How to Compare Unitized Curtain Wall Quotations on the Same Scope
Why Unitized Curtain Wall Quotations Are Not Comparable by Total Alone
When two or more unitized curtain wall quotations arrive, placing the totals side by side is not yet a comparison. The suppliers may have used different drawing revisions, quantities, panel schedules, system configurations, delivery points, installation boundaries, alternatives, allowances, or commercial assumptions.
To compare unitized curtain wall quotations on the same scope, first freeze the common drawing, specification, revision, addenda, quantity, and panel-schedule basis. Then normalize system and material scope, engineering, testing, QA/QC, factory work, logistics, delivery, installation, and commercial terms. Record each difference and clarification before interpreting totals.
At the end of the process, classify the comparison with one of three labels:
- Comparable on stated basis: the material comparison basis is aligned or clearly qualified.
- Not yet comparable: material differences make a direct comparison misleading.
- Requires clarification: one or more open items could affect scope, responsibility, technical interpretation, commercial terms, or programme.
These labels describe whether you are ready to compare, not which supplier is better. A lower total is not automatically a better or more complete bid.
This is the final guide in our unitized curtain wall buying series. It assumes the RFQ has been issued and quotations have come back. For the earlier steps, see our guides on pricing factors, preparing an RFQ, and what a single quotation should include.
The Five-Stage Same-Scope Comparison Workflow
- Freeze the common basis. Confirm the documents, revisions, addenda, quantities, panel schedule, technical requirements, delivery basis, and commercial assumptions.
- Normalize scope and responsibility. Compare each bidder's response against the same system, materials, engineering, testing, factory, logistics, installation, and handover fields.
- Identify bid deltas. Record differences with an evidence reference, responsible party, potential effect, and status.
- Issue controlled clarifications. Ask material questions consistently and record responses, affected bidders, and changes.
- Classify comparability. Decide whether the comparison is Comparable on stated basis, Not yet comparable, or Requires clarification.
Your project and procurement documents govern the process that applies.
Within the comparison tables, each bidder's line items keep the five scope statuses used in single-quotation review: Included, Optional, Excluded, Subject to Confirmation, and Open Question. Working fields such as "Open/closed" or "Confirm/clarify" track progress; only the three labels above are final outcomes.
Stage 1: Freeze the Common Document, Revision, and Quantity Basis
Document and Specification Register
For each quotation, record the document title, number, revision, issue date, specification section, schedules, and model or file version used. Compare each bidder's stated basis against one common register.
Check whether the quotations use the same:
- General arrangement drawings, elevations, sections, and details
- Facade specifications and referenced product requirements
- Panel or module schedules
- Quantity take-offs and area measurement basis
- BIM or CAD model versions where applicable
- Addenda, bidder questions, and clarification responses
- Later corrections or reissued documents
A quotation based on a different revision is not automatically wrong, but it is not a same-basis comparison until the difference is understood. Record the changed document and the potentially affected scope rather than silently replacing one bidder's basis with another's.
Addenda and Clarification Responses
Record whether each bidder acknowledged the same addenda and responses. If material information was issued during the procurement process, follow your project's rules for distribution and amendment control.
Quantities, Panel Schedules, and Non-Unitized Areas
Compare whether each quotation uses the same:
- Facade area and measurement basis
- Building, elevation, floor-zone, and phase breakdown
- Panel count and module schedule
- Typical, repeated, mirrored, unique, and custom panels
- Corners, transitions, openings, fins, shading, and special interfaces
- Non-unitized areas and work by others
- Delivery batches and programme phases
- Allowances for design-development or unresolved areas
Do not infer the cause of a quantity difference from the total alone. Use the take-off, panel schedule, drawing reference, supplier qualification, or clarification response as evidence.
Common-basis freeze checklist:
| Basis field | Common baseline | Bidder A | Bidder B | Bidder C | Status/open issue |
|---|---|---|---|---|---|
| Drawing/specification register | Common issue list and revisions | Documents used | Documents used | Documents used | Confirm / clarify |
| Addenda and clarifications | Common amendments and responses | Acknowledged? | Acknowledged? | Acknowledged? | Confirm / clarify |
| Quantity basis | Facade area, panel count, phases | Stated basis | Stated basis | Stated basis | Confirm / clarify |
| Panel/module schedule | Common schedule and non-unitized areas | Used/deviation | Used/deviation | Used/deviation | Confirm / clarify |
| Technical basis | Common system, glass/infill, testing, and QA brief | Basis stated | Basis stated | Basis stated | Confirm / clarify |
| Scope boundary | Materials, engineering, factory, logistics, installation, handover | Stated basis | Stated basis | Stated basis | Confirm / clarify |
| Delivery basis | Named location, customs, unloading, storage, lifting | Stated basis | Stated basis | Stated basis | Confirm / clarify |
| Commercial basis | Currency, validity, tax/duty, payment, programme | Stated terms | Stated terms | Stated terms | Confirm / clarify |
Stage 2: Normalize Quotation Identity and Commercial Basis
Before comparing totals, confirm that each quotation represents the same type of commercial offer.
