Start with a home inspection and written measurements
Before you contact a single contractor, walk through your home and decide which windows need replacing. Look for visible damage: cracked or broken glass, frames that won't open or close smoothly, condensation between panes, or water stains on the sill or wall. Write down the location of each window (living room, master bedroom, kitchen) and whether it's a single-hung, double-hung, sliding, or casement type.
Measure each window opening from the inside, taking the width at three points (top, middle, bottom) and the height at three points (left, center, right). Write these measurements on a diagram of your home, or take a photo of each window with the measurements written on a piece of paper held in front of it. Contractors will remeasure, but your notes help you spot mistakes and compare quotes accurately.
Key Takeaways
- Measure each window opening yourself before contacting contractors, recording width and height at three points on each window to catch errors in their quotes.
- Get written quotes from at least three contractors that specify the window brand, frame material, glass type, labor cost, and removal of old windows.
- Check references and verify licensing and insurance before signing a contract, and never pay the full amount upfront.
- Schedule the work during dry weather and plan for noise, dust, and limited access to rooms during installation, which typically takes one to three days per window.
- Keep all receipts, warranties, and the contractor's contact information in one folder for future reference or warranty claims.
Gather quotes from multiple contractors with the same specifications
Contact at least three window contractors in your area and ask each one to visit your home for an in-person estimate. Bring your measurements and notes to the meeting. A contractor should measure the openings themselves, but your notes let you verify their work and compare quotes side by side.
Ask each contractor to provide a written quote that includes the window brand and model, frame material (vinyl, wood, aluminum, fiberglass), glass type (single-pane, double-pane, low-E coating), the cost of labor, and whether removal of old windows is included. If the quote doesn't specify these details, ask for them in writing before you decide. A vague quote makes it impossible to compare one contractor against another.
Request references from at least two recent jobs in your area. Call those homeowners and ask whether the work was completed on time, whether the contractor cleaned up afterward, and whether any problems came up after installation. Ask about the warranty and whether the contractor honored it.
Verify licensing, insurance, and warranty terms before signing
Before you sign a contract, confirm that the contractor holds a current business license in your state or county. You can usually check this on your state's licensing board website or by calling your local building department. Ask the contractor for proof of general liability insurance and workers' compensation insurance, and verify the coverage amounts are adequate for your project.
Read the warranty section of the contract carefully. Most window manufacturers offer a warranty on the windows themselves (often 10 to 20 years), and the contractor may offer a separate warranty on the installation labor (often one to five years). Understand what each warranty covers, what it does not cover, and how to file a claim if something goes wrong after the work is done.
Never sign a contract that requires you to pay the full amount upfront. Standard practice is a deposit (usually 25 to 50 percent) when you sign, a second payment when the contractor arrives to begin work, and the final payment only after the job is complete and you have inspected it. If a contractor demands full payment before starting, find a different contractor.
Plan the timeline and prepare your home
Window replacement typically takes one to three days per window, depending on the size, the number of windows, and how difficult the old frames are to remove. Ask the contractor for a specific start date and an estimate of how many days the work will take. Plan for noise from power tools, dust from removing old frames, and temporary loss of weatherproofing while windows are being replaced.
Schedule the work during dry weather if possible. Rain can delay the job and damage interior walls if water enters during installation. Avoid scheduling during extreme heat or cold, which can affect how sealants cure and how the new frames fit.
Before the contractor arrives, clear the area around each window inside and outside. Move furniture, curtains, and decorations away from the windows. If you have pets or small children, arrange for them to be elsewhere during the work, or plan to keep them in a separate room away from the noise and dust.
Inspect the work before making the final payment
When the contractor finishes, walk through your home with them and inspect each window. Check that the windows open and close smoothly, that the glass is clean and undamaged, and that the frames are level and find. Look for gaps between the frame and the wall, which should be sealed with caulk or foam. Check that the sills are sloped slightly outward so water runs away from the house.
Ask the contractor to demonstrate how to operate each window type and show you any new locks, screens, or hardware. Request a written list of what was installed, the serial numbers of the windows, and the start and end dates of the work. Do not make the final payment until you are satisfied with the work and have received all documentation.
Organize paperwork and warranty information
Create a folder (physical or digital) and keep all receipts, invoices, the signed contract, the warranty documents, and the contractor's contact information in one place. Take photos of each new window from inside and outside, and save them with the date. If a problem comes up later, you will have proof of what was installed and when.
Register the windows with the manufacturer if they offer a warranty registration program. Some manufacturers require registration within a certain time frame to honor the full warranty. Keep the registration confirmation in your folder as well.
Frequently Asked Questions
How much does window replacement usually cost?
Cost varies widely based on the number of windows, the type of frame material, the glass quality, and your location. Vinyl windows are typically the least expensive, while wood and fiberglass are more costly. Labor costs also vary by region. Your written quotes will show the actual cost for your specific project and location.
Can I replace windows myself instead of hiring a contractor?
Window installation requires precise measurement, proper sealing, and knowledge of building codes. Mistakes can lead to water leaks, drafts, and structural damage. Unless you have experience with carpentry and weatherproofing, hiring a professional contractor is safer and more reliable than a DIY approach.
What should I do if a window leaks after installation?
Contact the contractor when ready and describe the problem in detail. Most contractors offer a labor warranty that covers installation defects. Take photos of the leak and document when it occurs (during rain, wind, or both). If the contractor does not respond or refuses to fix it, contact the window manufacturer, as the defect may be covered under their warranty instead.
Do I need a building permit for window replacement?
Permit requirements vary by city and county. Some areas require a permit for any window replacement, while others do not. Ask your contractor whether a permit is needed in your area, or call your local building department directly. The contractor should handle the permit process if one is required.
How long do new windows last?
Most modern windows last 15 to 30 years depending on the material, climate, and how well they are maintained. Vinyl windows typically last 20 to 25 years, while wood and fiberglass can last longer with proper care. The warranty documents will specify the expected lifespan for your specific windows.