Install Egress Window
Transform a wall into an emergency exit and light source. Proper installation ensures safety, weatherproofing, and years of trouble-free operation.
Why Proper Installation Matters
An egress window is a critical life-safety feature - it's your escape route in an emergency. Beyond safety, cutting a hole in your home's exterior envelope creates potential for water infiltration, air leaks, and structural issues if done incorrectly. Proper framing ensures structural integrity, proper flashing prevents leaks, and careful installation guarantees the window operates correctly when you need it most. This is one project where doing it right matters more than doing it fast.
Tools & Materials You'll Need
Step-by-Step Guide
Mark the Opening Location
Transfer your planned window location to the wall:
- Review window manufacturer rough opening specifications
- Mark opening outline on interior wall at planned sill height (max 44")
- Use level and square to ensure lines are true
- Drill pilot holes through corners to exterior
- Verify location from outside - check for obstructions
Before Cutting: Verify no electrical wires, plumbing, or HVAC runs through the wall section. Use a stud finder and check from both sides.
Cut the Opening
Remove wall materials to create the rough opening:
Safety First:
- * Wear safety glasses and hearing protection
- * Support any studs you'll cut with temporary bracing
- * Have helper catch cut materials from falling
- * Check weather - don't leave opening exposed to rain
- Remove interior drywall within marked area
- Cut studs at header and sill height (save for blocking)
- Cut through exterior sheathing from inside using pilot holes as guide
- Remove siding carefully - you may reuse around window
- Clean up edges for straight, square opening
Frame the Rough Opening
Build structural framing to support the window:
Framing Components:
- *King studs: Full-height studs on each side of opening
- *Jack studs: Support header, nailed to king studs
- *Header: Double 2x lumber spanning opening (size per span)
- *Sill plate: Horizontal member at bottom of opening
- *Cripple studs: Short studs above header and below sill
Pro Tip: Check rough opening is square by measuring diagonals - they should be equal. Shim if needed before installing window.
Install Weather Barrier and Flashing
Proper flashing prevents water infiltration - this step is critical:
- Cut housewrap in inverted Y pattern at top, fold flaps inside
- Install sill pan (flexible membrane or rigid pan) sloped to exterior
- Apply flashing tape to sill, overlapping sill pan
- Apply flashing tape to jambs, overlapping sill tape
- Leave head flashing for after window installation
Flashing Sequence: Always work from bottom up, with upper layers overlapping lower layers like shingles. Water must shed outward at every joint.
Install the Window
Set the window carefully for proper operation:
- Dry fit window in opening - verify fit with 1/4" gap on all sides
- Apply continuous bead of caulk to back of mounting flange
- Set window in opening from exterior, centering in rough opening
- Have helper inside insert shims at jambs and sill
- Check level, plumb, and square - adjust shims as needed
- Secure with screws through mounting flange or pre-drilled jamb holes
- Verify window operates smoothly before final fastening
Don't Overtighten: Screwing mounting flanges too tight can bow the frame and prevent smooth operation. Snug is sufficient.
Complete Weatherproofing and Trim
Finish the installation for weather protection and appearance:
Exterior Finishing:
- * Apply head flashing over top flange
- * Fold housewrap over head flashing
- * Install exterior trim or J-channel
- * Caulk all joints with exterior caulk
- * Install siding to meet trim
Interior Finishing:
- * Insulate gap with low-expansion foam
- * Install interior extension jambs if needed
- * Add window casing and trim
- * Caulk trim to wall and window
- * Paint trim to match interior
Pro Tips
- ✓Use low-expansion foam designed for windows - regular foam can bow the frame
- ✓Install window on a dry day with moderate temperatures for best caulk adhesion
- ✓Leave protective film on window glass until all construction is complete
- ✓Test window operation multiple times before and after foam cures
- ✓Take photos of flashing installation for inspection and future reference
Frequently Asked Questions
How much does it cost to install an egress window in an attic?▼
Professional egress window installation in an attic typically costs $1,500-4,000, depending on window size, wall type, and complexity. This includes the window ($300-1,000), framing materials ($100-300), and labor ($800-2,500). DIY installation can save $800-1,500 in labor costs.
Can I install an egress window myself?▼
Yes, experienced DIYers can install an egress window. You need carpentry skills for framing, knowledge of proper flashing techniques, and ability to work safely at heights. The work requires cutting through exterior walls, which demands precision to avoid structural issues and water infiltration.
What size rough opening do I need for an egress window?▼
Rough opening size depends on your specific window. Generally, add 1/2 inch to each side of the window frame dimensions. For a 36x48 inch window, you typically need a 37x49 inch rough opening. Always verify with the manufacturer's specifications for your exact window model.
Do I need a permit to install an egress window?▼
Yes, egress window installation typically requires a building permit as it involves structural modifications and life-safety features. The permit process ensures the installation meets building codes. Inspectors will verify proper framing, flashing, and that the window meets egress requirements.