Quotation Identity and Validity
Record the issuing entity, project and package reference, quotation number, revision, issue date, validity, referenced documents, and clarification contact. Note whether the offer is supply-only, delivered-to-site, technical-support-only, design-assist, delegated-design, supply-and-installation, or another arrangement.
Currency, Taxes, Duties, and Payment
Compare the stated currency, tax and duty basis, insurance assumptions, payment terms, retention or bonds where applicable, and escalation provisions. If currencies or tax treatments differ, do not create a normalized price without documented project assumptions and commercial review.
Quantity and Commercial Structure
Identify whether each bid is a lump sum, unit-rate schedule, allowance, provisional item, base bid with alternatives, or a combination. Record unit-of-measure assumptions, alternates, allowances, provisional items, exclusions, qualifications, and open questions.
Delivery, Installation, and Programme Basis
Compare delivery point, port or inland route, unloading, storage, lifting, installation, supervision, handover, and programme dependencies. "Delivered" or "installed" are not equivalent labels unless the responsibility boundary is documented.
Stage 3: Normalize Scope, Technical Basis, and Responsibilities
Apply the five scope statuses to every bid. The purpose is not to decide which quotation has "more included," but whether each response addresses the same requirement and assigns responsibility consistently.
System, Materials, Glass, and Infill
Compare the stated system family or configuration, glazing method, glass plane, system depth, aluminum profiles, reinforcement, thermal breaks, gaskets, sealants, anchors, brackets, hardware, finishes, glass make-up, infill, openings, corners, transitions, non-unitized areas, and alternatives.
A shared product family name does not mean two configurations are equivalent. The screening fields on our Unitized Curtain Wall Systems page (glazing method, glass plane, system depth, infill, and performance categories) work well as comparison columns.
Engineering, Testing, and QA/QC
Compare whether each bid states:
- Design-assist or delegated-design boundary
- Calculations and analyses
- Shop and fabrication drawings
- BIM authoring, coordination, file exchange, and revisions
- Mockup specimen and test scope
- Test method, agency, witnessing, and report
- Retesting and corrective-work responsibility
- Factory inspection and release criteria
- Material and finish traceability
- Nonconformance and rework
- Handover records
When bids cite ASTM E2099-23 (pre-construction laboratory mockups) or ASTM E331-00(2023) (water-penetration testing), check that they refer to the same specimen, configuration, and responsibility. Citing the same standard does not make two bids technically equivalent.
Factory, Logistics, Delivery, Installation, and Handover
Compare the stated boundaries for:
- Factory assembly, factory glazing, sealing, inspection, labeling, storage, and release
- Packaging, loading, protection, shipping, insurance, and loss/damage responsibility
- Customs, duties, taxes, delivery point, unloading, storage, and lifting
- Hoist/crane, floor access, staging, and site-readiness assumptions
- Installation labor, supervision, training, technical support, site adjustments, and replacement
- Re-delivery, handover, maintenance documents, and work by others
Factory-glazed unitized panels, such as FOWALL's, move much of this scope into the factory, so confirm in each bid exactly which factory operations and release records are included.
Stage 4: Build a Bid Delta Register
A bid delta is a documented difference between the common baseline and a bidder's response. It is not automatically an error, an omission, or an efficiency advantage.
Record each delta with a unique ID, comparison category, common baseline, bidder response or difference, evidence or document reference, responsible party, potential commercial, programme, or technical effect, and current status.
Bid delta register:
| Delta ID | Category | Common baseline | Bidder response/difference | Evidence/reference | Responsible party | Effect | Status |
|---|---|---|---|---|---|---|---|
| D-01 | Documents/revisions | Common drawing/specification issue | Different revision or missing addendum | Drawing/addendum reference | Buyer/bidder | To be stated | Open |
| D-02 | Quantity/panel basis | Common area, panel schedule, and phases | Different take-off or panel count | Schedule/take-off | Buyer/bidder | To be stated | Open |
| D-03 | Materials/system | Common product and material basis | Alternative, substitution, or unpriced item | Product data/BOM | Bidder/design team | To be stated | Open |
| D-04 | Scope status | Same responsibility boundary | Included/optional/excluded difference | Scope schedule | Buyer/bidder | To be stated | Open |
| D-05 | Engineering/testing | Common deliverable/test brief | Different deliverables, test, or QA basis | Test/technical documents | Named party | To be stated | Open |
| D-06 | Factory/logistics | Common factory and delivery boundary | Packaging, customs, delivery, or storage difference | Logistics note | Supplier/carrier/buyer | To be stated | Open |
| D-07 | Installation/handover | Common site and handover boundary | Labor, supervision, replacement, or records difference | Installation/handover scope | Named party | To be stated | Open |
| D-08 | Commercial | Common currency, validity, and terms | Allowance, tax, duty, payment, or escalation difference | Commercial schedule | Buyer/supplier | To be stated | Open |
Use the register to prepare clarification questions. Do not convert a delta into a score or rank.
