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Community and Q&A

Masonry block wall: To seal or not to seal?

SOTASOTA | Posted in General Questions on

In preparation to insulating my renovation of a 1970s building’s masonry block wall with 2″ XPS foam board attached directly to the masonry block, should I paint the interior masonry block wall with a sealer like DRYLOK¯ Masonry Waterproofer or KILZ 2¯ LATEX Low VOC?

Right now there is a thin coat of cheap latex paint on the block wall.

Russ 🙂

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  1. ohioandy | | #1

    If cheap latex paint has held up for a while, that's proof that the wall is dry and sound, with no intruding moisture issues. I'd skip the expensive coating. As waterproofers, these products are dubious anyway, since in residential applications no film coating on the INSIDE of a masonry wall can long mitigate a water entry problem, which can only be definitively settled with an EXTERIOR approach.

  2. SOTASOTA | | #2

    Thanks Andy. Makes good sense! :-)

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