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Window Replacement: 9 Questions That Cut Through the Sales Pitch

Window replacement is a high-margin industry with aggressive sales tactics, confusing energy ratings, and widely varying installation quality. The window itself matters less than how it's installed -- an expensive triple-pane window installed with poor flashing and minimal insulation around the frame will underperform a mid-range window installed correctly. Bring this checklist to your consultation and you'll cut through the sales pitch in minutes.

9 QuestionsPrintable ChecklistAvg Cost: $300 - $1,200 per window

Questions to Ask

1Are you recommending a full-frame replacement or an insert (retrofit) window, and why?

Why It Matters

Full-frame replacement removes the entire window including the frame, allowing inspection and repair of the rough opening. Inserts fit inside the existing frame, which is faster and cheaper but reduces glass area and hides potential rot.

Red Flag

They recommend inserts for every situation without inspecting the existing frames, or they push full-frame when the existing frames are in good condition.

Pro Tip

Inserts work well when existing frames are solid, square, and undamaged. If there are signs of rot, water damage, or out-of-square frames, full-frame replacement is worth the additional cost.

2What is the U-factor, SHGC, and VT rating of the windows you're recommending?

Why It Matters

U-factor measures heat transfer (lower is better). SHGC (Solar Heat Gain Coefficient) measures how much solar heat passes through (lower is better in hot climates, higher in cold). VT (Visible Transmittance) measures light transmission.

Red Flag

They can't explain these ratings, or they recommend the same glass package regardless of your climate and window orientation.

Pro Tip

In hot Southern climates, prioritize low SHGC (below 0.25). In cold Northern climates, moderate SHGC (0.30-0.40) on south-facing windows captures free solar heat. The ENERGY STAR program has climate-specific recommendations.

3How will you flash and waterproof the window opening during installation?

Why It Matters

Improper flashing is the number one cause of water damage around windows. Sill pan flashing, properly lapped membrane, and integration with the house wrap prevent water from entering the wall cavity.

Red Flag

They rely only on caulk for waterproofing, or they don't mention flashing at all.

Pro Tip

Best practice includes: a sill pan (either formed or membrane), peel-and-stick membrane on the sill and jambs, and integration with the existing house wrap using a shingle-lap technique. Caulk is supplemental, not primary waterproofing.

4Will you insulate around the window frame after installation?

Why It Matters

Gaps between the window frame and rough opening are a major source of air infiltration and energy loss. These gaps must be insulated, but the wrong insulation can bow the frame and prevent proper operation.

Red Flag

They use expanding foam that could bow the frame, or they leave gaps uninsulated.

Pro Tip

Low-expansion foam or backer rod with caulk is appropriate for the gaps around window frames. Standard expanding foam exerts too much pressure and can bow the frame, making windows hard to open.

5What window brand and product line are you installing, and what are the warranty terms?

Why It Matters

Window quality varies enormously within a single brand. A manufacturer's builder-grade line is significantly different from their premium line, even though both carry the same brand name.

Red Flag

They won't specify the exact product line, or they use a brand with limited warranty coverage or poor reviews.

Pro Tip

Ask for the specific series or product line name. Research it independently. Look for: lifetime frame warranty, 20+ year glass seal warranty, and a manufacturer reputation for honoring warranty claims.

6What happens if a glass seal fails and the window fogs?

Why It Matters

Double and triple-pane windows have sealed gas fills (argon or krypton). When the seal fails, moisture condenses between panes, creating permanent fogging. This is a defect, not normal wear.

Red Flag

They say fog is normal or that you'll need to buy a whole new window if a seal fails.

Pro Tip

The glass seal should be warrantied for at least 20 years by the manufacturer. When a seal fails under warranty, the manufacturer should provide a replacement insulated glass unit at no cost.

7How will you handle the interior trim and exterior capping after installation?

Why It Matters

Interior trim (casing) and exterior capping (cladding over exposed wood) complete the installation visually and protect against water and air infiltration. Poor trim work makes an expensive window job look cheap.

Red Flag

Interior trim is not included in the bid, or they plan to caulk over exposed wood instead of capping it with aluminum or PVC.

Pro Tip

Exterior wood should be capped with aluminum or PVC coil stock that is cut and bent on site to fit. Interior trim should match existing woodwork or be a clean, finished replacement.

8Will you remove and dispose of the old windows, and is there any lead paint concern?

Why It Matters

In homes built before 1978, window removal can disturb lead paint. The EPA requires RRP (Renovation, Repair, and Painting) certification for any contractor disturbing lead paint in pre-1978 homes.

Red Flag

They plan to remove old windows from a pre-1978 home without EPA RRP certification or lead-safe work practices.

Pro Tip

Ask for their EPA RRP firm certification number if your home was built before 1978. Old window removal and disposal should be included in the bid.

9Can I see completed installations before and after, and speak to recent customers?

Why It Matters

Window installation quality is hard to assess from a showroom. Photos and references from completed jobs show trim detail, flashing approach, and customer satisfaction.

Red Flag

They have no project photos or references available.

Pro Tip

Ask specifically about installations in homes similar to yours (same style, age, and window type). Ask references: Were windows installed on time? Any water issues? How was the cleanup?

Bonus Tips for Hiring a Window Contractor

  • Never let a window salesperson pressure you into signing the same day for a 'today only' discount. This is the most common high-pressure tactic in the window industry.
  • Get at least three bids that specify the exact window brand, product line, installation method (full-frame vs. insert), and what's included (trim, capping, disposal, permits).
  • Check for available energy efficiency tax credits and utility rebates. ENERGY STAR certified windows may qualify for federal tax credits, and some utilities offer additional rebates.
  • If only some windows need replacement, prioritize: windows with failed seals (fogged), windows that don't open/close properly, and windows on the side of the house with the most sun or wind exposure.

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