BA235:000BA:104073:LOUISVILLE
030900:1
                                JOINDER AGREEMENT

         This Joinder  Agreement  (the "Joinder  Agreement") is made and entered
into as of December 31, 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");

         (5) Commonwealth Aluminum Corporation, a corporation duly organized and
validly  existing under the laws of the State of Delaware  ("CAC";  each of CAC,
CACI,  Lewisport and Alflex is sometimes  hereafter  referred to as a "Borrower"
and collectively as the "Borrowers");

         (6) The Subsidiary of the Parent identified by the caption  "Subsidiary
Guarantor" on the signature pages hereto (the "Subsidiary Guarantor");

         (7) Alflex E1 LLC, a limited  liability company duly formed and validly
existing under the laws of the State of Delaware (the "New Subsidiary Guarantor"
and, together with the Parent, the Subsidiary  Guarantor and the Borrowers,  the
"Obligors");

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

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

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

         (11)     Bank of Montreal ("Montreal");

         (12)     Credit Agricole Indosuez ("Indosuez");

         (13)     Mellon Bank, N.A. ("Mellon Bank");

         (14)     The Industrial Bank of Japan, Limited ("IBJ"); and

         (15) Firstar Bank, NA ("Firstar" and, together with the  Administrative
Agent, PNC, ABN AMRO, Montreal, Indosuez, Mellon Bank, and IBJ, 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, 1998, an Agreement of Resignation,  Appointment and
Acceptance  dated August 18, 1999, and a Joinder  Agreement  dated as of October
29, 1999 (as amended from time to time, the "Credit Agreement").

B. Parent,  each of the  Borrowers,  each of 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, and by a Joinder  Agreement  dated as of October 29, 1999 (as
amended, the "Pledge Agreement").

C. New  Subsidiary  Guarantor  has  ceased to be an  Immaterial  Subsidiary  (as
defined in the Credit  Agreement) and, as required by Section 9.16 of the Credit
Agreement,  Parent  has  expressed  its  willingness  to  cause  New  Subsidiary
Guarantor to:

                  (i) become a Subsidiary Guarantor (as defined in the Credit
                     Agreement) and, thereby, an Obligor, and

                  (ii)  pledge  and  grant  a  security  interest  in and to its
                  Property (as defined in the Credit Agreement)  pursuant to the
                  Security Documents to the Administrative Agent for the benefit
                  of the Lenders.

                  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  Subsidiary  Guarantor  hereby  executes and delivers this
Agreement to the Lenders,  pursuant to which the New Subsidiary  Guarantor joins
as a "Subsidiary  Guarantor" (as defined in the Credit  Agreement),  and becomes
liable as an  Obligor  under,  each of the  documents  to which  the  Subsidiary
Guarantors are parties  (including  without  limitation the Credit Agreement and
the Pledge  Agreement),  jointly and severally  liable with all other Subsidiary
Guarantors under and with respect to such documents.  Each of the other Obligors
consents to the joinder of the New Subsidiary Guarantor.

         2.  Consent of  Lenders.  Each of the  Lenders  hereby  consents to the
addition of the New Subsidiary  Guarantor as, and agrees that the New Subsidiary
Guarantor shall be, a "Subsidiary  Guarantor"  under the Credit  Agreement,  the
Pledge  Agreement  and  each of the  other  documents  to which  the  Subsidiary
Guarantors are parties.

