NB005:0NB15:70784:LOUISVILLE
090899:1
                                JOINDER AGREEMENT

         This Joinder  Agreement  (the "Joinder  Agreement") is made and entered
into as of October 29, 1999, by and among:

         (1)  Commonwealth  Industries,  Inc., a corporation  duly organized and
validly  existing under the laws of the State of Delaware (the "Parent") and the
successor by merger to CI Holdings, Inc.;

         (2) Commonwealth Aluminum Lewisport, Inc., a corporation duly organized
and validly  existing under the laws of the State of Delaware and formerly known
as Commonwealth Aluminum Corporation ("Lewisport");

         (3) Alflex  Corporation,  a  corporation  duly  organized  and  validly
existing under the laws of the State of Delaware ("Alflex");

         (4) Commonwealth  Aluminum Concast,  Inc., a corporation duly organized
and validly existing under the laws of the State of Ohio ("CACI";  each of CACI,
Lewisport  and Alflex is sometimes  hereafter  referred to as a  "Borrower"  and
collectively as the "Borrowers");

         (5) Commonwealth Aluminum Corporation, a corporation duly organized and
validly existing under the laws of the State of Delaware (the "New Borrower");

         (6) The Subsidiary of the Parent identified by the caption  "Subsidiary
Guarantor"  on the  signature  pages  hereto (the  "Subsidiary  Guarantor"  and,
together with the Parent and the Borrowers, the "Obligors");

         (7) Bank One, Indiana,  NA, for itself and as administrative  agent for
the Lenders (as hereafter defined) (the "Administrative Agent");

         (8)      PNC Bank, National Association ("PNC");

         (9)      ABN AMRO Bank N.V. ("ABN AMRO");

         (10)     Bank of Montreal ("Montreal");

         (11)     Credit Agricole Indosuez ("Indosuez");

         (12)     Mellon Bank, N.A. ("Mellon Bank"); and

         (13) The Industrial  Bank of Japan,  Limited ("IBJ" and,  together with
the Administrative Agent, PNC, ABN AMRO, Montreal, Indosuez and Mellon Bank, the
"Lenders").




                             PRELIMINARY STATEMENTS:

A. Parent, each of the Borrowers,  each of the Subsidiary Guarantors and each of
the  Lenders  are  parties  to a certain  Second  Amended  and  Restated  Credit
Agreement dated as of December 19, 1997, as amended by Amendment No. 1 to Credit
Agreement dated December 22, 1997, and an Agreement of Resignation,  Appointment
and Acceptance  dated August 18, 1999 (as amended from time to time, the "Credit
Agreement").

B.  Parent,   Lewisport,   Alflex,  CACI,  the  Subsidiary  Guarantors  and  the
Administrative  Agent (as successor to National Westminster Bank PLC pursuant to
the Agreement of Resignation,  Appointment and Acceptance dated August 18, 1999)
are parties to a certain  Amended and  Restated  Pledge and  Security  Agreement
dated as of  November  29,  1996,  as  amended  by  Amendment  No. 1 dated as of
December 19, 1997 (as amended, the "Pledge Agreement").

C.  Lewisport has changed its name,  and the Borrowers  have  requested that the
Lenders consent to such change of name.

D. C.I. Holdings,  Inc., has merged with and into Parent, and the Borrowers have
requested that the Lenders consent to such merger.

E. New Borrower has become affiliated with the Borrowers, and the Borrowers have
requested  that the  Lenders  agree to allow New  Borrower to join as a Borrower
under the Credit Agreement.

                  NOW THEREFORE,  the parties hereto,  in consideration of their
mutual  covenants  and  agreements  hereinafter  set forth and  intending  to be
legally bound hereby, covenant and agree as follows:


1. Joinder.  The New Borrower hereby executes and delivers this Agreement to the
Lenders, pursuant to which the New Borrower joins as a "Borrower" (as defined in
the Credit  Agreement),  and  becomes  liable as a Borrower  under,  each of the
documents to which the Borrowers are parties  (including  without limitation the
Credit  Agreement,  each of the Revolving  Credit  Notes,  each of the Swingline
Notes and the Pledge  Agreement),  jointly and  severally  liable with all other
Borrowers under and with respect to such documents.  Each of the other Borrowers
consents to the joinder of the New Borrower.

         2. Consent of Lenders.  Each of the Lenders  hereby (i) consents to the
change  of  Lewisport's   name  from   Commonwealth   Aluminum   Corporation  to
Commonwealth  Aluminum  Lewisport,  Inc.,  (ii)  consents  to the  merger  of CI
Holdings,  Inc., with and into Parent, and (iii) consents to the addition of the
New Borrower as, and agrees that the New Borrower  shall be, a "Borrower"  under
the Credit  Agreement,  the Revolving  Credit Notes,  the Swingline  Notes,  the
Pledge  Agreement  and each of the other  documents to which the  Borrowers  are
parties.

