# Choose guides

> How to choose a contractor: independent, numbers-first guidance from Window Replacement Lab.

Canonical: https://windowreplacementlab.com/reviews/

Last updated: 2026-11-08

## How to vet a window installer

This is a high-ticket, high-pressure sale. The difference between a good installer and a bad one is in the diagnosis, the scope and the warranty — not the demonstration or the truck.

 |  | Criterion | Weight | What good looks like

 | Diagnosis | 30% | Frame and flashing inspected before a scope is written

 | Written scope | 25% | Unit model, labour per opening, removal, flashing, trim, permit

 | Warranty | 20% | Written, transferable, and it names what voids it

 | Track record | 15% | Jobs you can visit; licence and insurance on file

 | Price transparency | 10% | Unit pricing, no expiring discount

## Red flags specific to windows

- A price that is only valid if you sign during the visit.

- A "buy one get one" or per-window discount that moves with the sales pressure.

- No U-factor or SHGC number on the quote — if the glass rating is not stated, the unit is not specified.

- No mention of flashing at all. Flashing is where window leaks begin.

- A warranty document you are not given at signing.

- Financing presented as a discount rather than a loan with a rate and a term.

- A quote that prices "windows" as one number instead of a unit line and a labour line.

## Questions that separate the good from the rest

- What did you inspect, and did you check the sill and the flashing?

- Is this an insert or a full-frame scope, and why that one here?

- Which unit brand and model, and what is its U-factor?

- What exactly is included in removal, disposal and trim?

- Who pulls the permit, and is it in this price?

- What voids the warranty, and is it transferable to a buyer?

- Can I speak to a customer whose job is three years old?

## What the contract should contain

- The unit specification, not just a brand.

- Per-opening labour, and the number of openings.

- Removal, disposal and any dumpster fee.

- Flashing, insulation and sealant detail.

- Interior and exterior trim allowance, with a number.

- Permit responsibility and cost.

- Start date, duration and the payment schedule.

- Warranty terms, and the cancellation right your state gives you.

The [cost hub](/cost/) explains what each line should cost, the [comparison hub](/compare/) covers the method decision, and the [calculator](/calculator/) shows the component arithmetic.

### How many quotes should I get?

Three, against the same written scope. Three quotes for three different diagnoses are not comparable, and that is how the highest bidder wins by default.

### What licence is required?

It varies by state. Some require a general contractor licence, some a specialty window licence, some only registration. Ask for the number, check it against the state database, and confirm the name on the contract matches.

### Is a lifetime warranty worth paying for?

Only if it is transferable and the company will still exist in ten years. Read what voids it — most void on improper installation, which puts the liability back on the installer you also hired.