Install Windows and Exterior Doors
Close in your building envelope with properly installed windows and exterior doors. Quality installation with correct flashing and air sealing is essential for energy efficiency, comfort, and long-term durability.
Quick Summary
Typical Cost
$8,000 - $40,000
Whole home replacement
Time Required
2 - 5 days
Professional installation
Difficulty Level
Intermediate to Professional
DIY possible with experience
Why This Matters
Windows and exterior doors are among the most important components of your home's building envelope. They control heat transfer, allow natural light, provide ventilation, and are often the weakest points for air and water infiltration. During a whole home remodel, replacing or upgrading these components significantly impacts comfort, energy bills, and long-term maintenance.
Modern windows offer dramatically improved energy performance over units from even 15-20 years ago. Low-E coatings, multiple panes with gas fill, and improved frame designs can reduce heating and cooling costs by 20-30% compared to single-pane or older double-pane windows. This energy savings continues for the life of the windows.
Equally important is proper installation. The best windows in the world will fail if improperly installed. Incorrect flashing allows water into wall cavities, causing rot and mold. Poor air sealing creates drafts and energy loss. Taking time to install windows and doors correctly protects your investment and ensures they perform as designed.
Step-by-Step Guide
Step 1: Plan and Select Products
Window and door selection should happen early in your remodel process as lead times can be 4-8 weeks for custom sizes or specialty products.
- Determine which windows and doors need replacement versus repair
- Consider changing window sizes or locations during remodel
- Research frame materials: vinyl, wood, fiberglass, aluminum, composite
- Compare energy ratings using U-factor, SHGC, and ENERGY STAR certification
- Match window styles to your home's architecture
- Order products with adequate lead time before installation date
Step 2: Measure and Verify Rough Openings
Accurate measurements are critical. Verify rough opening sizes after framing is complete and before ordering custom windows.
- Measure width at top, middle, and bottom of opening
- Measure height on left side, center, and right side
- Check that opening is square by measuring diagonals
- Verify rough openings match window specifications (typically 1/2 inch larger each side)
- Identify any openings that need adjustment before window delivery
- Note sill height from floor for each opening
Step 3: Remove Existing Windows and Doors
For replacement projects, carefully remove existing units and prepare openings for new installation.
- Remove interior trim carefully if you plan to reuse it
- Cut caulk and paint seals around window frames
- Remove sashes first, then jambs and frames
- Pull all old nails and screws from rough opening
- Inspect rough opening framing for rot or damage
- Replace any damaged framing members before proceeding
Step 4: Prepare Weather Barrier
Proper weather barrier installation is the foundation of a leak-free window installation.
- Install housewrap across wall surface if not already present
- Cut housewrap at window opening with modified I-cut (diagonal bottom corners)
- Fold bottom flap into opening and staple to interior of sill
- Fold side flaps back and tape temporarily
- Install sill pan flashing across bottom of opening
- Ensure sill pan has back dam and drains to exterior
Step 5: Install Windows
Window installation requires care to ensure level, plumb operation and proper drainage.
- Apply continuous bead of sealant to back of mounting flange or blind stop
- Set window in opening, centering side to side
- Shim bottom of window to level, maintaining 1/4 inch gap to rough sill
- Check level at sill and plumb at both jambs
- Drive fasteners through mounting flanges, starting at corners
- Check window operation before driving all fasteners
Step 6: Flash and Seal Window Exterior
Proper flashing sequence ensures water drains away from the window rather than into the wall cavity.
- Apply self-adhering flashing tape to jamb flanges first
- Extend jamb tape 2 inches past corners at top and bottom
- Apply head flashing tape overlapping jamb tape
- Fold housewrap side flaps over jamb flashing and tape
- Fold down head flap of housewrap and tape in place
- Leave bottom open for drainage (do not tape sill)
Step 7: Install Exterior Doors
Exterior doors follow similar principles to windows but require additional attention to threshold and security.
- Install sill pan flashing with back dam extending up jambs
- Apply sealant under threshold and set door in opening
- Shim hinge side first, checking for plumb
- Secure hinge side with structural screws (at least 3-inch into framing)
- Adjust strike side for proper reveal and latch operation
- Verify door swings freely and weatherstripping seals properly
Step 8: Air Seal Interior
Interior air sealing is often overlooked but is essential for energy performance and preventing condensation.
- Apply low-expansion foam around entire window perimeter
- Use foam designed for windows and doors (not high-expansion)
- Fill gap completely but do not overfill (can bow frame)
- Apply backer rod and caulk at door threshold to subfloor connection
- Verify no daylight visible around any frames
- Consider tape or liquid-applied air barrier at jamb to drywall transition
Step 9: Install Interior and Exterior Trim
Trim covers gaps and provides finished appearance. Installation can happen now or after drywall and painting.
- Install exterior trim or J-channel for siding interface
- Caulk all exterior trim joints with paintable exterior caulk
- Install interior extension jambs if needed (common with thick walls)
- Install interior casing trim after drywall is complete
- Install window stools and aprons at interior
- Caulk interior trim to drywall joints before painting
Step 10: Final Inspection and Testing
Verify all windows and doors are properly installed and functioning before closing up walls.
- Test operation of all sashes, locks, and hardware
- Check that screens fit properly if included
- Verify weatherstripping seals against frames on all sides
- Look for daylight around frames indicating air leaks
- Inspect exterior flashing for completeness
- Schedule inspection if required by local building department
Window Frame Materials Comparison
Vinyl Windows
The most popular choice for replacement windows, offering good value and low maintenance.