Stage 5: Issue Controlled Clarification Questions
Clarification should follow your procurement route. Some processes require material information to be issued to all bidders or through a formal addendum; others use a different method.
Ask comparable questions about:
- Drawing, specification, addenda, and clarification revisions
- Quantity, panel schedule, phases, and non-unitized areas
- System, glass/infill, finish, hardware, and alternative basis
- Engineering, BIM, calculations, mockups, testing, reports, and retesting
- Factory assembly, glazing, sealing, inspection, labeling, and release
- Packaging, delivery point, customs, unloading, storage, lifting, and damage
- Installation labor, supervision, adjustment, replacement, re-delivery, and handover
- Currency, taxes, duties, validity, payment, allowances, alternatives, escalation, exclusions, and programme
Controlled clarification register:
| Question ID | Category | Common question | Affected bidders | Reference | Owner | Response/date | Effect on status |
|---|---|---|---|---|---|---|---|
| Q-01 | Documents | Which drawing/specification revisions and addenda form the basis of your bid? | Named bidders | Document register | Buyer/bidder | To be recorded | Open |
| Q-02 | Quantity | Which area, panel schedule, phases, and non-unitized zones did you price? | Named bidders | Take-off/schedule | Buyer/bidder | To be recorded | Open |
| Q-03 | Materials | What system, glass/infill, finish, and alternative basis is included? | Named bidders | Scope/BOM | Bidder/design team | To be recorded | Open |
| Q-04 | Engineering/testing | What drawings, BIM, calculations, mockups, tests, reports, and retesting are included? | Named bidders | Technical scope | Named party | To be recorded | Open |
| Q-05 | Logistics | What delivery point, customs, unloading, storage, lifting, and damage assumptions apply? | Named bidders | Logistics schedule | Supplier/buyer | To be recorded | Open |
| Q-06 | Installation | Is labor, supervision, site adjustment, replacement, and handover included? | Named bidders | Installation scope | Supplier/buyer | To be recorded | Open |
| Q-07 | Commercial | Which taxes, duties, currency, validity, allowances, alternatives, escalation, and exclusions apply? | Named bidders | Commercial schedule | Buyer/supplier | To be recorded | Open |
Keep the original question, response, date, affected bidders, supporting document, potential effect, and resulting comparability status.
Same-Scope Comparison Matrix
Use this matrix to view all bidders against one baseline. It records comparability; it does not calculate a score or identify a winner.
| Category | Common baseline | Bidder A | Bidder B | Bidder C | Delta/evidence | Status |
|---|---|---|---|---|---|---|
| Documents/revisions | Common register/addenda | Used basis | Used basis | Used basis | Reference difference | Open/closed |
| Quantity/panels | Common take-off/schedule | Stated basis | Stated basis | Stated basis | Quantity/panel delta | Open/closed |
| System/materials | Common technical basis | Response/status | Response/status | Response/status | Product/finish delta | Open/closed |
| Glass/infill | Common schedule | Response/status | Response/status | Response/status | Make-up/area delta | Open/closed |
| Engineering/BIM | Responsibility matrix | Deliverables/status | Deliverables/status | Deliverables/status | Responsibility delta | Open/closed |
| Testing/QA | Common test/QA brief | Plan/status | Plan/status | Plan/status | Method/report delta | Open/closed |
| Factory work | Assembly/glazing/release boundary | Status | Status | Status | Factory delta | Open/closed |
| Logistics/delivery | Common point and responsibility | Status | Status | Status | Delivery/customs delta | Open/closed |
| Installation/handover | Common site boundary | Status | Status | Status | Labor/support delta | Open/closed |
| Commercial terms | Currency, validity, taxes, payment, programme | Terms | Terms | Terms | Commercial delta | Open/closed |
| Open questions | Clarification register | Questions | Questions | Questions | Unresolved items | Decision status |
If your project requires weighted scoring or an award method, define it separately with the authorized procurement team.