     3.  Affirmation of  Representations  and  Warranties.  Each of the Obligors
(including the New Subsidiary Guarantor) hereby affirms that the representations
and warranties contained in the Credit Agreement and in the Pledge Agreement are
true and accurate as of the  Effective  Date and 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 Obligors (including the New Subsidiary  Guarantor)
of this Joinder  Agreement has been duly authorized by all necessary  action and
will not:

                  (i) violate any  provision  of law or of any of the  Obligors'
                  (including the New  Subsidiary  Guarantor's)  certificates  of
                  incorporation  or  formation,  or bylaws or limited  liability
                  company agreements,

                  (ii) result in the breach of, or  constitute a default  under,
                  any  agreement  or  instrument  to which  any of the  Obligors
                  (including  the New  Subsidiary  Guarantor)  is a party  or by
                  which  any of  the  Obligors  (including  the  New  Subsidiary
                  Guarantor) or any of their respective property may be bound or
                  affected, or

                  (iii)  result  in  the   creation  of  any  lien,   charge  or
                  encumbrance upon any property or assets of any of the Obligors
                  (including the New Subsidiary  Guarantor),  except as provided
                  by this Joinder  Agreement (in the case of the New  Subsidiary
                  Guarantor).

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  Guarantor  consents to the
entering  into of this  Joinder  Agreement by each of the  Borrowers,  the other
Guarantors and the New Subsidiary  Guarantor.  Each of the Obligors  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
any  Guarantor's  liability in any respect  under its Guaranty.  Each  Guarantor
further  agrees that its  Guaranty  is, by the  execution  and  delivery of this
Joinder  Agreement,  ratified,  confirmed and  reaffirmed  in its 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.  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  Obligors   (including  the  New  Subsidiary
Guarantor)  and the Lenders in all respects on and as of the  effective  date of
this Joinder  Agreement.  Each of the  Obligors  (including  the New  Subsidiary
Guarantor)  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 Subsidiary Guarantor, a copy of
charter  documents,  limited  liability  company  agreement and resolutions
relating to New  Subsidiary  Guarantor's  execution and delivery of this Joinder
Agreement, all certified as true, correct and complete by the sole member of the
New Subsidiary Guarantor; and
                           (ii) 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)  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.

         7.       Covenants.  Each of the Obligors agrees that, by May 8, 2000,
 they shall cause to be delivered to the  Administrative
                  ---------
Agent:

                           (a)  Chattel  Search  Results.  Such legal  opinions,
                  UCC-11 Reports or reports from  nationally-recognized  chattel
                  search  firms  and  similar  information  reflecting  that the
                  security  interests granted to the  Administrative  Agent, for
                  the benefit of the Lenders,  by the New  Subsidiary  Guarantor
                  are first and prior perfected security interests.

                           (b)      Legal Opinions.  The legal opinions of the
                               law firms of:

                           (i) Messrs. Sullivan & Cromwell, substantially in the
                           form of  Exhibit A attached  hereto and  incorporated
                           herein by this reference, and

                           (ii)  Messrs.  Womble,  Carlisle,  Sandridge  & Rice,
                           substantially  in the  form  of  Exhibit  B  attached
                           hereto and incorporated herein by this reference.

                           (c)  Financing   Statements.   All  UCC-1   financing
                  statements  and  other  documents,   duly  executed,   as  the
                  Administrative Agent determines to be necessary to perfect the
                  security   interests   intended  to  be  granted  by  the  New
                  Subsidiary Guarantor under the Pledge Agreement.

Each of the Obligors agrees that the covenants set forth in this Section 7 shall
constitute  affirmative  covenants,  that the failure to comply  therewith shall
constitute an Event of Default under the Credit Agreement and that except as set
forth above there shall be no grace or cure period. Each of the Obligors further
agrees that the Lenders  shall have the right to pursue the  remedies  available
under and/or pursuant to the Credit Agreement should the Obligors fail to comply
with any of such affirmative covenants.

         8.       General Provisions.

(a) Entire Agreement. This Agreement, the Credit Agreement, the Pledge Agreement
and the other  documents to which the  Obligors  (including  the New  Subsidiary
Guarantor) 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,  including the
New Subsidiary Guarantor,  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,  effective as of the date set out
in the preamble of this Agreement.

                          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:

"New Subsidiary Guarantor" Alflex E1 LLC, by its sole member,
                           Alflex 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:

                           Firstar Bank, NA

                           By:
                           Title:

10121015.1