[LETTERHEAD OF THACHER PROFFITT & WOOD LLP]







                                                   December 31, 2004


Impac Secured Assets Corp.                  Impac Funding Corporation
1401 Dove Street                            1401 Dove Street
Newport Beach, California 92660             Newport Beach, California 92660

Impac Mortgage Holdings, Inc.               Standard & Poor's, A Division of The
1401 Dove Street                            McGraw-Hill Companies, Inc.
Newport Beach, California 92660             55 Water Street, 41st Floor
                                            New York, New York 10041

Wells Fargo Bank, N.A.                      Bear, Stearns & Co. Inc.
9062 Old Annapolis Road                     383 Madison Avenue
Columbia, Maryland 21045                    New York, New York 10179

                  Opinion: Underwriting Agreement
                  Impac Secured Assets Corp.
                  Mortgage Pass-Through Certificates, Series 2004-4
                  -------------------------------------------------

Ladies and Gentlemen:

         We have acted as counsel to Impac Funding Corporation (the "Seller"),
Impac Secured Assets Corp. (the "Depositor") and Impac Mortgage Holdings, Inc.
("IMH") in connection with (i) the Mortgage Loan Purchase Agreement, dated as of
December 31, 2004 (the "Seller Sale Agreement"), among the Seller, the Depositor
and IMH, (ii) the Pooling and Servicing Agreement, dated as of December 31, 2004
(the "Pooling and Servicing Agreement"), among the Seller (in such capacity, the
"Master Servicer"), the Depositor and Wells Fargo Bank, N.A. (the "Trustee"),
and the certificates issued pursuant thereto designated as Mortgage Pass-Through
Certificates, Series 2004-4 (collectively, the "Certificates"), (iii) the
Underwriting Agreement, dated December 29, 2004 (the "Underwriting Agreement"),
among the Seller, the Depositor, IMH and Bear, Stearns & Co. Inc. ("Bear
Stearns"; or the "Underwriter"), (iv) the Prospectus Supplement, dated December
29, 2004 (the "Prospectus Supplement"), and the Prospectus to which it relates,
dated August 30, 2004 (the "Base Prospectus"; together with the Prospectus
Supplement, the "Prospectus") and (v) the Custodial Agreement, dated as of
December 31, 2004 (the "Custodial Agreement"), among the Trustee, the Depositor,
the Seller (in such capacity, the "Master Servicer") and Deutsche Bank National
Trust Company (the "Custodian"). The Seller Sale Agreement, the Pooling and
Servicing Agreement, the Underwriting Agreement and the Custodial Agreement are
collectively referred to herein as the "Agreements." Capitalized terms not
defined herein have the meanings assigned to them in the Agreements.

         In rendering this opinion letter, as to relevant factual matters we
have examined the documents described above and such other documents as we have
deemed necessary including, where we have deemed appropriate, representations or
certifications of officers of parties thereto or public officials. In rendering
this opinion letter, except for the matters that are specifically addressed in
the opinions expressed below, with your permission we have assumed, and are



Opinion:  Underwriting Agreement                                         Page 2.
Impac Secured Assets Corp., Series 2004-4
December 31, 2004

relying thereon without independent investigation, (i) the authenticity of all
documents submitted to us as originals or as copies thereof, and the conformity
to the originals of all documents submitted to us as copies, (ii) the necessary
entity formation and continuing existence in the jurisdiction of formation, and
the necessary licensing and qualification in all jurisdictions, of all parties
to all documents, (iii) the necessary authorization, execution, delivery and
enforceability (as limited by bankruptcy and other insolvency laws) of all
documents, and the necessary entity power and authority with respect thereto,
and (iv) that there is not any other agreement that modifies or supplements the
agreements expressed in any document to which this opinion letter relates and
that renders any of the opinions expressed below inconsistent with such document
as so modified or supplemented. In rendering this opinion letter, except for the
matters that are specifically addressed in the opinions expressed below, we have
made no inquiry, have conducted no investigation and assume no responsibility
with respect to (a) the accuracy of and compliance by the parties thereto with
the representations, warranties and covenants as to factual matters contained in
any document or (b) the conformity of the underlying assets and related
documents to the requirements of any agreement to which this opinion letter
relates.

