July 1, 2022

      KNOW ALL BY THESE PRESENTS, that the undersigned hereby makes, constitutes
and appoints Ramey Jackson as the undersigned's true and lawful attorney-in-
fact, with full power and authority as hereinafter described on behalf of and in
the name, place and stead of the undersigned to:

      (i)   execute for and on behalf of the undersigned, in the undersigned's
            capacity as a director, officer or beneficial owner of shares of
            common stock of Janus International Group, Inc., a Delaware
            corporation (the "Company"), any Schedule 13D or Schedule 13G, and
            any amendments, supplements or exhibits thereto (including any joint
            filing agreements) required to be filed by the undersigned under
            Section 13 of the Securities Exchange Act of 1934, as amended (the
            "Exchange Act"), and the rules and regulations promulgated
            thereunder, and any Forms 3, 4 and 5 and any amendments, supplements
            or exhibits thereto required to be filed by the undersigned under
            Section 16(a) of the Exchange Act;

      (ii)  do and perform any and all acts for and on behalf of the undersigned
            which may be necessary or desirable to complete and execute any such
            Schedule 13D, Schedule 13G, Form 3, 4, or 5 and timely file such
            forms with the United States Securities and Exchange Commission and
            any stock exchange on which the common stock of the Company is then
            listed; and

      (iii) 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 such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary or 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'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 attorney-in- fact, in serving in such capacity at the request
of the undersigned, is not assuming, nor is the Company assuming, any of the
undersigned's responsibilities to comply with Section 13 and Section 16 of the
Exchange Act.

      This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file reports or schedules under Section 13
or Section 16 of the Exchange Act 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 attorney-in-fact.

                                 *  *  *  *  *

      IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of the date first written above.

                                By:   /s/ Anselm Wong
                                      Name:   Anselm Wong
                                      Title:  Chief Financial Officer