         3. Affirmation of Representations and Warranties. Each of the Borrowers
(including  the New  Borrower)  hereby  affirms  that  the  representations  and
warranties  contained in the Credit  Agreement  and in the Pledge  Agreement are
true and accurate as of the date of the  execution  and delivery of this Joinder
Agreement. Each further represents and warrants that each has the power to enter
into and perform  this  Joinder  Agreement.  The making and  performance  by the
Borrowers (including the New Borrower) and each of the Subsidiary  Guarantors of
this Joinder  Agreement  has been duly  authorized  by all  necessary  corporate
action and will not violate  any  provision  of law or of any of the  Borrowers'
(including the New  Borrower's)  certificates  of  incorporation  or bylaws,  or
result in the  breach  of, or  constitute  a default  under,  any  agreement  or
instrument  to which any of the  Borrowers  (including  the New Borrower) or any
Subsidiary  Guarantor is a party or by which any of the Borrowers (including the
New Borrower) or any Subsidiary  Guarantor or any of their  respective  property
may be bound or  affected,  or result  in the  creation  of any lien,  charge or
encumbrance  upon any property or assets of any of the Borrowers  (including the
New Borrower) or any  Subsidiary  Guarantor,  except as provided by this Joinder
Agreement   (in  the  case  of  the  New   Borrower).   No  consent,   approval,
authorization,  declaration,  exemption  or other  action  by, or notice to, any
court  or  governmental  or  administrative  agency  or  tribunal  is or will be
required in connection with the execution,  delivery,  performance,  validity or
enforcement  of this Joinder  Agreement or any other  agreement,  instrument  or
document to be executed and delivered pursuant hereto.

         4. No Impairment and Ratification.  Each Subsidiary  Guarantor consents
to the  entering  into  of this  Joinder  Agreement  by  each  of the  Borrowers
(including the New Borrower),  each of the Subsidiary Guarantors and the Lenders
and agrees that neither this Joinder Agreement nor anything  contained herein or
in any other  document or  instrument  delivered in  connection  herewith  shall
diminish  or impair its  liability  in any  respect  under its  Guaranty,  which
Guaranty is, by the execution and delivery of this Joinder Agreement,  ratified,
confirmed and reaffirmed in their entirety, and acknowledged to continue in full
force and effect.

         5. Ratification. Except as expressly amended by this Joinder Agreement,
the Credit  Agreement,  the Pledge Agreement and the Guaranties are and shall be
unchanged, and all of the terms, provisions, covenants, agreements,  conditions,
schedules  and  exhibits  thereof or thereto  shall  remain and continue in full
force and effect and are hereby incorporated by reference,  and hereby ratified,
reaffirmed and confirmed by the Borrowers  (including  the New  Borrower),  each
Subsidiary  Guarantor and the Lenders in all respects on and as of the effective
date of this  Amendment.  Each  Subsidiary  Guarantor  and each of the Borrowers
(including the New Borrower)  acknowledges  and agrees that all liens,  security
interests,  and  pledges  heretofore  given  to  the  Lenders  to  secure  their
respective indebtedness to the Lenders shall also secure all obligations arising
hereunder.

         6.  Conditions.  The Lenders'  agreements  and consents in this Joinder
Agreement  are and shall be subject to the prior  satisfaction  of the following
conditions precedent:

                  (a) Execution and Delivery of this Joinder  Agreement.  All of
the  parties to this  Joinder  Agreement  shall have  executed  and  delivered a
counterpart hereof.

                  (b) Evidence of Existence and Authorzation. The Administrative
Agent shall have received the following:

     (i)  for  the  New  Borrower,  a copy of  charter  documents,  by-laws  and
resolutions  relating to New  Borrower's  execution and delivery of this Joinder
Agreement,  all  certified as true,  correct and complete by the Secretary or an
Assistant Secretary of the New Borrower;

     (ii) for Parent, a copy of the charter  documents  reflecting the merger of
CI Holdings,  Inc., with and into the Parent, all certified as true, correct and
complete by the Secretary or an Assistant Secretary of the Parent; and

                           (iii)  for  all  Obligors,   copies  of   resolutions
relating to the execution and delivery of this Joinder
Agreement,  all  certified as true,  correct and complete by the Secretary or an
Assistant Secretary of each Obligor.

