In this guide
Installation matters as much as the window
Many window problems people blame on the product, like drafts, condensation around the frame, sticking sashes and water stains on the sill, actually come from installation. A window that isn't level, plumb and square won't operate smoothly, and gaps that aren't properly insulated and flashed let in air and water.
That's why choosing an installer deserves as much attention as choosing a brand. Manufacturer warranties often depend on correct installation too.
Questions to ask every contractor
Use these questions to compare companies on more than price:
- Are you licensed and insured, and can I see proof?
- Do your own trained crews install, or do you subcontract?
- Will you do insert (pocket) or full-frame installation, and why?
- How will you flash, insulate and seal each opening?
- What happens if you find rot in the frame or sill?
- What does your workmanship warranty cover, and for how long?
- Who do I call if there's a problem after installation?
- Can you provide references from recent window customers nearby?
Red flags to watch for
High-pressure sales tactics are the biggest warning sign. 'Today-only' pricing, an inflated list price followed by a dramatic discount, or a salesperson who won't leave without a signature are all reasons to slow down. A reputable company will give you a written quote that holds for a reasonable period.
Be cautious of quotes that are dramatically lower than others, vague descriptions like 'install windows' with no product details, requests for full payment up front, or a contractor who doesn't measure the openings themselves.
Compare quotes apples to apples
Window quotes can differ in ways that aren't obvious. Make sure each one specifies the window series, frame material, glass package (low-E type, gas fill, number of panes), grid style, color, hardware and screens. It should also state the installation method, interior and exterior trim work, capping or wrapping of exterior frames, disposal of old windows and permit costs.
If one quote is for full-frame replacement with new exterior trim and another is for a simple insert installation, they aren't comparable. Ask each contractor to explain why they recommend their approach for your home.
What a quality installation includes
When you're comparing contractors, ask them to walk you through their process. A careful installation generally includes:
- Protecting floors and furnishings with drop cloths
- Careful removal of old sashes or frames without damaging interior trim
- Inspecting and repairing the rough opening and sill
- Proper flashing and sill pans to direct water outward
- Low-expansion foam or insulation to fill gaps without bowing the frame
- Checking that sashes operate and lock smoothly before trim goes on
- Exterior sealing and capping, then a thorough cleanup
After the job
Before your installer leaves, open, close and lock every window. Check for gaps in trim and caulk. Keep warranty registrations, product labels and your invoice together. A good contractor will follow up to make sure everything is working and will respond promptly if something needs adjusting.