Replace old windows from measuring and product selection through removal, installation, insulation, and trim finishing for better energy efficiency and comfort.
Last updated:
0 of 27 completed0%
Copied!
Assessment and Planning
Determine which windows need replacement
Signs of failing windows: condensation between panes, drafts with windows closed, difficulty opening/closing, visible rot in wood frames, and high energy bills. Windows over 20 years old with single-pane glass are strong candidates.
Choose between full-frame and insert replacement
Insert (pocket) replacement fits inside the existing frame and costs 30-40% less. Full-frame replacement removes everything to the studs and costs $500-$1,200 per window. Use full-frame if the existing frame is rotted or damaged.
Measure each window opening precisely
Measure width at 3 points (top, middle, bottom) and height at 3 points (left, center, right). Use the smallest measurement for ordering. Measure diagonals to check for square — a difference over 1/4 inch means the opening is out of square.
Record width at top, center, and bottom
Record height at left, center, and right
Set a budget and get quotes
A standard double-hung replacement window costs $300-$700 per window installed. A whole-house project (10-15 windows) runs $5,000-$12,000. Get 3 quotes and compare warranty terms. Most quality windows carry a 20-year warranty on glass seals.
Window Selection
Choose a frame material
Vinyl frames ($200-$500 per window) require zero maintenance and insulate well. Wood frames ($400-$800) look traditional but need painting every 5-7 years. Fiberglass ($500-$900) is the strongest and most durable but costs the most.
Select the right glass package for your climate
Double-pane with low-E coating is the minimum standard. Triple-pane adds 10-15% to the cost but cuts heat loss by 30-50% compared to double-pane. Argon gas fill between panes costs $25-$50 extra per window and improves insulation by 15%.
Choose window style and operation type
Double-hung windows (top and bottom sash slide) are the most common. Casement windows (crank-out) seal the tightest against air infiltration. Fixed (picture) windows cost 20-30% less because they have no moving parts.
Order windows and confirm lead time
Standard sizes ship in 1-3 weeks. Custom sizes take 4-8 weeks. Measure twice before ordering — custom windows are non-returnable. Order all windows at once to get volume pricing and ensure consistent color matching.
Check for energy efficiency rebates and tax credits
Federal tax credits cover up to 30% of window costs (max $600 per year) for qualifying energy-efficient windows. Many utilities offer $50-$100 rebates per window. Keep all receipts and manufacturer specification sheets for your tax filing.
Removal of Old Windows
Remove interior trim and stops
Score the paint line with a utility knife to prevent wall damage. Use a thin pry bar and work slowly. Number each trim piece with pencil on the back for reinstallation. Old stops are usually damaged during removal — budget $2-$4 per foot for new ones.
Remove the old sash and hardware
Double-hung windows: cut the sash cords (or disconnect spring balances), tilt the sash in, and lift out. Casement windows: disconnect the operator arm and lift the sash off its hinges. Save hardware if it's in good condition.
Clean and inspect the window frame
Remove old caulk, paint, and debris from the frame. Probe wood with an awl — if it sinks more than 1/4 inch, the wood is rotted. Small rot spots can be filled with epoxy ($15-$25/quart). Extensive rot means full-frame replacement is needed.
Check the rough opening for square and level
Measure the diagonals of the rough opening — they should be within 1/4 inch. Check the sill for level. Shim any low spots before setting the new window. An out-of-square opening causes binding, leaking, and premature hardware failure.
Installation
Apply waterproof flashing tape to the sill and jambs
Apply 6-inch-wide self-adhesive flashing ($15-$25 per roll) to the sill first, then up the jambs, then across the head. Overlap each piece by 2 inches. This is the primary water defense — skip it and rain will enter the wall cavity.
Dry-fit the new window before fastening
Set the window into the opening and check for plumb (vertical) and level (horizontal). There should be 1/4-inch gaps on each side and top for shimming. If the window doesn't fit, identify the issue before applying caulk or screws.
