The Cheapest Window Quote Is Not Always the Cheapest Project

Do not assume the phrase ‘fully fitted’ resolves every boundary. Ask what happens to plaster, render, stone, cills, decoration, alarms, blinds and damaged substrate after the old frame is removed.

Two drawings can show the same openings while the quotations specify materially different projects. One may use a named thermally broken aluminium system and project-specific glass; another may use a different profile, standard glass, basic hardware or a threshold unsuited to the desired floor detail. Those differences are not automatically good or bad, but they must be visible.

• Frame system, reinforcement and opening limits
• Glass build-up, safety treatment, coatings and acoustic or solar-control requirements
• Hardware grade, colour and restrictors
• Weathered, low or flush thresholds and associated drainage
• Internal and external colour and finish
• Cills, trims, flashings and perimeter sealants

An exclusion is not a defect if it is deliberate and priced elsewhere. It becomes expensive when no one has allowed for it or when two trades each assume the other is responsible.

Suppose one quotation excludes scaffolding, disposal and internal making good, while another includes all three. The first number is smaller, but the homeowner still needs those tasks completed. Once realistic allowances are added, the order may reverse. The same applies where a low threshold requires drainage work, large glass requires mechanical lifting, or a rough opening changes after technical survey.

Performance suitability also has a cost dimension. A product selected without regard to opening size, exposure or drainage may require redesign before order, or remedial work later. That does not mean the expensive system is always superior; it means suitability should be established before price is treated as final.

Choose the lower quotation with confidence when the named frame and glass specification are equivalent, the installation and finishing scope match, exclusions and provisional sums are equally clear, payment terms are acceptable, certification and written warranty routes are comparable, and the installer can show relevant competence.

1. 01Fix the required specificationName the system, glass, openings, colours, hardware and thresholds.
2. 02Mark every blank lineTreat an unmentioned item as unknown, not included.
3. 03Price necessary exclusionsObtain realistic allowances from the responsible trade.
4. 04Separate upgradesRemove optional enhancements if they are not part of the common brief.
5. 05Compare the completed outcomeUse the adjusted total, process, warranties and evidence together.

A supplier should be able to explain a price difference without predicting failure or disparaging another company. Ask for the technical or scope reason. If the difference cannot be identified in the written specification, it should not carry much weight in the decision.

Compare the deposit, staged payments and balance trigger alongside the total. A low figure with a large early payment transfers more risk than the same figure with payments tied to clear milestones. Check what confirms the manufacturing slot, what happens if building work delays installation and whether storage or repeat delivery can become chargeable.

Programme has a project cost too. If late glazing delays plastering, finishes or occupation, the consequence may be larger than a modest difference between quotations. That is not a reason to accept an unrealistic promise. Ask for a realistic range, the point from which lead time runs and which customer decisions must be complete before the clock starts.

Water around a threshold, cracked finishes or a door that will not run correctly can involve product, installation, structure, levels or surrounding building work. A complete quotation and survey reduce ambiguity by recording the intended interfaces and responsibility boundaries. They do not eliminate every future issue, but they make diagnosis and resolution more direct.

Do not add an arbitrary future-repair allowance to every lower quotation. Instead, compare evidence that foreseeable risks have been considered: suitable system limits, final dimensions, drainage, access, installation method and a clear aftercare route.

Quotation A is lower and excludes access equipment, disposal and internal plaster repairs. Quotation B includes those items but specifies the same frame, glass and hardware. The fair comparison is not A against B as printed. Add genuine prices for the three missing scopes to A, then compare the adjusted totals, payment terms and delivery responsibilities.

If A remains lower and the installer, survey, certification route and warranty are comparable, A may be the better deal. If B becomes lower once the gaps are filled, its original headline was not expensive; it was more complete. The method protects both lower-priced and more comprehensive quotations from an unfair comparison.