How to Install Basement Window Well Covers? | Fit and Secure

Installing a basement window well cover requires measuring the well, drilling mounting holes, and securing clips or pins to hold the cover in place.

For the full breakdown, see our best Basement Window Well Cover guide.

Getting the install right starts with three numbers—width at the widest point, projection from the house wall to the outer edge, and height from ground to the well’s top edge—then matching the mounting method to the cover material. Plastic and aluminum covers follow different steps, but the prep work and safety rules stay the same.

What Three Measurements Do You Need First?

Measure the well’s width at its widest point. Then measure the projection—how far the well extends from the foundation wall to its outer edge. Finally, measure the height from ground level to the well’s top edge. Write all three down before shopping or starting the job.

Clear leaves, dirt, and any standing water from the well. Check the well frame for rust, bends, or loose fasteners—if it is unstable, fix that before mounting a cover. Dry-fit the cover by setting it in place to confirm the size works before you pick up a drill.

If you need help choosing the right cover first, check our roundup of the best basement window well covers for tested options across different sizes and budgets.

Installing A Window Well Cover: Plastic Vs. Aluminum

The two most common cover materials install differently. Identify yours before starting. Plastic covers use spring clips that snap onto the well rim; aluminum covers use rear support brackets and locking pins. The steps below follow a standard installation sequence. For concrete foundations, use a masonry bit and blue concrete screws. For wood siding, switch to self-tapping screws.

Plastic cover steps: Center the cover against the house. Mark mounting points roughly 4–6 inches from the house edge on each side. Place a 2×4 scrap under the marked area to support the plastic while drilling. Drill a 3/16-inch hole through the cover and well rim. Fasten the spring clips so the prongs grab the well edges, but do not tighten fully—leave about a quarter-inch gap between the clip and the well rim. Test-fit the cover, then snap it onto the well rim. The cover should sit flush with no rocking.

Aluminum cover steps: Lay the cover over the well and center it against the house. Locate the rear support brackets and position them against the foundation. Mark the bracket height, then drill 5/32-inch holes. Install the rear brackets with blue concrete screws. Install the pin brackets on the sides, then drill 1/4-inch holes for the locking pins. If the cover overhangs, trim it with a jigsaw fitted with a fine-tooth blade. Insert locking pins from the inside. Lowe’s window well cover installation guide walks through the same sequence with diagrams for each step.

Three Mistakes That Ruin A Good Install

Old or dull drill bits crack plastic—use a sharp bit every time. Drilling without a wood scrap underneath deforms the plastic around the hole. Over-tightening spring clips warps the cover and creates an uneven seal, so stop at that quarter-inch gap.

Other common issues include skipping the dry-fit, measuring at only one point instead of the widest part, and failing to test drainage after installation.

Final Fit Checks And Egress Requirements

The cover must sit snug with no rattling and no visible gaps between the cover edge and the well rim. Remove all protective film before snapping the cover fully down—film left in place traps moisture and looks unfinished.

Test drainage by pouring a small amount of water around the cover. Water should run away from the house, not pool inside the well. Confirm the cover can be opened from inside without tools if the window serves as an egress route.