How to choose an installer

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 explains what each line should cost, the comparison hub covers the method decision, and the 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.