         In rendering this opinion letter, any opinion expressed herein with
respect to the enforceability of any right or obligation is subject to (i)
general principles of equity, including concepts of materiality, reasonableness,
good faith and fair dealing and the possible unavailability of specific
performance and injunctive relief, regardless of whether considered in a
proceeding in equity or at law, (ii) bankruptcy, insolvency, receivership,
reorganization, liquidation, voidable preference, fraudulent conveyance and
transfer, moratorium and other similar laws affecting the rights of creditors or
secured parties, (iii) the effect of certain laws, regulations and judicial and
other decisions upon (a) the availability and enforceability of certain
remedies, including the remedies of specific performance and self-help, and
provisions purporting to waive the obligation of good faith, materiality, fair
dealing, diligence, reasonableness or objection to judicial jurisdiction, venue
or forum and (b) the enforceability of any provision the violation of which
would not have any material adverse effect on the performance by any party of
its obligations under any agreement and (iv) public policy considerations
underlying United States federal securities laws, to the extent that such public
policy considerations limit the enforceability of any provision of any agreement
which purports or is construed to provide indemnification with respect to
securities law violations. However, the non-enforceability of any provisions
referred to in foregoing clause (iii) will not, taken as a whole, materially
interfere with the practical realization of the benefits of the rights and
remedies included in any such agreement which is the subject of any opinion
expressed below, except for the consequences of any judicial, administrative,
procedural or other delay which may be imposed by, relate to or arise from
applicable laws, equitable principles and interpretations thereof.

         This opinion letter is based upon our review of the documents referred
to herein. We have conducted no independent investigation with respect to the
facts contained in such documents and relied upon in rendering this opinion
letter. We also note that we do not represent any of the parties to the
transactions to which this opinion letter relates or any of their affiliates in
connection with matters other than certain transactions. However, the attorneys
in this firm who are directly involved in the representation of parties to the
transactions to which this opinion letter relates, after such consultation with
such other attorneys in this firm as they deemed



Opinion:  Underwriting Agreement                                         Page 3.
Impac Secured Assets Corp., Series 2004-4
December 31, 2004

appropriate, have no actual present knowledge of the inaccuracy of any fact
relied upon in rendering this opinion letter. In addition, if we indicate herein
that any opinion is based on our knowledge, our opinion is based solely on the
actual present knowledge of such attorneys after such consultation with such
other attorneys in this firm as they deemed appropriate.

         In rendering this opinion letter, we do not express any opinion
concerning any law other than the laws of the State of New York and the federal
laws of the United States, including without limitation the Securities Act of
1933, as amended (the "1933 Act"). We do not express any opinion herein with
respect to any matter not specifically addressed in the opinions expressed
below, including without limitation (i) any statute, regulation or provision of
law of any county, municipality or other political subdivision or any agency or
instrumentality thereof or (ii) the securities or tax laws of any jurisdiction.

         Based upon and subject to the foregoing, it is our opinion that:

         1. Each of the Agreements to which the Seller, the Depositor, the
Master Servicer or IMH is a party (to the extent that the laws of the State of
New York are designated therein as the governing law thereof), assuming the
necessary entity power and authority therefor, authorization, execution and
delivery thereof by the parties thereto (other than any party as of, and to
which we opine to that effect herein) and the enforceability thereof against the
other parties thereto, is a valid and legally binding agreement under the laws
of the State of New York, enforceable thereunder in accordance with its terms
against the Seller, Depositor, Master Servicer or IMH, as the case may be.

         2. The Certificates, assuming the necessary entity power and authority
therefor, the authorization, execution, authentication and delivery thereof and
the payment therefor in accordance with the applicable Agreements, are validly
issued and outstanding and are entitled to the benefits of the Pooling and
Servicing Agreement.

         3. With respect to each of the Seller, the Depositor and IMH, the
performance of its obligations under each of the Agreements to which it is a
party and the consummation of the transactions contemplated thereby do not
require any consent, approval, authorization or order of, filing with or notice
to any United States federal or State of New York court, agency or other
governmental body under any United States federal or State of New York statute
or regulation that is normally applicable to transactions of the type
contemplated by the Agreements, except such as may be required under the
securities laws of any State of the United States or such as have been obtained,
effected or given.

         4. With respect to each of the Seller, the Depositor and IMH, the
performance of its obligations under each of the Agreements to which it is a
party and the consummation of the transactions contemplated thereby will not
result in any breach or violation of any United States federal or State of New
York statute or regulation that is normally applicable to transactions of the
type contemplated by the Agreements.

