Gaps between slab and bottom sills
I am remodeling a wood frame house with a concrete slab foundation.
When I removed the carpet in one of the rooms to install ceramic tile, I found that there are relatively large gaps between bottom sills (treated 2x4s) and the concrete slab, because the slab is not completely flat.
My question what is the best way to fill the gaps between the concrete and 2x4s?
So far I have the following ideas, please give me you suggestions:
1) push some tile mortar under the 2x4s as I install tiles
2) polyurethane foam (such as"Good stuff" brand)
3) butyl caulk, that is used for gutter seals