How to Install a Basement Egress Window

Installing a basement egress window involves cutting through the foundation wall, creating a window well, installing the window frame, and ensuring proper drainage and waterproofing.

1. Get Permits Before You Start. Contact your local building department to understand egress window requirements for your area. Most codes require a minimum opening of 5.7 square feet with a minimum width of 20 inches and height of 24 inches. The window sill cannot be more than 44 inches above the floor. Apply for and receive all necessary permits before beginning work.
2. Mark Openings With Precision. Measure and mark the window opening on both the interior and exterior walls. Use a level to ensure your marks are straight. The opening should be 2-3 inches larger than the actual window frame to allow for proper installation and insulation. Check for utilities like electrical, plumbing, or gas lines that might run through the area.
3. Cut Through Foundation Wall. Rent a concrete saw or diamond blade circular saw designed for masonry. Start cutting from the inside, following your marked lines. Work slowly and use water to control dust. For thick foundation walls, you may need to cut from both sides. Wear safety equipment including eye protection, hearing protection, and a dust mask.
4. Excavate The Window Well. Dig out the exterior area to create the window well. The well should extend at least 8 inches beyond the window frame on all sides and be deep enough so the bottom sits 6-8 inches below the window sill. Slope the bottom away from the foundation for drainage. Remove all debris and loose soil.
5. Secure Window Frame Level. Place the window frame into the opening and check that it sits level and plumb. Use shims to adjust as needed. The frame should sit flush with the interior wall surface. Secure the frame using concrete screws or masonry anchors according to the manufacturer specifications, typically every 12-16 inches around the frame.
6. Waterproof Every Seal. Apply exterior-grade caulk around the entire window frame where it meets the foundation. Install flashing tape over the sill and up the sides of the opening. Apply waterproof membrane or coating to the window well walls. This step is critical for preventing water infiltration.
7. Install Drainage System. Place a corrugated metal or composite window well liner around the excavated area. The liner should extend from below grade to at least 3 inches above the window sill. Install a drain tile system at the bottom of the well connected to your foundation drainage system or a sump pump. Cover the bottom with 4-6 inches of gravel for drainage.
8. Backfill And Finish Interior. Backfill around the window well with gravel and soil, ensuring proper drainage slope away from the foundation. Install the window sash if not already in place. Add insulation around the frame interior and finish the interior wall with drywall or other suitable material. Install trim around the window opening.
9. Install Egress Ladder. If the window sill is more than 6 feet above the well floor, install a permanent ladder or steps to meet egress requirements. The ladder rungs should be at least 12 inches wide with maximum 18-inch spacing. Secure the ladder firmly to the window well or foundation wall.