How to install a window well | Pro Construction Guide
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How to install a window well

Properly installed, window wells are very good ways to prevent water from leaking into a basement from around foundation windows. Here’s how to install a window well.

Window wells also allow the finish grade to be brought to an elevation higher than the window while still allowing light into the area. The key is to make sure the window wells are set at the proper elevation and drain properly.

This installation was done on an existing building that had water seeping through the joint between the basement window and foundation, but the steps apply to new construction, as well.

Set the elevation

The top of the window well should be at least 2 to 3 inches above finished grade if possible. And since the finish grade should not be closer than 8 or 9 inches to a building’s siding that means the top of a window well should be at least 6 inches down from the siding. If you’ll be installing a window well cover, make sure there’s enough room under the bottom of the siding.

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Put the well in place and make sure it’s centered on the window and leveled. If you’re installing a well cover, now is the time to make sure it will fit against the house and under the siding properly.

How to install a window well

The window well used here is made of heavy-gauge galvanized steel and has mounting holes pre-drilled on each side. Place the well in the hole, level it and mark the hole locations on the foundation with a permanent marker or another easily visible marker.

I like to use ⅜ inch x 1-7/8 inch sleeve anchors to attach the wells to the concrete, because it’s easier to unscrew the nuts from the bolts than it is to remove concrete screws if the wells ever become damaged or need to be removed for any reason.

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Apply appropriate adhesive/caulk and tighten the nuts on the sleeve anchors to achieve a good seal and solid attachment. Place crushed stone inside the well to finish grade.

Remove the well and drill the pilot holes ¼-inch deeper than the anchors with a ⅜-inch masonry bit. Remove the nuts from the sleeve anchors and place the anchors in the holes. While it’s not necessary to use an adhesive or caulk on the well flanges where they meet the foundation, I like to as an added measure of seepage protection. If you want, run a thick bead of heavy-duty concrete adhesive or silicone caulk on the back of the well flanges.

I used Sikaflex Concrete Fix on this installation because I also needed to run a bead of rugged caulk around the window to fix the developing cracks that allowed water into the basement in the first place. The Sikaflex product stays flexible and won’t shrink, making it ideal for both applications.

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Apply a quality silicone to the back of the cover flanges and attach with small Tapcon screws. Backfill around the well to finish grade and installation is complete.

Carefully slide the well into place over the sleeve anchors and screw the nuts back on, tightening them with a socket. Backfill inside the well with more pea gravel or crushed stone, bringing the grade inside the well to no higher than 2 inches below the window.

Since this application also required a window well cover, I placed the cover on top of the well and started to drill pilot holes for the Tapcon concrete screws through the cover in a few locations (two on each side, none were necessary on top since the siding overhung the top of the cover by more than an inch).

I then removed the cover and finished drilling the pilot holes to proper depth. I ran another thick bead of clear silicone on the back of the cover flanges, put the cover in place and attached it to the concrete with the Tapcon screws.

What you’ll need

  • galvanized steel window well
  • pea gravel or crushed stone
  • ⅜-inch x 1-7/8-inch sleeve anchors (6 for each well)
  • 3/16-inch x 1¼-inch tapcon concrete anchors (for the optional well cover)
  • appropriate concrete adhesive (optional)
  • silicone caulk (optional)
  • hammer drill
  • ⅜-inch and 5/32-inch masonry bits
  • socket set
  • shovel
  • level
  • window well cover (if desired)
  • personal protection equipment (safety glasses, gloves, hearing protection)

—By Rob Fanjoy


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