Apply sealant and set the window
Run a continuous bead of silicone sealant along the sill and up each side of the opening. Set the window into the sealant and press firmly. The sealant creates a waterproof seal between the window frame and the rough opening.
Shim and fasten the window
Place shims at each screw location and behind each hinge point. Drive screws through the shims into the framing. Check operation after every 2 screws — over-tightening warps the frame and causes the window to bind.
Shim at all 4 corners and every 12 inches
Test window operation before final tightening
Insulate the gap between window and rough opening
Use low-expansion spray foam designed for windows ($8-$12 per can). Standard expanding foam exerts too much pressure and can bow the frame. Fill the gap to about 50% — the foam expands to fill the rest. One can does 3-5 windows.
Trim and Finishing
Install interior trim and casing
Standard window casing is 2.25-3.5 inches wide. Nail casing into the wall framing and jamb with 2-inch finish nails. Leave a 1/8-inch reveal (offset) from the jamb edge for a shadow line. Miter corners at 45 degrees for a clean joint.
Caulk exterior trim and flashing
Use paintable exterior silicone caulk ($5-$7 per tube) on all exterior joints. Do NOT caulk the bottom edge — this must remain open for water drainage. Smooth caulk lines with a wet finger within 5 minutes of application.
Paint or stain interior trim
Prime bare wood trim before painting. Apply 2 coats of semi-gloss for durability. Allow 2 hours between coats. For stained trim, apply 2 coats of polyurethane. A pint of trim paint ($8-$12) covers 3-4 windows.
Test all windows for proper operation and sealing
Open and close each window 5 times to confirm smooth operation. Lock and unlock them. Check the weatherstripping contact by closing a dollar bill in the window — you should feel resistance when pulling it out. No resistance means a poor seal.
Clean new glass and remove manufacturer labels
Remove stickers within 30 days — adhesive hardens and becomes difficult to remove after that. Clean with glass cleaner and a lint-free cloth. Some low-E coatings scratch easily — avoid abrasive pads or razor blades on coated surfaces.
Frequently Asked Questions
How much does it cost to replace one window?
A single double-hung vinyl window costs $300-$700 installed for a standard size (30x48 inches). Wood-framed windows run $600-$1,200, and fiberglass costs $500-$1,000. Specialty windows like bay or bow windows cost $1,500-$4,000 each. Full-house window replacement (15-20 windows) ranges from $8,000-$20,000. Prices include the window, labor, trim, and disposal of the old window.
How do I know when windows need to be replaced?
Key signs include drafts you can feel near closed windows, condensation or fog between double-pane glass (indicating a failed seal), difficulty opening or closing, visible wood rot on frames, and notably higher energy bills. Single-pane windows from before 1980 are strong candidates for replacement. You can test for air leaks by holding a lit candle near the window frame on a windy day and watching for flame movement.
Do new windows really save money on energy bills?
Replacing single-pane windows with Energy Star-rated double-pane windows saves $101-$583 per year on energy bills, according to Energy Star estimates. The exact savings depend on your climate zone, home size, and how many windows you replace. In cold climates, Low-E glass with argon gas fill reduces heat loss by 30-50%. The energy payback period is 10-20 years for most homes, but the comfort improvement is immediate.
What is the difference between full-frame and insert window replacement?
Insert (pocket) replacement fits a new window into the existing frame, costs 20-30% less, and takes 30-60 minutes per window. Full-frame replacement removes everything down to the rough opening, costs more, and takes 2-4 hours per window. Use insert replacement when the existing frame is in good condition and square. Choose full-frame when the frame is rotted, damaged, or you want to change window sizes. Most replacement projects use the insert method.
Are vinyl or wood windows better?
Vinyl windows cost 30-50% less, need zero painting or staining, and resist moisture and rot. Wood windows offer a more traditional look, can be painted any color, and provide slightly better insulation (R-value of 1.5-2.0 vs. vinyl at 0.5-1.0 per inch). Fiberglass is a middle ground at 20% more than vinyl with superior strength and paintability. For most homeowners, vinyl provides the best value. Wood is the better choice for historic homes or when matching an existing aesthetic.