In addition to bringing in sunlight, an egress window serves an essential purpose in emergencies as both an escape from and an entrance to the basement. This function is so important that the 2006 International Residential Code (IRC) requires egress windows in all basements, not just those with bedrooms.
Installing an egress window is a challenging project that is most often handled by a contractor at a cost of $1,500 to more than $5,000, depending on the installation location, size of window and type of well. However, an ambitious and skilled DIYer can tackle the job for about one-third to one-half as much, including materials and tool rental.
Plan and design
Before you begin any basement renovation, you must correct all moisture problems. Once you’re sure the basement will stay dry, make the following decisions:
- Choose the location - Your options of where to install an egress window will likely be limited, especially if the basement is finished or you’re committed to a future floor plan. If possible, consider a south-facing wall for maximum sunlight. Avoid installing the window on the front of the house, and call for an inspection to identify buried utility lines before you make a decision.
- Choose the type of window - An egress window must be large enough (see “Window Size,” in PDF below) for occupants to escape and rescue workers to enter the house, and it must not require tools to open. Sliding windows are commonly used because they are easy to operate and the opening is nearly the full height of the window frame. Casement windows are also a good choice as long as they feature special egress hardware that allows the window to swing open far enough to create a clear escape opening.
Double-hung windows are not typically used in basements because they must be very large to create an adequate-size window opening. An awning window is also not a good choice because the window swings upward and can be an obstruction in the window well.
If you already have a basement awning window, the easiest installation is to replace it with a window that’s the same width. Though a wider window will let in more light, it will also be more work to install.
- Choose the well - Several types of window wells are available. As with the window, a minimum egress-well size is required by the building code (see “Anatomy of an Egress,” in PDF below). Don’t assume that all manufactured window wells meet your city’s interpretation of the building code. Include the manufacturer’s specifications for the well with your building-permit application.
You can build an egress window well using the same materials that you would use to build a retaining wall, such as exterior-grade wood timbers (above), landscape block (below) or natural stone. There are also several styles of manufactured window wells made from molded plastic or galvanized steel that are fast and easy to install.
Digging and drainage
Even a small window well for a single-width window will require removing at least a cubic yard of dirt. If your soil is easy to dig, you might consider digging the hole by hand. In most cases, though, you’ll want an excavator to dig the hole. You can rent a mini-excavator with a trailer for about $250 to $300 per day, or you can hire an excavation contractor to dig the hole. Depending on site access and the size of the hole, you can expect to pay about $500 for a contractor to dig the hole and haul away the excess dirt.
The hole should be about 2 ft. wider than the window well and 6 to 9 in. deeper than the bottom of the window. Keep about one-third to one-half of the dirt to backfill around the well. The rest will need to be disposed of; excavation contractors will haul it away for an additional fee, or you can rent a yard-waste dumpster.
Proper grading and a gutter system will minimize the amount of water that gets into the well. You can also install a hinged cover to deter water, but you’ll still need to create an outlet for the water that does enter.
The best method is to tie into the existing foundation-drain system. Dig a 10-in.-dia. drain hole in the bottom of the well that connects to the exterior drain field. Fill the drain hole with pea-rock or coarse gravel that will not compact. If your house has an interior drain system, the only way to tie into it is to dig the drain hole down below the level of the foundation footings and then dig a tunnel under the foundation to connect the drain field under the basement floor.
If your soil drains well, another option is to dig a drainage reservoir (sometimes called a French drain) in the bottom of the well. This is essentially a 24-in.-deep x 30-in.-dia. hole located away from the foundation and filled with gravel. Any water that goes into the well will be directed into the reservoir and be held there until it dissipates into the soil. Consider installing a sump pump in the reservoir if your soil drains poorly and you can’t tie into an existing foundation-drain system.