                  (c) Chattel Search  Results.  The  Administrative  Agent shall
have   received    legal    opinions,    UCC-11    Reports   or   reports   from
nationally-recognized  chattel search firms and similar  information  reflecting
that the  security  interests  granted to the Lenders by the New Borrower and by
Lewisport are first and prior perfected security interests.

                  (d)  Legal  Opinion.   The  Administrative  Agent  shall  have
received  the legal  opinion  of the law firm of Messrs.  Sullivan  &  Cromwell,
substantially in the form of Exhibit A attached hereto and  incorporated  herein
by this reference.

                  (e)  Proceedings   Satisfactory.   All  proceedings  taken  in
connection with the  transactions  contemplated  herein shall be satisfactory to
the Lenders and their counsel. The Lenders and their counsel shall have received
copies of such  documents as they may request in  connection  therewith,  all in
form and substance satisfactory to the Lenders and their counsel.

                  (f) Financing Statements. The New Borrower shall have executed
and  delivered  to the  Administrative  Agent  for  filing  in  the  appropriate
governmental  offices all UCC-1 financing  statements and other documents as the
Administrative  Agent  determines  to  be  necessary  to  perfect  the  security
interests intended to be granted by the New Borrower under the Pledge Agreement.

         7.       General Provisions.

(a) Entire Agreement. This Agreement, the Credit Agreement, the Pledge Agreement
and the other documents to which the Borrowers  (including the New Borrower) are
parties pursuant to the Credit Agreement  constitute the entire agreement of the
parties  with  respect to the  subject  matter  hereof and  thereof.  No change,
modification,  addition or termination  of this  Agreement  shall be enforceable
unless in writing and signed by the party against whom enforcement is sought.

(b) Definitions.  Terms used and not otherwise defined in this Joinder Agreement
shall have the meanings given to them in the Credit  Agreement,  as amended from
time to time.

(c) Benefit. This Agreement shall be binding upon the Obligors, the New Borrower
and their  respective  successors  and assigns and shall inure to the benefit of
the Lenders and their respective successors and assigns.

(d) Waiver.  No waiver of the  provisions  hereof shall be  effective  unless in
writing and signed by the party to be charged with such waiver.  No waiver shall
be deemed a  continuing  waiver or a waiver in respect of any breach or default,
whether  of a similar  or a  different  nature,  unless  expressly  so stated in
writing.

(e) Governing Law. The validity, construction, interpretation and enforcement of
this  Agreement  shall be construed in accordance  with the laws of the State of
New York without regard to its conflict of laws.

(f) Severability. If any provision of this Agreement or its application shall be
deemed  invalid,   illegal  or  unenforceable  in  any  respect,  the  validity,
construction,  interpretation  and  enforceability of all other  applications of
that provision and of all other provisions and applications  hereof shall not in
any way be affected or impaired.

(g) Further Assurances. From time to time at another party's request and without
further  consideration,  the parties  shall  execute and  deliver  such  further
instruments  and documents,  and take such other action as the requesting  party
may reasonably  request,  in order to complete more effectively the transactions
contemplated in this Agreement.

                  (h) Counterparts. This Agreement may be executed in any number
of  counterparts,  each of which shall be deemed an  original,  but all of which
together  shall  constitute  one and the same  agreement.  This Agreement may be
executed by each party on separate copies,  which copies, when combined so as to
include the signatures of all parties,  shall constitute a single counterpart of
this Agreement.

         IN WITNESS  WHEREOF,  the parties hereto,  by their officers  thereunto
duly  authorized,  have  executed  this  Agreement as of the date set out in the
preamble of this Agreement but actually on the dates set forth below.

                          Commonwealth Industries, Inc.

                                    By:
                                    Title:


                                    Commonwealth Aluminum Lewisport, Inc.

                                    By:
                                    Title:

                                    Alflex Corporation

                                    By:
                                    Title:




                                    Commonwealth Aluminum Concast, Inc.

                                    By:
                                    Title:


                                    Commonwealth Aluminum Corporation

                                    By:
                                    Title:

"Subsidiary Guarantor"              Commonwealth Aluminum Sales Corporation

                                    By:
                                    Title:

                                    Bank One, Indiana, NA

                                    By:
                                    Title:

                                    PNC Bank, National Association

                                    By:
                                    Title:

                                    ABN AMRO Bank N.V.

                                    By:
                                    Title:

                                    Bank of Montreal

                                    By:
                                    Title:

                                    Credit Agricole Indosuez

                                    By:
                                    Title:

                                    Mellon Bank, N.A.

                                    By:
                                    Title:


                                    The Industrial Bank of Japan, Limited

                                    By:
                                    Title: