Comparing three double glazing quotes without losing your mind

Put all three onto one sheet

Before comparing totals, rewrite each quote into the same rows: profile and chamber count, glass spec, colour, opener count, locks, trickle vents, disposal, making good, certificate, guarantee length, deposit and balance timing. Any quote that can't fill in a row hasn't told you enough.

Doing this by hand takes ten minutes and immediately shows up the gaps. It's usually the cheapest looking quote that has the most blank rows once you actually try to fill the sheet in.

Discount pressure tactics

Watch for a price that only holds 'if you sign today', a huge crossed out original figure next to a suspiciously round discounted one, or a second visit where the price mysteriously drops further. Genuine pricing doesn't need theatre to justify itself.

If the same product is quoted twice at different figures within the same week with no change to the spec, that tells you the first number was never really the price, it was an opening position.

Deposit sizes

A deposit against a made to measure order is normal, but the size varies a lot between companies. Ask what percentage is asked for up front, what it covers, and what happens to it if the company can't complete the job.

Finance offers

Interest free finance can be genuinely free, or it can be a higher headline price with the interest built in and then 'waived'. Ask for the cash price and the finance price separately and compare the two before assuming finance is the cheaper route.

Timed offers

'This price is only available this week' on a bespoke made to measure product is worth treating with scepticism. A fair price for your job shouldn't depend on the calendar or on you deciding in the room.

What to ask each installer

Ask who actually fits the job, whether it's an employed team or subcontracted; how the deposit is protected; what the guarantee covers and for how long; and how the price would change if the survey finds something unexpected, like rotten timber behind an old frame.

• Who fits the job, employed or subcontracted?
• Is the deposit protected, and how?
• What does the guarantee cover, and for how long?
• Is the price fixed once surveyed, or can it move?
• What happens if something is found on survey day?

Reading between the lines on price alone

Two quotes for the same rough total can still be very different offers once the sheet is filled in, one might include a slimmer profile and no reinforcement, the other a thicker chamber count and steel where it's needed. Price only becomes useful for comparison once the spec either side of it is equal.

It also pays to check whether each quote covers exactly the same list of openings and the same extras, like new window boards or additional trickle vents, since a quote that quietly leaves one window off the list will naturally look cheaper than one that includes everything you actually want done.

Finally, keep a note of how each salesperson answered your questions rather than just the numbers they gave, since a company that answers plainly and in writing is usually easier to deal with later than one that was vague from the first visit.

Checking who you're actually dealing with

Before signing anything, it's worth checking how long the company has traded under its current name and whether the address and phone number given match what's on their paperwork and website. This takes a few minutes and is a reasonable thing to do for any bespoke, made to measure purchase, regardless of how the visit went.

It's also fair to ask directly whether the person quoting you is the person who will answer the phone if there's a problem after fitting, or whether you'll be passed to a separate customer service line. Neither answer is automatically wrong, but knowing which one you're getting avoids a surprise later.

When quotes cover different extras

Not every quote for 'the same job' actually includes the same list of extras. One installer might quietly include new window boards, disposal of an old conservatory roof panel, or an extra trickle vent that Building Regulations require, while another leaves these as separate add on costs. Read the small print for what's excluded, not just what's included, since exclusions are often where the real difference in final cost appears.