Is slab edge caulking necessary?
GBA Editor
| Posted in Energy Efficiency and Durability on
SLAB HAS 2″ RIGID FOAM AND VAPOR BARRIER, WE HAVE INSTALLED RADIANT FLOOR HEAT AND AFTER A YEAR, THE EDGE OF THE SLAB HAS A 1/8 GAP ALL AROUND THE FOUNDATION EDGE. SHOULD WE FILL THIS WITH A HIGH QUALITY SILICONE OR LEAVE IT ALONE. WE WILL BE INSTALLING FLOORING SOON AND WOULD LIKE TO KNOW IF THIS WOULD BE A BENEFIT.
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I would absolutely fill this but it's unclear from your post if the slab is shrinking away from the exterior rigid foam of if it is a gap under the wall. I'm assuming the wall is covering the foam to concrete gap and the crack you are talking about is associated with the sill plate under the wall. If it's the wall plate you don't need to use silicone. An inexpensive white painters caulk or duct sealer in a caulking gun tube would be a better choice.
More details would be helpful
Michael
It sounds like your heated slab was poured tight to your concrete foundation walls. Most heat loss from a slab (particularly a heated one) is at the edges. There should have been 2" foam thermal break at the slab perimeter.
But if, in fact, the slab has shrunk away from the foundation walls, the crack should be filled with urethane caulk (some are specifically made for concrete).