How to Interpret Totals Without Over-Interpreting Them
Before interpreting a total or unit rate, reconcile the stated basis for:
- Base bid, unit rates, alternatives, allowances, provisional items, and exclusions
- Currency, taxes, duties, insurance, escalation, and payment terms
- Delivery point, shipping, customs, unloading, storage, lifting, and installation
- Engineering, testing, factory work, replacement, handover, and programme dependencies
- Unresolved assumptions or differences recorded in the delta and clarification registers
A total may be lower or higher for reasons that cannot be established without the underlying scope and commercial documents. Normalization makes those differences visible.
Conditional Comparability Outcomes
| Outcome | Use when | Evidence expected | Next action |
|---|---|---|---|
| Comparable on stated basis | Documents, quantities, scope, responsibilities, commercial terms, and delivery assumptions are aligned or clearly qualified | Common register, schedules, scope statuses, delta log, and closed material clarifications | Record the basis and move to your next authorized review step |
| Not yet comparable | Material differences in documents, quantity, system, scope, or commercial basis make direct comparison misleading | Identified deltas with affected quotation lines and references | Reconcile the baseline, request revised responses, or issue common information |
| Requires clarification | Open items could affect scope, responsibility, technical interpretation, commercial terms, or programme | Question, owner, reference, response requirement, and potential effect | Obtain and record clarification, then reassess |
A quotation can remain "Requires clarification" even when its headline total is clear.
Common Same-Scope Comparison Errors to Avoid
- Comparing bids based on different drawing or specification revisions
- Missing addenda or distributing clarifications inconsistently
- Comparing different quantity or panel-schedule bases
- Treating a different system, glass/infill, finish, or alternative as an equivalent base bid without review
- Ignoring non-unitized areas, corners, transitions, openings, and work-by-others boundaries
- Comparing "technical support" or "testing included" without deliverables, method, agency, or report scope
- Mixing supply-only, delivered-to-site, and installed quotations
- Ignoring customs, taxes/duties, unloading, storage, lifting, replacement, and handover terms
- Adding allowances, alternates, or provisional items to one bid but not another without documenting the adjustment
- Converting currencies or tax treatment without a documented project basis
- Treating a lower total as proof of efficiency, quality, or better value
- Treating a delta as proof of supplier error without evidence
FAQ: Same-Scope Unitized Curtain Wall Comparison Questions
How do I compare unitized curtain wall quotations on the same scope?
Freeze the common drawings, specifications, revisions, addenda, quantities, panel schedule, technical basis, delivery point, and commercial assumptions. Then normalize scope and responsibility, record deltas, issue controlled clarifications, and classify the result as Comparable on stated basis, Not yet comparable, or Requires clarification.
Why do two unitized curtain wall quotations differ?
They may use different documents, quantities, system or material bases, inclusions, exclusions, alternatives, allowances, delivery points, installation boundaries, or commercial assumptions. Record each bidder's stated basis before interpreting the difference.
How do I check whether suppliers used the same drawings and revisions?
Compare each quotation's document register, drawing and specification revisions, addenda, clarification responses, model files, quantity take-off, panel schedule, and assumptions against the common baseline. Record any difference as a bid delta.
What should a curtain wall bid comparison matrix include?
A common baseline, bidder responses, delta or evidence reference, and status for documents, quantities, system/materials, glass/infill, engineering/BIM, testing/QA, factory work, logistics/delivery, installation/handover, commercial terms, and open questions.
How do I compare quotation inclusions, exclusions, alternatives, and allowances?
Use the same status and scope categories for each bidder. Record the base bid, alternatives, allowances, provisional items, exclusions, assumptions, qualifications, responsibility, supporting evidence, and any unresolved effect.
When is a unitized curtain wall quotation not comparable?
It is Not yet comparable when material differences in documents, quantities, system, scope, delivery, responsibilities, or commercial basis make a direct comparison misleading. It Requires clarification when an open question could affect the comparison but the basis may still be reconciled.
How should I record curtain wall bid clarification questions?
Use a controlled register with the question, category, affected bidders, reference, owner, response date, supporting document, potential effect, and resulting comparability status.
Should the lowest unitized curtain wall quotation be selected?
Not automatically. A lower total may reflect different scope, exclusions, alternatives, allowances, taxes, duties, delivery, or installation assumptions. Reconcile those first, then make the commercial decision.
Conclusion: Compare the Basis Before the Price
A same-scope comparison is a documented process, not a total-price race:
- Freeze the common basis. Confirm documents, revisions, addenda, quantities, panel schedules, technical requirements, delivery conditions, and commercial assumptions.
- Normalize and record. Compare scope statuses, responsibility boundaries, bid deltas, evidence, and clarifications across the returned quotations.
- Classify decision readiness. Use Comparable on stated basis, Not yet comparable, or Requires clarification before any award decision.
