Exhibit 24

                               POWER OF ATTORNEY

Know all by these present, that the undersigned hereby constitutes and appoints
each of James E. Thompson and Kevin R. Holland, signing singly, the
undersigned's true and lawful attorney-in-fact to:

     (1)  execute for and on behalf of the undersigned, in the undersigned's
          capacity as a director, officer and/or employee of GCP Applied
          Technologies Inc. (the "Company"), Forms 3, 4, 5, Form 144 and/or Form
          ID in accordance with Section 16(a) of the Securities Exchange Act of
          1934 and the rules thereunder and/or Rule 144 of the Securities Act of
          1933, respectively;

     (2)  do and perform any and all acts for and on behalf of the undersigned
          which may be necessary or desirable to complete the execution of any
          such Forms 3, 4, 5, Form 144 and Form ID and timely file such form or
          forms with the United States Securities and Exchange Commission; and

     (3)  take any other action of any type whatsoever in connection with the
          foregoing which, in the opinion of such attorney-in-fact, may be of
          benefit to, in the best interest of, or legally required by, the
          undersigned, it being understood that the documents executed by such
          attorney-in-fact on behalf of the undersigned pursuant to this Power
          of Attorney shall be in such form and shall contain such terms and
          conditions as such attorney-in-fact may approve in such attorney-in-
          fact's discretion.

The undersigned hereby grants to each attorney-in-fact full power and authority
to do and perform all and every act and thing whatsoever requisite, necessary
and proper to be done in the exercise of any of the rights and powers herein
granted, as fully to all intents and purposes as the undersigned might or could
do if personally present, with full power of substitution or revocation, hereby
ratifying and confirming all that such attorney-in-fact, or such attorney-in-
fact's substitute or substitutes, shall lawfully do or cause to be done by
virtue of this power of attorney and the rights and powers herein granted. The
undersigned acknowledges that the foregoing attorneys-in-fact, in serving in
such capacity at the request of the undersigned, are not assuming, nor is the
Company assuming, any of the undersigned's responsibilities to comply with
Section 16 of the Securities Exchange Act of 1934 or Rule 144 of the Securities
Act of 1933.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, 5, and Form 144 with
respect to the undersigned's holdings of and transactions in securities issued
by the Company, unless earlier revoked by the undersigned in a signed writing
delivered to the foregoing attorneys-in-fact. This Power of Attorney shall
supersede any and all existing Powers of Attorney with respect to the subject
matter hereof.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed this 17th day of October, 2019.

/s/ Craig A. Merrill
--------------------

Craig A. Merrill