         5. The Registration Statement has become effective under the 1933 Act.
In that regard, this is to inform you that, to our knowledge, no stop order
suspending the effectiveness of



Opinion:  Underwriting Agreement                                         Page 4.
Impac Secured Assets Corp., Series 2004-4
December 31, 2004

the Registration Statement has been issued and not withdrawn, and no proceedings
for that purpose have been instituted or threatened under Section 8(d) of the
1933 Act.

         6. The Registration Statement as of its effective date, the date of the
Prospectus Supplement and the date hereof, and the Prospectus as of the date of
the Prospectus Supplement and the date hereof, other than any financial and
statistical information and other marketing materials, including without
limitation those generally described as term sheets and computational materials,
as to which we express no opinion herein, complied as to form in all material
respects with the requirements of the 1933 Act and the applicable rules and
regulations thereunder.

         7. To our knowledge, there are no material contracts, indentures or
other documents of a character required to be described or referred to in either
the Registration Statement or the Prospectus or to be filed as exhibits to the
Registration Statement, other than marketing materials generally described as
term sheets and computational materials, as to which we express no opinion
herein, and those described or referred to therein or filed or incorporated by
reference as exhibits thereto.

         8. The statements made in the Base Prospectus under the heading
"Description of the Securities" insofar as such statements purport to summarize
certain provisions thereof, provide a fair summary of such provisions. The
statements made in the Base Prospectus under the headings "Legal Aspects of
Mortgage Loans -- Applicability of Usury Laws" and "--Alternative Mortgage
Instruments" and "ERISA Considerations", to the extent that those statements
constitute matters of United States federal or State of New York law or legal
conclusions with respect thereto, while not purporting to discuss all possible
consequences of investment in the securities to which they relate, are correct
in all material respects with respect to those consequences or matters that are
discussed therein.

         9. The Pooling and Servicing Agreement is not required to be qualified
under the Trust Indenture Act of 1939, as amended. The Trust Fund created by the
Pooling and Servicing Agreement is not an "investment company" within the
meaning of the Investment Company Act of 1940, as amended.

         10. The Class 1-A-1, Class 1-A-2, Class 1-A-3, Class 2-A-1, Class
2-A-2, Class M-1, Class M-2, Class M-3 and Class M-4 Certificates will be
"mortgage related securities" as defined in Section 3(a)(41) of the Securities
Exchange Act of 1934, as amended, so long as each such class is rated in one of
the two highest rating categories by at least one "nationally recognized
statistical rating organization" as that term is used in that Section.

         This opinion letter is rendered for the sole benefit of each addressee
hereof with respect to the matters specifically addressed herein, and no other
person or entity is entitled to rely hereon. Copies of this opinion letter may
not be made available, and this opinion letter may not be quoted or referred to
in any other document made available, to any other person or entity except (i)
to any applicable rating agency, institution providing credit enhancement or
liquidity support or governmental authority, (ii) to any accountant or attorney
for any person or entity entitled hereunder to rely hereon or to whom or which
this opinion letter may be made available as provided herein and (iii) as
otherwise required by law; provided that none of the foregoing is



Opinion:  Underwriting Agreement                                         Page 5.
Impac Secured Assets Corp., Series 2004-4
December 31, 2004

entitled to rely hereon unless an addressee hereof. We assume no obligation to
revise, supplement or withdraw this opinion letter, or otherwise inform any
addressee hereof or other person or entity, with respect to any change occurring
subsequent to the delivery hereof in any applicable fact or law or any judicial
or administrative interpretation thereof, even though such change may affect a
legal analysis or conclusion contained herein. In addition, no attorney-client
relationship exists or has existed by reason of this opinion letter between our
firm and any addressee hereof or other person or entity except for any addressee
that is identified in the first paragraph hereof as a person or entity for which
we have acted as counsel in rendering this opinion letter. In permitting
reliance hereon by any person or entity other than such an addressee for which
we have acted as counsel, we are not acting as counsel for such other person or
entity and have not assumed and are not assuming any responsibility to advise
such other person or entity with respect to the adequacy of this opinion letter
for its purposes.

                                                Very truly yours,

                                                /s/ THACHER PROFFITT & WOOD LLP