Does the Drip Cap Go Over the Window Or Trim?

Does the Drip Cap Go Over the Window Or Trim?

Does the Drip Cap Go Over the Window Or Trim?

A drip cap is an L-shaped flashing that is installed after windows and doors are installed (but before the siding is installed) to prevent moisture from seeping in from above. One leg of the “L” is placed over the window or door brick mold, while the other is concealed behind the siding that will be installed above.

The water will drip back out through the top of the siding. As an alternative, the leg that is installed above can be stapled to a ledger board along with a 1/2″ bead, or nail on a matching piece of lumber.

When installing drip caps over existing windows, never extend the drip cap over your new windowsill. This could cause water to collect either outside or in the window sill under your new casement window sills – creating a moist area that attracts wood-rotting mold and mildew.

When the inside window trim is installed, the drip cap should not go over the outside of the new trim. Rather, it should be flush with the mold or siding to which it is attached, with no overlap of any kind. In some cases, if there is existing siding that needs to be replaced along with your windows, you may find that it isn’t possible to install a drip cap at all.

This is because there’s no framing member or piece of wood to which you can attach the drip cap. In this case, you’ll have to make sure that you are installing new wood on top of your windows first (following proper moisture exclusion techniques) and then installing your new siding after that.

Drip caps can look a little odd when installed on exterior windows or doors. You can install a drip cap with molding to conceal the seam, but this will typically be best done when the rest of the trim is installed.

You can also purchase pre-made rewrapped drip caps at some home improvement stores, and they come in various styles that are designed more for use on exterior doors than windows. These typically come in aluminum or zinc-plated plastic, and these won’t need any stapling or sealing.