How to Compare Window Quotations

Before comparing prices, check whether each quotation is actually pricing the same thing. It is entirely possible for three quotations described as 'aluminium windows' to specify three different profile systems, glass builds and levels of finish.

• Profile system named specifically, not just 'aluminium'
• Glass specification stated, including U-value and any solar control or acoustic glass
• Hardware brand and finish specified, not just 'chrome handles'
• Colour and finish, inside and out if they differ
• Trickle vents, restrictors or other regulatory items included or excluded

A significantly lower quotation is not automatically a red flag, but it is worth understanding why the figure is lower before assuming it is simply better value. Common reasons include a lighter-grade profile system, standard rather than upgraded glass, exclusion of disposal or making-good, or a shorter guarantee.

Missing items do not disappear from the project. Scaffolding, specialist lifting, disposal, lintel work, drainage, plaster or render repairs, decoration and Building Control fees may simply arrive through another trade. Add a realistic allowance for every necessary omission before comparing the completed-project totals. A lower quotation remains the better choice when the named specification and scope are genuinely equivalent and the difference reflects efficiency rather than missing work.

Price is one axis of comparison; programme and process are others that matter just as much for a project you will live through. Ask each supplier how long from order to installation, how a survey is conducted, how installation is sequenced, and what handover and aftercare actually involve — see our guides on what happens during a survey and what to expect during installation for what good process looks like.

1. 01Request a like-for-like re-quoteAsk each supplier to quote against the same written specification so the numbers are directly comparable.
2. 02Check what is excludedAsk explicitly what is not included — access equipment, disposal, decoration, structural remedial work.
3. 03Compare guarantees in writingRead the guarantee terms rather than relying on a verbal summary of 'ten years' or similar.
4. 04Ask for the process, not just the priceA clear description of survey, manufacture and installation steps is itself a useful quality signal.

A quotation tells you the price; the answers to these questions tell you what you are actually buying. Ask each company the same set, and compare the answers alongside the figures.

• Which system do you supply, and who manufactures it? A named system you can research is a different proposition from an unnamed profile.
• Do you fabricate in-house or buy in finished frames? Both are legitimate, but it changes who is accountable if something needs remaking.
• What U-value does the quoted specification achieve as a whole window, not just the glass?
• Who carries out the installation — your own teams, or subcontractors you use regularly?
• Is the survey carried out before manufacture, and does the price change after it?
• What is the lead time from confirmed order to installation, and what happens if it slips?
• What exactly does the guarantee cover — frames, finish, glass units, hardware, installation — and for how long each?
• Is the finish a polyester powder coat, and does it carry a written finish warranty?
• What is excluded: scaffolding, disposal, making good, decoration, structural work?
• Which Building Regulations certification route applies, who is responsible for it, and what document will I receive?
• Can I see completed projects of a comparable size and specification?
• What is the payment schedule, and what deposit is required to start manufacture?

The quality of the answers matters more than the answers themselves. A company that answers precisely, without hedging, and volunteers the exclusions before you ask is usually the one whose quotation will still be accurate at the end of the job.

Compare two glazing quotations line by line, not by the bottom-line figure. Set them side by side and check that each one describes the same frame system, the same glass build-up, the same sizes and opening configurations, the same colours and hardware, and the same scope of work — removal, disposal, making good, certification and delivery. Where a line is missing from one quotation, price it in before comparing totals. In most cases the price gap between two honest quotations is explained entirely by the lines below.

Once every line is present on both quotations, price the gaps. A quotation that excludes disposal, access equipment and making good is not cheaper than one that includes them; it is simply a smaller quotation. Adding a realistic allowance for each missing line usually closes most of the difference, and what remains is a genuine specification or service difference you can then judge on its merits.

• If specifications differ, normalise them before comparing price at all
• If a quotation excludes disposal or making-good, add a realistic allowance before comparing totals
• If lead times differ significantly, weigh that against your own programme constraints
• If guarantee terms differ, treat shorter or narrower cover as a real cost, not a minor detail
• If a supplier cannot explain their own specification clearly, treat that as more telling than the price itself

• Comparing headline totals without checking scope of works is identical
• Assuming 'aluminium' means the same product across every quotation
• Ignoring guarantee terms until after the contract is signed
• Treating an estimate-based quotation as a fixed price before survey
• Choosing on price alone without asking about installation process and aftercare