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How to Install a Terraced Window Well in Your Basement

Bring a flood of light into a dreary basement with a terraced window well. You also get an emergency escape route, planting beds and a view. Build this well as part of an egress window project or simply landscape an existing window well. In this article, we'll walk you through the construction process and tell you how to deal with the all-important issue of drainage.

By the DIY experts of The Family Handyman Magazine

  • ComplexityComplexityComplexity Moderate
  • close X

    The techniques only require simple carpentry skills. But you need a strong back for the digging and hauling.

  • COST
  • CostCostCostCost Over $500
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    Using timbers this project cost about $500. Costs would rise with decorative concrete blocks. Add $200 if you have to rent a trash container to get rid of excess soil.

Design for safety

The primary rules for designing a window well are the code requirements for an egress window. The bottom of the well must be at least 3 x 3 ft., the well can't interfere with opening the window, and you have to provide a permanent ladder if the walls are more than 44 in. high. Terracing our well eliminates the ladder requirement.

Otherwise, you're only limited by safety and drainage issues. Any window well is inherently dangerous because of the potential for falls. Covered window wells are safest, but you can't let the cover hinder the window operation and it must be easily removable (without tools) to provide easy egress and emergency escape.

Terracing minimizes the danger of a fall. We recommend that you construct the widest terraces and lowest steps that your site will allow. You could also put a railing around the well, a feature we recommend if you have a walk nearby. The window well we're building opens onto a spacious yard, away from walkways.

Still, we took the extra precaution of adding a curb about 8 in. above grade plus flower beds and low bushes to keep folks from stepping into it. We constructed our terraced well with 4x6 treated wood timbers because they're long lasting, easy to cut and level, and economical. To dress up the timbers, we stained all sides before installation with an oil-based semi-transparent redwood stain.

Decorative concrete wall block is another good choice for terracing. This block will last forever, but it's about twice as expensive as wood and harder to cut and assemble. Another option is to buy a manufactured well. These range from the corrugated steel culvert style (available in most home centers) to manufactured terraced wells.

Good drainage is critical

If your basement hasn't suffered any moisture or flooding problems, digging a window well or expanding an existing well is unlikely to create water problems, as long as you follow the instructions in the photos. The two sizes of gravel we show provide a path for water to easily flow down into the soil without filling up the well. The landscape fabric acts as a filter to prevent soil from clogging the gravel drain field.

Soil with a high clay content, however, poses another problem. This soil tends to trap water instead of letting it drain away. For yards with clay soil or poor drainage, or for damp basements, consult a professional before undertaking the project. (Check the Yellow Pages under “Waterproofing Contractors.”)

One option to ensure good drainage is to tie the well's drain field into the existing drainage system around the footing of your basement (Fig. A). If you don’t know if you have foundation drains, you'll have to call the builder or the city department of inspections, or dig down to the footing at the bottom of the wall and look for a gravel bed with a plastic or other type of pipe. If you find the pipe, simply fill the hole with 3/4-in. gravel to connect the two drain fields.

Some homes have drains on the interior, under the basement floor, and rely on a sump pump to get rid of water. Connecting to this type of system is more complicated and difficult. We suggest that you leave this work to a pro.

Be sure to show your plan to your local building inspector and obtain a permit. Ask about any special requirements and discuss drainage issues. The inspector should be familiar with local soil conditions.

Step 1: Dig and prep the hole

Photos 1-4 walk you through the steps for digging the well. Fig. A shows you the exact dimensions we used, but you can easily adjust them to fit your site. Your layout doesn't have to be precise; a stake centered on the window will be accurate enough for digging (Photo 1).

To build the size well we show here, you'll be removing a small mountain of dirt (more than 8 cu. yds.). Save your topsoil, but get rid of the rest of the dirt by renting a 20- or 30-yd. trash container. The oversized container gives you a large base so you don’t have to pile the dirt so high.

Make sure the trash container has a gate on the back that you can swing open for the wheelbarrow. Tell the waste company that you'll be loading dirt in the container so it's aware of the weight involved. If you have to put the container curbside, you'll probably have to get a permit from the police department.

We built our entire well first, then added the window. But it's easier to cut in your egress window after you're done with the initial digging (Photo 2). Then finish the well.

