The Right and Wrong Way to Pour a Curb

The wrong way and the right way to pour a window curb at floor level. If you see concrete touching the window frame it's wrong. I've shown a lot of variations of this because I see it way too often. In this case I compare to the correct way and a slightly ok way.

The correct way is to establish where the bottom of the window frame will be in relation to finished floor level (yes this affects the top of the window frame so it needs to be custom sized to match doors). A curb of high strength grout should then be poured (not more than 2" to 2-1/2" tall without adding steel) to 1/4" below the level of the window frame.

Also critical is not pouring the curb wider than the window frame or it will keep the flooring from finishing to it. The curb should be coated with a liquid waterproofing before installing.

I do not recommend the third option shown here using a 1x buck at floor level but it is better than backfilling with grout directly against the window frame. If a wood buck is used then the curb needs to be fully waterproofed then the buck needs to be coated fully as well to prevent any moisture.