An estimate is an informed indication of likely cost; a quotation is normally a more definite offer for stated work. Whichever label is used, unclear scope creates disputes, so the document should explain exactly what has and has not been priced.
This guide is written for Scottish trade readers. Check the current position against GOV.UK invoicing guidance, Small Business Commissioner contract guide and Citizens Advice building-work guidance; project and business circumstances can change the answer.
Name the document accurately
Use an estimate when important quantities or conditions remain uncertain. Use a quote only when the survey, product and work are sufficiently defined, and state how long it remains open. For related practical context, see trade casement windows.
Describe scope opening by opening
List the unit references, products, glazing, finish, removal, disposal, making good and access provision. Attach drawings or schedules where they form part of the offer. The existing guide to pricing window fitting work helps connect the decision to job costing.
State assumptions and exclusions
Identify concealed defects, asbestos, structural work, decorations, permits, parking and customer-supplied information. Exclusions should be visible, not hidden in small print. It is also worth reviewing setting up a window trade account before committing to recurring supply.
Control variations in writing
When conditions or customer choices change, describe the effect on price and programme and obtain agreement before extra work proceeds.
Working checklist
| Document element | What to include | Why |
|---|---|---|
| Scope | Units, product and work included | Creates a shared baseline |
| Price basis | Fixed quote or estimated allowance | Sets expectations |
| Programme | Dependencies and indicative dates | Avoids unsupported promises |
| Payment | Deposits, stages and due dates | Supports cash flow |
| Variations | Written approval process | Controls changes |
Next step
Confirm the project facts in writing before relying on a general guide. Trade Windows Scotland supplies made-to-measure windows to trade customers; the related Clyde Windows uPVC window service provides additional affiliated service context.
This article provides general business information, not tax, accounting or legal advice. Check current official guidance and obtain advice for your circumstances.
Use the right document for the level of certainty
An estimate is useful before intrusive survey, final product selection or confirmation of access because it signals that the price may change. State the assumptions, likely range and what must happen before a firm offer is issued. A quotation should define the work and price precisely enough for acceptance to form a contract; calling a document ‘budget only’ will not cure detailed language that otherwise looks like a firm promise.
Include an expiry date and explain that manufacture starts only after the agreed survey, specification, deposit and written approval. If raw-material pricing or grant approval is uncertain, set out how that risk is handled. Consumer communications must remain clear and fair, so avoid vague clauses allowing any price increase for any reason.
Describe the job opening by opening
Use unique references and attach an elevation or schedule showing size basis, style, handing, glazing, colour, cills, vents, hardware and accessories. State whether removal, disposal, internal and external making good, trims, scaffolding, permits, parking and decoration are included. Identify work by others, such as asbestos handling, alarms, blinds, structural repairs or electrical relocation.
Record site assumptions: sound substrate, clear access, working hours, power, welfare, parking and safe storage. For tenements and occupied homes, note protection, stair access and resident coordination. The more closely the price maps to the survey, the easier it is for the fitter, customer and accounts team to recognise a genuine change.
Price uncertainty explicitly
Use provisional sums or clearly identified optional items only where the quantity or choice genuinely cannot be fixed. Explain how the final figure will be calculated and obtain approval before incurring the cost. Do not hide foreseeable items in small print and then present them as extras after the old frame is removed.
For concealed defects, state the observable basis of the price and the process if rotten structure, failed lintels or hazardous material is discovered. Stop, photograph, explain the implication and issue a written variation. Include labour, materials, programme and VAT effects, then obtain the required authority before continuing unless immediate safety work is necessary.
- Reason for the change
- Revised scope and opening reference
- Added or reduced price
- Programme effect
- Customer or contractor approval
Turn acceptance into a controlled handover
Make acceptance unambiguous: signed document, approved electronic acceptance or purchase order that refers to the quote revision. Confirm payment stages, cancellation terms, lead-time basis, warranty scope and who has authority to instruct changes. For consumer work, provide the required pre-contract and cancellation information for the way the contract is made.
Issue the approved schedule to purchasing and fitting, then compare the supplier acknowledgement against it. At completion, record snags and distinguish them from new work. Invoice using the same job and purchase-order references. A strong quote is not just a sales document; it is the control sheet for ordering, installation, variation and payment.