TIP: Cover the excavation during rainy periods to keep water out and keep the walls from eroding.


Before doing any digging, always call your local utility companies (Natural gas, Water, Electric, Phone and Cable) to locate buried lines.

Step 2: Set the first row of timbers

With the bottom level and the window accurately marked, lay out your wall pattern. Then measure the lengths and angles of the timbers and cut them (Photo 5). Often, the cuts expose untreated wood, so treat raw ends after cutting (Photo 6). Use a wood preservative containing copper (available at paint stores, hardware stores or home centers). Set the first row of timbers perfectly level (Photo 7).

Step 3: Set and fasten the remaining levels

The process for the second row is exactly the same as for the first (Photos 8 – 11). Driving the spikes takes some effort, so be sure to predrill with a 12-in. bit (Photo 9). One good reason to backfill with gravel is to avoid the need for compacting (Photo 11). Backfilling with soil would require a lot of tamping to keep it from settling over the next year or two. Complete and backfill all the levels.

Step 4: Anchor the walls at the foundation

Photos 12 and 13 show you how to anchor the timbers against the foundation. Once you finish the well, scatter decorative stone over the surfaces to spruce up its appearance. If you decide to add plants, confine them to pots nestled into the gravel. That way soil won't clog up the drainage. Or encourage vines to grow over the top and down the sides. But leave an uncluttered pathway open for emergency escape.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

    • Hammer
    • 4-lb.
    • Tape measure
    • Circular saw
    • Caulk gun
    • Corded drill
    • Level
    • Drill bit set
    • Garden rake
    • Wheelbarrow
    • Safety glasses
    • Sawhorses
    • Spade
    • Speed square
    • Paintbrush
    • Utility knife
Rubber gloves
3/8-in. drill bit, 12-in. long
5/16-in. masonry bit

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

    • 4 x 6 treated timbers
    • 3/4-in. gravel
    • Pea gravel
    • Spray paint
    • Plastic tarp
    • Plastic sheeting, 4 mil.
    • Landscape fabric
    • Fabric spikes
    • Exterior stain
    • Wood preservative
    • 3/8-in. x 10-in. spikes
    • 3-in. deck screws
    • 1/4-in. x 1-1/2-in. concrete screws
    • Silicone caulk

Comments from DIY Community Members

Share what's on your mind and see what other DIYers are thinking about.

1 - 5 of 5 comments
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May 14, 11:12 AM [GMT -5]

I wanted to know what is used for covering the window well -- winter in WI would mean it would fill up with snow otherwise. Not desirable

September 16, 7:25 AM [GMT -5]

Great overview of terraced window-well.

One small material change I would recommend is switching to a 50-year polyurethane sealant as it will give a longer life and better performance than the silicone in this situation.

Project on...

April 02, 4:49 PM [GMT -5]

Great Idea from Family Handman Magazine. When we built our house, I had used this very same design to place a terraced window well in out basement. Since it was new construction, I was able to have the concrete contractor frame the opening for our window size.

The installation is pretty straight forward as the article suggests with a couple of hints. First off, I would not recommend a casement window in this design for a couple of reasons. First, if you live in a northern state where is snows, you may not be able to open your window in an emergency. Second, the design of a casement window leaves the window susceptible to damage by standing snow in the window well. How do I know this...it happen to me. Our house has complete casement windows by Pella. I ordered an exact window for the basement so they would all match. After 5 years, the window started to swell and needed to be replaced. The window was under warranty which was great, however, I decided to replace the window with a slider to alleviate the snow hazard.

The only other consideration is that you may be required to place a fence around your window well. We were able to use a low (24") garden fence and landscaping to satisfy the building department as they were concerned with someone falling into the hole.

January 16, 2:19 PM [GMT -5]

The timing was excellent. Completion of the project comes when the weather cooperates. Our existing terraced window well, installed as a part of construction, is showing signs of needing replacement.

Our existing well has one terrace. I think the design you have is more appealing and provides an easier egress, if it's ever needed.

I'll let you know how my project works out.

Don Schmidt
Fargo ND


April 19, 3:01 PM [GMT -5]

Thanks for posting this! That is definitely a way to remodel your basement window well, I have to say. Great pictures too! I love this project. Thanks, Castle - http://andersoncovers.com -

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