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                                                                     Exhibit 5.1
                                                   June 26, 1998


Schuff Steel Company
420 South 19th Avenue
Phoenix, Arizona 85069

B & K Steel Fabrications, Inc.
420 South 19th Avenue
Phoenix, Arizona 85069

Addison Structural Services, Inc.
1920 Lado Road
Albany, Georgia 31706

Addison Steel, Inc.
7351 Overland Road
Lockhart, Florida 32810

Quincy Joist Company
520 South Virginia Street
Quincy, Florida 32353-0520

Ladies and Gentlemen:

         Reference is made to the Registration Statement on Form S-4, including
amendments and exhibits thereto (the "Registration Statement"), for the proposed
offer to exchange (the "Exchange Offer") by Schuff Steel Company (the "Company")
and B & K Steel Fabrications, Inc., Addison Structural Services, Inc., Addison
Steel, Inc., and Quincy Joist Company (collectively, the "Guarantors"), of up to
an aggregate of $100 million in principal amount of its 10 1/2% Senior Notes due
2008 ("Exchange Notes") for an equal principal amount of its outstanding 10 1/2%
Senior Notes due 2008 ("Outstanding Notes") and the guarantees by the Guarantors
of the Exchange Notes. The Outstanding Notes were issued, and the Exchange Notes
are issuable, pursuant to an Indenture, dated June 4, 1998, by and among the
Company, the Guarantors and Harris Trust Company of California, as Trustee (the
"Indenture").

         Based on the foregoing, we are of the opinion that:

                  1. The Exchange Notes, when executed by the Company and
authenticated by the Trustee in accordance with the provisions of the Indenture,
and when issued in exchange for Outstanding Notes as contemplated in the
Registration Statement, will constitute valid and binding obligations of the
Company and will be entitled to the benefits of the Indenture.




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June 26, 1998
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                  2. The guarantees by the Guarantors of the Exchange Notes,
when executed by the Guarantors in accordance with the provisions of the
Indenture and when issued as contemplated in the Registration Statement, will
constitute valid and binding obligations of the Guarantors, respectively, and
will be entitled to the benefits of the Indenture.

         In rendering this opinion, we have reviewed and relied upon the
Indenture, the Outstanding Notes, the form of Exchange Notes and such documents,
records, and other instruments of the Company and the Guarantors as we have
deemed necessary and have assumed the following:

                  (i) the opinions expressed herein are subject to and may be
limited by (a) applicable bankruptcy, insolvency, liquidation, fraudulent
transfer, moratorium, reorganization, or other similar laws affecting creditors'
rights generally; (b) rights of acceleration and general equitable principles
and rules of law governing specific performance, estoppel, waiver, injunctive
relief, and other equitable remedies (regardless of whether enforcement is
sought in a proceeding at law or in equity), and the discretion of any court
before which a proceeding may be brought; (c) duties and standards of good
faith, reasonableness and fair dealing imposed on creditors and parties to
contracts; (d) the limitation in certain circumstances of provisions imposing
penalties, forfeitures, late payment charges or an increase in interest rate
upon delinquency in payment or the occurrence of a default; and (e) a court
determination that any fees payable pursuant to a provision requiring the
payment of attorneys' fees is reasonable;

                  (ii) the genuineness of the signatures and the authenticity of
documents submitted to us as originals, and the conformity to originals of all
documents submitted to us as certified or photostatic copies;

                  (iii) the accuracy, completeness, and genuineness of all
representations and certifications, with respect to factual matters, made to or
obtained by us, by officers of the Company, the Guarantors and public officials;
and

                  (iv) the accuracy and completeness of records of the Company
and the Guarantors.

                  The opinions expressed herein are limited solely to the laws
of the State of Arizona, the General Corporation Law of the State of Delaware
and the laws of the United States of America. We express no opinion on the law
of any other jurisdiction or principles of conflicts of law and can assume no
responsibility for the applicability or effect of any such laws or principles.


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June 26, 1998
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                  The opinions expressed herein are limited to the matters
stated herein and no opinion is implied or may be inferred beyond the matters
expressly stated. Without limiting the foregoing, the opinions expressed in this
letter are based upon the law and facts as we understand them in effect on the
date hereof, and we assume no obligation to revise or supplement this opinion
should such law be changed by legislative action, judicial decision, or
otherwise, or should any facts or other matters upon which we have relied be
changed.

         We hereby consent to the filing or the opinion as an exhibit to the
Registration Statement and to the use of our name in the Registration Statement.

                                                     Very truly yours,

                                                     /s/ Snell & Wilmer L.L.P.