15 Questions to Ask Your Window Contractor Before Signing

Most homeowners get multiple quotes for window replacement but ask the same basic questions at each: "How much?" and "How long?" The questions that actually reveal contractor quality are about permits, product specifications, installation method, and what happens when something goes wrong.

Permit and Compliance Questions

1. Will you pull the permit for this project?

A licensed contractor should be able to — and typically should — pull permits on your behalf. If a contractor says "permits aren't needed" for work that clearly requires one (egress window, size change, new opening), that is a red flag. Verify their answer against what the building department tells you.

2. What is the permit fee and is it included in your quote?

Some contractors include permit fees; others add them separately. Know before you sign. A contractor who can't tell you the permit fee hasn't verified whether a permit is required.

3. Are you familiar with the current energy code for our area?

Ask them what U-factor and SHGC the windows they are quoting meet, and whether that satisfies your local IECC climate zone requirement. If they don't know their IECC climate zone, that is a significant concern.

Product Specification Questions

4. What is the NFRC whole-window U-factor and SHGC of the windows you are quoting?

Ask them to show you the NFRC label or product specification sheet. "Energy efficient" is a marketing term; U-factor and SHGC are the actual performance metrics. Compare them against your climate zone requirements.

5. What is the warranty on the window unit and on the installation labor?

Quality window manufacturers offer lifetime warranties on hardware and 20-year warranties on glass seal failure. Contractor labor warranties typically range from 1–5 years. Get both in writing.

6. What frame material and glass package are you specifying?

Vinyl vs. fiberglass vs. wood-clad have very different long-term performance and cost characteristics. Single low-E vs. double silver low-E with argon affects both U-factor and cost. Make sure you are comparing equivalent products across quotes.

7. In Florida: what is the Florida Product Approval (FPA) number for these windows?

Every window installed in Florida requires a valid FPA number. If the contractor cannot provide it, the product has not been approved for Florida installation. In Miami-Dade/Broward, ask for the NOA (Notice of Acceptance) number.

Installation Method Questions

8. How do you handle sill pan flashing?

A quality contractor should be able to describe their specific flashing method: whether they use a sill pan, how they integrate it with the building wrap, and how they handle the head flashing. "We follow the manufacturer's installation instructions" is a reasonable answer — ask what those instructions specify.

9. What do you do with the gap between the window frame and rough opening?

The correct answer is: fill with low-expansion foam (not high-expansion, which can bow the frame), then cover with backer rod and caulk at the exterior. Contractors who say "we just caulk it" are skipping the foam insulation step that prevents air infiltration and freeze-thaw cracking.

10. Will you replace any deteriorated trim or flashing discovered during installation?

Sometimes removing old windows reveals rotted sills, damaged sheathing, or failed flashing that must be repaired before the new window is installed. Clarify upfront whether this is included or billed separately, and at what rate.

Project Management Questions

11. How long from contract signing to installation?

Custom or special-order windows have lead times of 6–14 weeks. Stock windows can be installed within 1–2 weeks. Know whether you are ordering custom or stock, and what the lead time is — it affects your project timeline significantly.

12. Who are your workers? Are they your employees or subcontractors?

General contractors who subcontract installation should be able to name the subcontractor and confirm they are licensed and insured. Ask to see insurance certificates for both the general contractor and any subcontractor who will be on your property.

13. How do you handle permit inspections?

The contractor should schedule and be present for required inspections. Ask: "Do you coordinate inspection scheduling, or is that on me?" and "What do you do if the window fails inspection?"

Post-Installation Questions

14. What is your process if there is a problem after installation?

Ask specifically: "If I notice a draft or water infiltration within the first year, what happens?" A confident, reputable contractor answers this question clearly. Evasive answers or immediate referral to the manufacturer warranty are warning signs.

15. Can you provide references from window projects in this area within the last 12 months?

Ask for 2–3 references from similar projects. Call them. Ask specifically: "Did they handle the permit? Did it pass inspection the first time? Was there any water infiltration after installation, and if so, how was it handled?"

Red Flags That Should Give You Pause

• Cannot tell you the NFRC U-factor of the windows they are quoting
• Says permits are never needed (without having called the building department)
• Significantly lower price than all other quotes with no explanation
• Cannot provide proof of contractor's license and general liability insurance
• Asks for more than 30–40% deposit upfront
• Unwilling to provide references from recent comparable projects
• In Florida: cannot provide Florida Product Approval number for the windows