A cheaper window quotation is only cheaper when it includes the same windows, evidence, accessories and delivery responsibilities.

Three totals sit in the tender sheet. The lowest is highlighted green. Two pages later, that supplier has excluded screens, subframes and special packing; another has changed the glass; the third priced an older schedule. Before ranking prices, rebuild the comparison around scope.

Lock one comparison baseline

Issue the same drawing revision, schedule and clarification log to every bidder. Record the return date and do not silently combine answers from different revisions.

If a late addendum arrives, ask every supplier to show the delta rather than replacing the earlier quote without explanation.

Normalize the technical offer

Create one line for each window mark and compare system, dimensions, opening, glass, finish, hardware and quantity. Flag substitutions rather than hiding them inside a note.

A substitution may be sensible, but it needs a technical and commercial decision—not automatic acceptance because it lowered the total.

  • Profile and thermal break
  • Glass and spacer
  • Finish and colour
  • Hardware and screens
  • Performance evidence
  • Unit quantity

Put every exclusion in the price table

Separate subframes, trims, flashings, sealants, fixings, accessories, spares, samples, testing, packing, freight, unloading and installation support.

Use three states: included, excluded, or allowance. A blank cell is not an answer.

Compare risk that has not been priced

Note unverified sizes, missing structural review, unapproved colours, evidence gaps and provisional shipping assumptions. These are not always reasons to reject a bid, but they are reasons not to treat the total as fixed.

Assign each open item an owner and closure date. The comparison becomes much more useful when uncertainty is visible.

Write the award basis in one page

Summarise the selected scope, accepted deviations, remaining conditions and documents that form the order. Attach the final comparison and clarification log.

Months later, this page should explain why the chosen offer was commercially complete—even if it was not the lowest first number.

Use a comparison sheet with evidence beside the price

Give each supplier its own response column, but keep one common requirement column. For each line, record the quoted amount, inclusion status, supporting document revision and unresolved question. An unpriced item should stay unresolved rather than become zero in the spreadsheet.

  • Product baseline: mark, quantity, dimensions, opening, profile, glass, finish and hardware.
  • Supplied accessories: screens, trims, subframes, fixings, spares and their exact quantities.
  • Evidence and approvals: samples, drawings, inspection scope and any separately priced testing.
  • Delivery scope: packing, freight, named delivery location, unloading and site handling responsibilities.
  • Commercial basis: currency, quote validity, payment schedule and the assumptions behind any allowance.

A lower headline price can reverse after scope alignment

Consider a simplified example in one comparison currency, not a Cavorlen quotation or market price. Offer A is 10,000 and excludes screens priced at 800 and packing priced at 400. Offer B is 10,700 and includes both. If product configurations and all remaining scope are equivalent, A becomes 11,200 for those three lines, so B is lower by 500.

This calculation is useful only because the omitted amounts are known. If A has not priced packing, record an open clarification or a clearly labelled provisional estimate; do not describe 11,200 as a firm supplier total. If the two offers use different glass, resolve that difference before treating them as comparable.

Keep freight, import charges and site costs outside this simplified example until their scope and basis are confirmed. ICC explains that Incoterms rules clarify delivery tasks, costs and risks; a three-letter term alone does not make two offers identical. Record the named location and agreed version, and obtain route-specific cost inputs from the responsible parties.

Send a clarification request that can be closed

Use a short, numbered request: identify the quotation and schedule revision; list each mismatch by opening mark; ask the supplier to confirm inclusion or provide a separate price; request the revised total and validity; then record whether the response changes lead time or the proposed configuration. Keep the original offer so the adjustment remains traceable.

For a comparable project quotation, provide the opening schedule, drawings, intended destination and unresolved requirements. Use the specification checklist to prepare the technical baseline before requesting a revised offer. Explore: Window specification checklist; Request a project quotation.

FAQ

Can quotations in different currencies be compared directly?

Only after using a dated exchange-rate basis and aligning freight, tax, duty, payment terms and validity.

How should optional items be handled?

Keep options outside the base comparison and show their technical impact and price separately.

What is the most common hidden omission?

It varies, but screens, subframes, trims, packing, testing and site-related scope frequently create later differences.

Continue the project review

Connect this guide with the proposed window and door systems, then review how Cavorlen approaches manufacturing and quality control. When your schedule is ready, send it through the project review form.

Official sources used

Incoterms® rules — ICC ↗FGIA — technical resources ↗

Related buyer guides

Editorial boundary

This buyer guide provides a review method, not project-specific engineering, legal or compliance approval. Confirm the governing specification, applicable requirements and authorised project decisions before acting.