# 10 Questions to Ask a Window Replacement Contractor

> 10 questions to ask a window replacement contractor — U-factor, installation method, flashing details, and warranty terms that determine performance.

![10 Questions to Ask a Window Replacement Contractor](/images/windows/shutterstock_274752782.jpg)

Reviewed by the Remodel Your Home editorial team · Updated August 19, 2026

Window replacement involves product selection, rough opening prep, flashing, sealing, and interior finishing. The cheapest bid often skips flashing details or installs a lower-tier glass package than quoted. These questions close those gaps.

## The 10 Questions — and Why Each One Matters

A contractor who answers these confidently, with specifics, is demonstrating the transparency and competence that separates good work from mediocre work.

1

### “Are these windows Energy Star certified, and what are the U-factor and SHGC ratings?”

**Why this matters:** U-factor measures heat transfer (lower = better insulation). SHGC measures solar heat gain (lower = less heat in summer, higher = more passive solar in winter). Energy Star minimums vary by climate zone — ask for the specific values for the window being quoted, not just "Energy Star certified."

2

### “What is the frame material, and what are its maintenance requirements?”

**Why this matters:** Vinyl requires no maintenance but can't be painted. Fiberglass is more dimensionally stable and can be painted. Wood-clad offers aesthetics but requires periodic exterior maintenance. Each has different thermal performance. Make sure you know what you're getting.

3

### “Do you manufacture your own windows, or are these a third-party brand — and which product line?”

**Why this matters:** Many installers sell proprietary window lines with limited external reviews. Ask for the brand name, series, and model. Research it independently. Manufacturer warranties vary significantly — 10-year vs. lifetime, transferable vs. non-transferable.

4

### “How do you handle discovery of rotted framing or damaged rough openings?”

**Why this matters:** Rot in the rough opening framing is common, especially in older homes. Ask what happens when they find it: fixed price per LF of framing replacement, or hourly? Get this in writing before demo begins.

5

### “What does your installation warranty cover, and for how long?”

**Why this matters:** Product warranties cover glass and hardware defects. Installation warranties cover the contractor's workmanship — flashing, sealing, trim finishing. These are separate. Ask: if water infiltrates around the frame in year 3, is that a product claim or an installation warranty claim, and who handles it?

6

### “Are you pulling permits for this installation, and are you a licensed contractor in my state?”

**Why this matters:** Window replacement usually needs a permit, especially where structural changes are involved — confirm with your local building department. Permits mean inspections — a safeguard for you.

7

### “How many windows can your crew complete in a typical day?”

**Why this matters:** Rushing a window installation leads to flashing shortcuts. A professional crew should complete 6–10 standard windows per day. Very high numbers (15–20/day) suggest minimal attention to flashing and sealing detail.

8

### “What is your process for protecting interior finishes — floors, walls, trim — during installation?”

**Why this matters:** Window installation creates dust, requires temporary weather exposure, and sometimes damages interior trim. Ask specifically: do they use floor protection, how do they handle interior trim removal and replacement, and who patches drywall?

9

### “Do you offer financing, and what are the terms including APR?”

**Why this matters:** Many window companies offer 0% financing for 12–18 months. After the promotional period, rates often jump to 25–29%. Know the full terms before using contractor financing.

10

### “Are you a certified installer for the window brand you're selling?”

**Why this matters:** Manufacturers like Renewal by Andersen require certified installers for warranty validity. Ask to see the certification for the specific brand. An uncertified installer may void the manufacturer warranty.

## Red Flags to Watch For

Any of these during your contractor search should prompt closer scrutiny or disqualification:

- Same-day pricing pressure with a deadline
- Won't provide U-factor/SHGC in writing
- Offers to skip permits to "save you money"
- Vague about who specifically will do the installation
- No written warranty terms — "we guarantee our work" verbally only
- Significantly lower bid without explanation of what's different

## Related Guides

- [Window Replacement Cost Guide — what to budget](/window-replacement-cost/index.md)
- [Best Window Replacement companies — how we rate contractors](/best-window-replacement-companies/index.md)
- [Signs it’s time to replace, not repair](/window-replacement-signs/index.md)

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Source: https://remodelyourhome.com/window-replacement-questions/