ascribed to them in the Prospectus.
 
     WE ARE THE REGISTERED HOLDER OF OUTSTANDING NOTES HELD BY US FOR YOUR
ACCOUNT. A TENDER OF ANY SUCH OUTSTANDING NOTES CAN BE MADE ONLY BY US AS THE
REGISTERED HOLDER AND PURSUANT TO YOUR INSTRUCTIONS. THE LETTER OF TRANSMITTAL
IS FURNISHED TO YOU FOR YOUR INFORMATION ONLY AND CANNOT BE USED BY YOU TO
TENDER OUTSTANDING NOTES HELD BY US FOR YOUR ACCOUNT.
 
     Accordingly, we request instructions as to whether you wish us to tender
any or all such Outstanding Notes held by us for your account pursuant to the
terms and conditions set forth in the Prospectus and the Letter of Transmittal.
We urge you to read carefully the Prospectus and the Letter of Transmittal
before instructing us to tender your Outstanding Notes.
 
   
     Your instructions to us should be forwarded as promptly as possible in
order to permit us to tender Outstanding Notes on your behalf in accordance with
the provisions of the Exchange Offer. THE EXCHANGE OFFER WILL EXPIRE AT 5:00
P.M., NEW YORK CITY TIME ON AUGUST 28, 1998 (THE "EXPIRATION DATE"), UNLESS
EXTENDED. Outstanding Notes tendered pursuant to the Exchange Offer may only be
withdrawn under the circumstances described in the Prospectus and the Letter of
Transmittal.
    
 
     Your attention is directed to the following:
 
          1.  The Exchange Offer is for the entire aggregate principal amount of
     Outstanding Notes.
 
          2.  Consummation of the Exchange Offer is conditioned upon the
     conditions set forth in the Prospectus under the caption "The Exchange
     Offer --Conditions."
 
          3.  Tendering holders may withdraw their tender at any time until the
     Expiration Date.
 
          4.  Any transfer taxes incident to the transfer of Outstanding Notes
     from the tendering holder to the Company will be paid by the Company,
     except as provided in the Prospectus and the instructions to the Letter of
     Transmittal.
 
          5.  The Exchange Offer is not being made to (nor will the surrender of
     Outstanding Notes for exchange be accepted from or on behalf of) holders of
     Outstanding Notes in any jurisdiction in which the making or acceptance of
     the Exchange Offer would not be in compliance with the laws of such
     jurisdiction.
<PAGE>   18
 
          6.  The acceptance for exchange of Outstanding Notes validly tendered
     and not validly withdrawn and the issuance of Exchange Notes will be made
     as promptly as practicable after the Expiration Date. However, subject to
     rules promulgated pursuant to the Securities Exchange Act of 1934, as
     amended (the "Exchange Act"), the Company expressly reserves the right to
     delay acceptance of any of the Outstanding Notes or to terminate the
     Exchange Offer and not accept for purchase any Outstanding Notes not
     theretofore accepted if any of the conditions set forth in the Prospectus
     under the caption "The Exchange Offer -- Conditions" shall not have been
     satisfied or waived by the Company.
 
          7.  The Company expressly reserves the right, in its sole discretion,
     (i) to delay accepting any Outstanding Notes, (ii) to extend the Exchange
     Offer, (iii) to amend the terms of the Exchange Offer or (iv) to terminate
     the Exchange Offer. Any delay, extension, amendment or termination will be
     followed as promptly as practicable by oral or written notice to the
     Exchange Agent and the Company will mail to the registered holders an
     announcement thereof, each prior to 9:00 a.m., New York City time, on the
     next business day after the previously scheduled Expiration Date. Except as
     otherwise provided in the Prospectus, withdrawal rights with respect to
     Outstanding Notes tendered pursuant to the Exchange Offer will not be
     extended or reinstated as a result of an extension or amendment of the
     Exchange Offer.
 
          8.  Consummation of the Exchange Offer may have adverse consequences
     to non-tendering Outstanding Note holders, including that the reduced
     amount of Outstanding Notes as a result of the Exchange Offer may adversely
     affect the trading market, liquidity and market price of the Outstanding
     Notes.
 
     If you wish to have us tender any or all of the Outstanding Notes held by
us for your account, please so instruct us by completing, executing and
returning to us the instruction form that follows.
 
                                       18
<PAGE>   19
 
                              SCHUFF STEEL COMPANY
 
                   INSTRUCTIONS REGARDING THE EXCHANGE OFFER
                              WITH RESPECT TO THE
                         10 1/2% SENIOR NOTES DUE 2008
 
     THE UNDERSIGNED ACKNOWLEDGE(S) RECEIPT OF YOUR LETTER AND THE ENCLOSED
DOCUMENTS REFERRED TO THEREIN RELATING TO THE EXCHANGE OFFER OF THE COMPANY.
 
     THIS WILL INSTRUCT YOU WHETHER TO TENDER THE PRINCIPAL AMOUNT OF
OUTSTANDING NOTES INDICATED BELOW HELD BY YOU FOR THE ACCOUNT OF THE UNDERSIGNED
PURSUANT TO THE TERMS OF AND CONDITIONS SET FORTH IN THE PROSPECTUS AND THE
LETTER OF TRANSMITTAL.
 
