AskCodeMan

Do door and window sill required to have the proper slope away from the exterior for proper drainage?

Hi Richard,

You are, of course, referring to the exterior side.

The door sill would be the door threshold which is sloped to drain to the exterior. If the threshold did not cover all of the exposed edge of the slab, then there may have been an installation problem. Depending on the construction (CMU or frame) would depend on what would need to be done to correct it.

The best result for the above where the slab edge projects beyond the threshold is, of course, to slope it from the edge of the threshold down and out, however, there may be conditions which need to be taken into consideration for each specific installation. However, generally speaking, yes, you want the threshold and the exposed slab projecting beyond the threshold to be sloping down and outward.

For windows installed in frame construction, the sill is part of the window. If there has been a trim added below the window, yes, slope the top of the trim, and, if the trim is wood, the top of the projecting wood trim needs to be protected and covered with a flashing.

For windows installed in masonry openings, the sill is also part of the window, but what you are referring to (I suspect) is the stucco which has been applied to fill the exposed top of the wall which extends out past the window sill. That stucco needs to be tightly adhered, if it sounds hollow as many do, or have hollow areas as many others have, those hollow (loose) areas need to be removed, cleaned, have a bonding agent applied, then re-stuccoed. And, yes, the stucco needs to be sloped down and outward.