Compare siding proposals by bringing their scope onto the same basis before comparing totals. Mark each item included, excluded, allowance or unknown. Obtain written clarifications for differences that affect price or performance. A low headline total is not a comparable price when another proposal includes work it leaves unpriced.
What needs a row in the comparison?
Start with the owner’s shared scope and add a column for each bidder. Keep the bidder’s actual wording available beside your summary. Do not translate “as needed” into “included” unless the quantity and payment treatment are clear.
| Item | Clarification to request |
|---|---|
| Removal and disposal | Layers, affected areas, waste handling and cleanup included |
| Access | Equipment, staging, resident protection and repeated mobilization |
| Substrate repair | Included quantity, unit prices and approval procedure |
| Water-control layers | Product and connections at each identified detail |
| Siding and trim | Exact products, finishes, exposure and accessories |
| Other trades | Roof, electrical, window or balcony responsibilities |
| Approvals | Applications, drawings, fees and inspection coordination |
| Closeout | Punch list, records, warranties and maintenance information |
Technical omissions matter even when their price is unknown. Building America identifies coordination at roof-wall flashing as part of the work sequence; a roofing exclusion therefore deserves a specific explanation when those intersections are in scope. Roof-wall flashing guidance.
How does normalization change the apparent winner?
Consider two invented bids for an identical hypothetical project. These amounts illustrate comparison arithmetic only and are not local market prices.
| Comparison item | Bid A | Bid B |
|---|---|---|
| Headline proposal | $260,000 | $278,000 |
| Defined access/protection work omitted from headline | $12,000 | Included |
| Defined trim work omitted from headline | $9,000 | Included |
| Comparable defined-work total | $281,000 | $278,000 |
| Concealed sheathing repairs | Unresolved | Unresolved |
On the stated scope, Bid A’s apparent $18,000 advantage becomes a $3,000 disadvantage after the two written additions. Neither proposal is fully comparable until the treatment of concealed repairs is resolved. Do not invent a sheathing quantity or unit price to make the table look complete.
This arithmetic does not choose the contractor. References, relevant experience, capacity, communication, contract terms and the quality of the proposed details still require review. The table simply prevents one narrow error: treating different work as the same purchase.
How do allowances and unit prices differ?
An allowance is money provisionally included for a defined but incompletely determined item. A unit price sets a price for a measurable quantity. An alternate is a separately priced choice. Label them separately, and ask what happens if actual work is above or below the allowance.
For sheathing repairs, ask for the measurement unit and whether disposal, labor, fasteners and adjacent layer repairs are included. Record minimum charges and access costs if applicable. Identify who measures, documents and authorizes the work. Without those terms, two matching unit prices may still describe different obligations.
The cost guide explains how contractor allowances differ from the owner’s contingency. Preserve that difference in the board presentation; it helps prevent the same uncertainty being counted twice.
What if products or details differ?
Ask for an alternate on the owner’s specified basis and a separate description of the proposed substitution. Compare the product identity, wall thickness, trim, water-control connections, finish, maintenance and warranty terms. A claimed upgrade can create changes elsewhere in the assembly.
Record which differences require design review. A spreadsheet cannot determine whether an assembly is suitable for the building. If one bidder identifies a genuine flaw in the shared scope, issue the resulting clarification to all remaining bidders so they price the same corrected work.
Use the materials guide for the questions that belong beside a product substitution. The RFP guide can help prevent many of these differences in the next bid round.
What should be resolved before award?
Complete a clarification log with each question, bidder response, price effect and final decision. Incorporate the accepted responses into the executed agreement. A helpful email should not remain outside the contract if the project team is relying on its promise.
Use the bid comparison tool to organize the figures and record uncertainty. Bring the findings into the complete replacement plan. Property managers can share a project package containing the common scope, proposals and outstanding questions.