- Cost: $300-700 per window installed
- Lifespan: 20-40 years
- Pros: Low maintenance, affordable, good insulation
- Cons: Limited colors, can warp in extreme heat
Wood Windows
Traditional choice offering beauty and design flexibility with higher maintenance requirements.
- Cost: $600-1,200 per window installed
- Lifespan: 30-50+ years with maintenance
- Pros: Beautiful, paintable, excellent insulation
- Cons: Requires painting/staining, can rot
Fiberglass Windows
Premium option combining strength, stability, and energy efficiency.
- Cost: $700-1,500 per window installed
- Lifespan: 40-50+ years
- Pros: Strong, stable, slim profiles, paintable
- Cons: Higher cost, fewer style options
Composite/Clad Windows
Wood interior with aluminum or vinyl exterior cladding for best of both worlds.
- Cost: $800-1,800 per window installed
- Lifespan: 40-50+ years
- Pros: Beautiful interior, weather-resistant exterior
- Cons: Premium price, complex construction
Cost Breakdown
Pro Tips
Understand Energy Ratings
U-factor measures heat transfer (lower is better). SHGC measures solar heat gain (lower in hot climates, higher in cold). Look for ENERGY STAR certification for your climate zone. The NFRC label provides standardized ratings for comparison shopping.
Order All At Once
Order all windows and doors from the same manufacturer in the same order. This ensures color matching (especially for vinyl) and simplifies warranty coverage. Volume orders often qualify for contractor pricing even through retail channels.
Inspect Before Installing
Check all windows and doors for damage before installation. Verify sizes match rough openings. Look for cracked glass, damaged frames, and missing hardware. It is much easier to resolve issues before installation than after.
Do Not Over-Shim
Use only the minimum shimming needed to make the window level and plumb. Over-shimming bows the frame, causing binding and operation problems. If excessive shimming is needed, the rough opening should be adjusted instead.
Use Low-Expansion Foam
Standard expanding foam can bow window and door frames, causing operation problems. Always use foam specifically designed for windows and doors (low-expansion). Better yet, use backer rod and caulk at critical areas and foam only in hidden cavities.
Consider Security
Entry doors should have solid cores (steel or fiberglass over foam) and reinforced strike plates with 3-inch screws into framing. Consider smart locks for convenience and monitoring. Ground-floor windows may benefit from laminated glass for security.
Common Mistakes to Avoid
Improper Flashing Sequence
The most common window installation failure is incorrect flashing. Water must shed in shingle fashion: head flashing over jamb flashing, jamb flashing over sill pan. Taping in the wrong order creates water traps that lead to rot and mold. Never tape or caulk the sill (water must drain out).
Skipping the Sill Pan
Window sills are the most vulnerable to water entry. A sill pan with back dam and end dams catches any water that penetrates and directs it to the exterior. Skipping this step is the leading cause of window-related water damage. Always install a sill pan, whether formed from flashing tape or a pre-formed product.
Wrong Rough Opening Size
Openings that are too small require difficult rework. Openings that are too large require excessive shimming and create weak points. Measure twice and verify against window specifications before ordering. Standard is 1/2 inch larger on each side, but always check manufacturer requirements.
Not Testing Before Final Fastening
Install just enough fasteners to hold the window in place, then test all sashes and locks before driving the remaining fasteners. Windows that bind or do not latch properly need adjustment. Once all fasteners are set, adjustment becomes much more difficult.
Forgetting Interior Air Sealing
Even with perfect exterior flashing, windows will underperform if the interior gap is not air sealed. Use low-expansion foam around the entire perimeter. This prevents drafts, reduces energy loss, and prevents warm moist interior air from condensing inside the wall cavity.
Frequently Asked Questions
What is the best window type for energy efficiency?
Triple-pane windows with argon or krypton gas fill and low-E coatings offer the best energy efficiency, with U-factors as low as 0.15-0.20. For most climates, double-pane low-E windows with U-factors around 0.25-0.30 provide excellent efficiency at lower cost. Look for ENERGY STAR certification appropriate for your climate zone.
Should I choose vinyl, wood, or fiberglass windows?
Vinyl windows offer the best value with low maintenance and good insulation. Wood windows provide superior aesthetics and can be painted to match any style but require ongoing maintenance. Fiberglass windows combine durability, energy efficiency, and a slimmer profile but cost more. Composite (wood interior/aluminum exterior) offers the best of both worlds for premium projects.
How do I properly flash a window installation?
Proper flashing follows a specific sequence: First, install sill pan flashing across the bottom of the opening. Then apply housewrap with the bottom cut and folded into the opening. After the window is installed, apply self-adhering flashing tape to the jambs, then the head, overlapping in shingle fashion. This sequence ensures water drains out rather than into the wall cavity.
What size rough opening do I need for a window?
Standard rough openings are 1/2 inch larger than the window frame on each side and top (1 inch total wider, 1/2 inch taller). For example, a 36x48 window typically needs a 37x48.5 inch rough opening. Always verify manufacturer specifications as requirements vary. Too tight causes installation problems; too loose requires excessive shimming.
Can I install windows and doors myself?
DIY installation is possible for experienced homeowners, but professional installation is recommended for several reasons: manufacturer warranties often require professional installation, improper flashing causes costly water damage, and installation errors affect energy performance. If you DIY, carefully follow manufacturer instructions and local code requirements for air sealing and flashing.