Box 1  [  ]  Please tender the Outstanding Notes held by you for my account, as
             indicated below.
 
Box 2  [  ]  Please do not tender any Outstanding Notes held by you for my
             account.
 
Date:                    , 1998
 
Principal Amount of Outstanding Notes to be Tendered:
 
$                                                                              *
------------------------------------------------------
(must be in the principal amount of $1,000 or an integral multiple thereof)
------------------------------------------------------
 
------------------------------------------------------
Signature(s)
 
------------------------------------------------------
 
------------------------------------------------------
                           Please print name(s) here
 
------------------------------------------------------
Please type or print address
 
------------------------------------------------------
Area Code and Telephone Number
 
------------------------------------------------------
Taxpayer Identification or Social Security Number
 
------------------------------------------------------
My Account Number with You
 
---------------
 
* UNLESS OTHERWISE INDICATED, SIGNATURE(S) HEREON BY BENEFICIAL OWNER(S) SHALL
  CONSTITUTE AN INSTRUCTION TO THE NOMINEE TO TENDER ALL OUTSTANDING NOTES OF
  SUCH BENEFICIAL OWNER(S).
 
                                       19
<PAGE>   20
 
   
                         HARRIS TRUST AND SAVINGS BANK
    
   
                      C/O HARRIS TRUST COMPANY OF NEW YORK
    
   
                                 P.O. BOX 1010
    
   
                              WALL STREET STATION
    
   
                            NEW YORK, NY 10268-1010
    
 
                              SCHUFF STEEL COMPANY
 
                               OFFER TO EXCHANGE
 
                         10 1/2% SENIOR NOTES DUE 2008
                          FOR ANY AND ALL OUTSTANDING
                         10 1/2% SENIOR NOTES DUE 2008
 
   
   THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME ON AUGUST
   28, 1998, UNLESS EXTENDED. TENDERS OF 10 1/2% SENIOR NOTES DUE 2008 MAY
   ONLY BE WITHDRAWN UNDER THE CIRCUMSTANCES DESCRIBED IN THE PROSPECTUS AND
   THE LETTER OF TRANSMITTAL.
    
 
To Brokers, Dealers, Commercial Banks, Trust Companies and other Nominees:
 
   
     We have been appointed by Schuff Steel Company, a Delaware corporation (the
"Company"), to act as the Exchange Agent in connection with the offer (the
"Exchange Offer") of the Company to exchange $1,000 principal amount of its
10 1/2% Senior Notes due 2008 (the "Exchange Notes") for each $1,000 principal
amount of its 10 1/2% Senior Notes due 2008 (the "Outstanding Notes"), upon the
terms and subject to the conditions set forth in the Prospectus dated July 21,
1998 (the "Prospectus") and in the related Letter of Transmittal and the
instructions thereto (the "Letter of Transmittal").
    
 
     Enclosed herewith are copies of the following documents:
 
          1. The Prospectus;
 
          2. The Letter of Transmittal for your use and for the information of
     your clients, together with guidelines of the Internal Revenue Service for
     Certification of Taxpayer Identification Number on Substitute Form W-9
     providing information relating to backup federal income tax withholding;
 
          3. Notice of Guaranteed Delivery to be used to accept the Exchange
     Offer if the Notes and all other required documents cannot be delivered to
     the Exchange Agent on or prior to the Expiration Date (as defined);
 
          4. A form of letter which may be sent to your clients for whose
     account you hold the Notes in your name or in the name of a nominee, with
     space provided for obtaining such clients' instructions with regard to the
     Exchange Offer; and
 
          5. A return envelope addressed to the Exchange Agent.
 
   
     PLEASE NOTE THAT THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY
TIME ON AUGUST 28, 1998 (THE "EXPIRATION DATE"), UNLESS EXTENDED. WE URGE YOU TO
CONTACT YOUR CLIENTS AS PROMPTLY AS POSSIBLE.
    
 
     The Company will not pay any fees or commission to any broker or dealer or
other person (other than to the Exchange Agent) for soliciting tenders of the
Notes pursuant to the Exchange Offer. You will be reimbursed for customary
mailing and handling expenses incurred by you in forwarding the enclosed
materials to your clients.
<PAGE>   21
 
     Additional copies of the enclosed materials may be obtained by contacting
the Exchange Agent as provided in the enclosed Letter of Transmittal.
 
                                      Very truly yours,
 
   
                                      Harris Trust and Savings Bank
    
 
NOTHING CONTAINED HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU OR
ANY OTHER PERSON THE AGENT OF THE COMPANY OR THE EXCHANGE AGENT OR AUTHORIZE YOU
OR ANY OTHER PERSON TO GIVE ANY INFORMATION OR MAKE ANY REPRESENTATION ON BEHALF
OF ANY OF THEM WITH RESPECT TO THE EXCHANGE OFFER NOT CONTAINED IN THE
PROSPECTUS OR THE LETTER OF TRANSMITTAL.