What caulk do I need?

Pick where it goes and whether you’ll paint it. The finder shows the caulks and sealants their makers list for that place, with each one’s water and paint times.

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Four questions before you buy

DAP’s own guide asks four things: is the area exposed to water or humidity, does the joint move with temperature or the structure, will it be painted, and is it indoors or outdoors? The place covers water and indoors or outdoors, and the finder asks about paint. Movement is the ± figure on each product.

What the movement rating means

Sealants tested to ASTM C920 carry a class for the joint movement they’re rated for: GE lists its Supreme Silicone at ±50%, and DAP describes Class 25 as over 50% total movement. Many plain latex caulks are tested to ASTM C834 instead, among them DAP ALEX PLUS and GE Painter’s Pro, which GE rates at under 7% movement.

The toilet base

GE’s guide runs the bead along the front and sides where the base meets the floor, and not between the tank and the bowl. Its 2026 guide adds that some professionals leave a small gap at the back, so a hidden leak shows instead of staying trapped. The code text we read asks for the joint to be sealed but names no caulk, so local code decides the details.

Going over old caulk

DAP, GE, Red Devil and Sashco all say to take the old caulk out first. DAP says AMP shouldn’t go over old sealant, and GE says new silicone over old rarely holds. Getting old silicone off has the steps.

Ventilate while it cures. DAP’s, GE’s and Red Devil’s sheets call for good ventilation, and some sealants give off methanol or acetic acid as they cure.