Janus International (JBI) 8-K Changes in Registrant's Certifying Accountant

Exhibit 16.1

March 21, 2024

Securities and Exchange Commission

100 F Street N.E.

Washington, D.C. 20549

We have been furnished with a copy of the response to Item 4.01 of Form 8-K for the event that occurred on March 18, 2024, to be filed by our former client, the Janus International Group, Inc. We agree with the statements made in response to that Item insofar as they relate to our Firm.

Very truly yours,

/s/ BDO USA, P.C.

BDO USA, P.C., a Virginia professional corporation, is the U.S. member of BDO International Limited, a UK company limited by guarantee, and forms part of the international BDO network of independent member firms.

BDO is the brand name for the BDO network and for each of the BDO Member Firms.