Get quotes that describe the same job
The most common mistake homeowners make is comparing quotes that describe different work. One contractor prices a retrofit installation of a basic vinyl slider; another prices a full-frame installation of a triple-pane casement. Of course the numbers differ — they are not the same job.
Before requesting quotes, decide on the scope: how many windows, which openings, and whether you want retrofit or full-frame installation. Write it down in a one-page brief and give the same brief to every contractor. When every quote answers the same brief, the differences that remain are meaningful.
What a complete quote should itemise
A quote you can compare line by line should list each window by location (for example, ‘master bedroom, north wall’), the window style and size, the frame material, the glass specification, and the installation method. It should separate product cost from labour, and state how disposal of old windows is handled.
Watch for lump-sum quotes with no breakdown. A single number for ’10 windows, installed’ tells you nothing about what is actually being supplied. Ask the contractor to break it down before you compare it with anything else.
Questions that expose the gaps
Ask every contractor the same questions: Who manufactures the windows, and what is the exact model? What glass specification is included? Is the installation retrofit or full-frame? How are the frames air-sealed and insulated? What is covered by the product warranty versus the installation warranty, and for how long? What happens if rot is found when the old window comes out?
The answers matter more than the price. Two quotes within a few hundred dollars of each other can describe very different levels of protection.
Read the terms before the total
Check the payment schedule, the start-date commitment, and what counts as an extra. Confirm who is responsible for interior trim repair and exterior capping, and get the warranty terms in writing rather than as a verbal promise.
Take your time. A reputable company will leave a written quote with you for days or weeks without pressure. If a quote expires in 48 hours, treat the urgency as information about the company, not about the price.