How to Install a Window Well

Digging the Well and Drain Holes

Measure the size of your window so you know how large of a well you need. Measure the height and width of your window with a tape measure so you know the dimensions. Add 8 inches (20 cm) to the height and 6 inches (15 cm) to the width measurement you took so the well can fit around the outside of the window. For example if you have a window that's 12 inches (30 cm) wide by 30 inches (76 cm) tall, then you need a well that's at least 38 inches (97 cm) tall and 18 inches (46 cm) wide.

Find a prefabricated well that fits your window. Window wells come in various styles so choose one that matches the rest of your home. Pick either a plastic or steel window well for the most durable materials. If you have wells on other ground-level windows, get a matching well for the new one that you're installing. You can buy window wells from your local hardware or home improvement store.

Dig a hole that's slightly wider and deeper than the well. Start your hole next to your home's foundation about 6 inches (15 cm) from the side of your window. Shovel the dirt into a wheelbarrow or tarp so it's easy to transport away from the hole. Continue digging around the window until the hole is about 4–5 inches (10–13 cm) deeper than the bottom of the window sill and 6 inches (15 cm) wider than the well. Contact your utility companies before you start digging to check for any power, gas, or water lines where you plan on putting the window well.

Use an auger to bore through the ground to the gravel under your foundation. Augers are large drills that help dig straight holes in the ground. Position the end of the auger in the center of the hole you just dug to place your drain. Turn the auger on and push it slowly into the ground so it bores down about 1 foot (30 cm). Pull the auger out from the ground to clean off any dirt on the blades. Continue digging out 1 foot (30 cm) at a time until you reach a layer of gravel under your home. If you don't have an auger, then you can use a shovel but it may be more difficult to break through the ground.Tip: Check if your local hardware store offers equipment rentals so you don't have to buy an auger.

Put a perforated tube with a drain cap in the hole so the well can drain. Look for a perforated tube with a 4–5 in (10–13 cm) diameter at your local hardware store. Measure the depth of the drain hole and get a tube that's the same length. Place the tube in the center of the drain hole and drain cap on top so dirt and gravel can't get inside and clog it. You can buy drain caps from your local hardware store. If you can't find a pipe with perforation, then cut 2 in (5.1 cm) long slits on each side every 1 ft (30 cm) along the pipe's length. The drain tube will help divert water out of the well toward your home's weeping tile, which is the underground drainage pipe that moves water away from your home.

Backfill the hole around the tube with gravel. Make sure the tube is centered in the drain hole and hold it in place. Pour gravel around the outside of the tube to provide better drainage for the well and to hold the tube in place. Continue packing gravel into the hole until it's level with the drain cap. You can purchase bags of gravel from home improvement or landscaping stores.

Mounting the Window Well

Set the window well against your foundation so it's level. Put the window well in the hole you dug and push it firmly against the walls of your foundation. Make sure that the edges of the sides of the well are about 3 inches (7.6 cm) from either side of the window, and check that the top of the well extends 2–3 inches (5.1–7.6 cm) above the dirt. Set a level on top of the well to see if it's straight, and pack dirt underneath the lower side if you need to. Ask someone to help you lift and set the well in place if it's too heavy to safely lift on your own. If the window well is closer than 6 inches (15 cm) to your siding, dig your hole deeper until you have a 6 in (15 cm) buffer.

Mark the location of the predrilled holes on your foundation with a marker. Hold the window well tightly against your home and use a marker to put dots on your foundation in the center of each hole. Check that the window well doesn't shift around while you're making your marks or else the holes won't line up when you try to attach the well later on. After you draw all of the marks, take the window well out of the hole. If your window well doesn't already have holes drilled in the sides, then you may need to make your own holes. Use a ⁄8 in (0.95 cm) drill bit meant for metal or plastic depending on what your well is made from, and space your holes about 5 inches (13 cm) apart down each side.

Drill 2 in (5.1 cm) pilot holes in the foundation with a masonry bit. Use a ⁄8 in (0.95 cm) masonry bit in a hammer drill to cut through your foundation. Hold the drill bit straight against one of your marks on the foundation and turn it on to cut through the concrete. Make the holes about 2 inches (5.1 cm) deep so the anchors can easily fit inside. Continue drilling holes at each of your marks along the foundation wall. Put on a pair of safety glasses so you don't get hurt while drilling the holes. You can use a regular rotary drill, but it will take longer and may damage the machine. Check your local hardware store to see if they rent hammer drills so you don't need to buy one.

Screw the window well into place using masonry anchors. Use masonry anchors that are ⁄8 in (0.95 cm) in diameter and 1 ⁄8 in (4.8 cm) long. Unscrew the nuts from the anchor sleeves and slide the sleeves into the holes you drilled. Position the window well in front of the sleeves and screw the nuts back into the sleeves. Tighten the nuts with a socket wrench so the window well stays firmly in place. You can buy masonry anchors from your local hardware store.Warning: Don't use regular wood screws to mount the window well since they could easily come loose.

Apply a line of caulk around the well if you want additional protection. Caulking around the sides can help seal the window well from water to prevent more leaks. Load the caulk into a dispenser and squeeze the trigger to apply it. Work around the sides of the window well with a thin line of caulk to seal it. You don't need to caulk around the sides of the window well if you don't want to.

Filling in Around the Well

Fill the bottom 2–3 in (5.1–7.6 cm) of the window well with gravel. Pour the gravel around the inside and outside of your window well, and pack it down with the bottom of your shovel. Spread the gravel evenly over the area so you have a 2–3 in (5.1–7.6 cm) layer at the bottom of the hole. Make sure the layer of gravel is lower than the window sill or else it could leak into your home. The gravel will help improve the window well's drainage so water doesn't pool up or flood into your basement.Tip: You can put a layer of landscaping fabric between the dirt and gravel if you don't want them to mix in the future.

Pack dirt around the outside of the well until you fill the hole. Use the dirt you originally dug up around the side of your home to fill in the hole. Pour about 1 foot (30 cm) of dirt along the outside of the well, and press it down with your foot to pack it tightly. Continue alternating between adding 1 foot (30 cm) of dirt and tamping it down so the soil around the well is tightly packed. Leave the top 2–3 inches (5.1–7.6 cm) of the window well exposed so water and dirt can't leak into it. If you can't fit your foot in the hole to pack the dirt in, use a hoe or a tamper to press the dirt down.

Secure a cover on top of the well to prevent anything from getting inside. Get a window well cover that matches the size of your window well and place it over the opening. If you want the cover permanently installed, make holes in your foundation with a hammer drill and a masonry bit before securing the cover in place with anchors. If you don't want it permanently installed, lay a heavy piece of wood or rock on top of the cover so it doesn't blow away. You can buy window well covers from your local hardware or home improvement stores. You don't need to put on a window well cover if you don't want one.