The window opening
The most intimidating part of this project is cutting the opening in the foundation wall. Even if you’re doing the rest of the installation yourself, consider hiring a concrete-sawing contractor to cut the opening using a hydraulically driven water-cooled wall saw that has a blade large enough to cut all the way through the foundation from the outside (photo 1). A sawing contractor will likely cost $500 to $600, but this approach offers several advantages. First, it’s safer to let an experienced professional make these cuts. Second, it eliminates most of the inside mess. Third, you can cut the window opening in an interior finished wall just large enough for the window, minimizing interior finish work. And finally, many contractors will haul away the debris.
A wall mounted saw cuts completely through the foundation from the outside. A smaller gas-powered saw (photo 2) can also be used, but cuts must be made from both sides of the wall.
If you prefer, you can cut the hole yourself with a gas-powered concrete saw (photo 2). These saws are not difficult to operate, and renting one will save you money ($75 to $100 a day), but there are a several downsides. First, because the blade diameter on a gas-powered saw is not large enough to cut through the full thickness of the foundation, you must cut from both the inside and the outside, and you must measure and mark cut lines carefully to make sure they line up. Second, gas-powered saws create huge clouds of dust and exhaust fumes. Make sure you have adequate ventilation, wear a respirator for protection, and try to seal off the work area with plastic. Even with a plastic barrier, you’ll find settled concrete dust in your house weeks after the job is done. Third, you’ll have to remove a large portion of any existing interior wall to make the inside cuts in the foundation wall. Finally, it’s slow cutting through a solid poured-concrete foundation wall with a handheld dry-cut saw.
In most cases the mudsill plate that rests on top of the foundation will be the top of the window opening, so only the sides and bottom of the opening need to be cut. Determine the opening size by adding the required window rough opening dimensions to the widths of all of the framing members that will be installed. Your building inspector can tell you whether a header is required over the new window.
After cutting the perimeter of the opening with the saw, break the foundation into pieces and remove them from the opening (photo 3).
Remove the foundation wall after the sides and bottom of the window opening are cut. Use a demolition hammer ($50 to $75 a day to rent) to break the foundation wall into pieces.
To begin installation, frame the window opening with pressure-treated pine. Place shims under the inside edge of the sill to elevate the back edge slightly, creating a pitch toward the outside. Apply silicone caulk between the framing members and the foundation blocks, and secure them to the blocks with concrete nails or screws. Use an engineered beam or three 2x8s stacked on edge as a header.
After the rough frame has been installed, use the frame as a guide for cutting the opening in an interior basement wall. Next, install the window (photo 4). Level and plumb the window in the opening, seal around the perimeter with silicone caulk, fasten the flange to the rough frame, and apply adhesive window-sealing tape around the window.
Level and plumb the window in the opening, seal around the perimeter with silicone caulk, fasten the flange to the rough frame, and apply adhesive window-sealing tape around the edges of the window.
Trim around the exterior of the window with exterior-rated lumber, and trim the interior to match the rest of the basement trim. Use veneered plywood to make the jamb and sill extensions necessary to trim out the extra-deep interior window opening.
Wood and manufactured window wells are attached to the house with concrete fasteners (photo 5). Attach a layer of heavy plastic to the back of wood wells as a barrier against moisture to extend longevity. Fill the bottom of the well with 6 to 9 in. of loose gravel that will not compact, and backfill behind the well walls with soil.
After fastening the sides of this timber well to the foundation with brackets, 1/2-in. lag screws and expanding concrete anchors, the front terrace sections are fastened to the well sides with 3/8-in.-dia. x 8-in.-long lag screws.
Install a ladder if the well is deeper than 44 in. and is not terraced or does not feature built-in steps. Grade the soil away from the house and the well, and landscape around the well with mulch, grass or low plants, making sure that anything you place around the well will not obstruct access in or out.
Getting out of the well
A permanent ladder, steps or terraced levels are required if the well is more than 44 in. deep. The ladder rungs must be at least 12 in. wide and spaced no more than 18 in. apart. The ladder may encroach on the well dimensions by no more than 6 in.
Once the window is installed, you’ll wonder how you lived without it. The daylight and access that it provides will not only make your basement safer but also create a more enjoyable environment that you’ll want to spend more time in.