# Scope Gap Detection > Scope gap detection uses language models to compare subcontractor proposals with a construction bid package. It flags work that no sub has priced, that a sub has excluded, or that overlaps between trades before the general contractor commits to a number. - Stages: Estimating - Concepts: LLMs, Document Extraction - Published: 2026-08-28 - Canonical: https://buildr.com/library/scope-gap-detection ## Why it matters in construction Scope gaps can turn a winning bid into a losing project. The estimate carries the low mechanical number, but that proposal excludes controls. The team assumes electrical carries the controls scope, and electrical never sees it. Six months later there is a 180,000 dollar change order the owner will not pay and a margin that falls from 6 percent to 2. These gaps hide in the qualifications and exclusions sections of proposals, in language that varies from sub to sub, and they land on bid day when nobody has time to read every page of every bid. Scope gap detection is the systematic read estimators wish they had time to do. ## How it works 1. **Define the package.** The estimator loads the bid package scope for each trade, ideally as an itemized list tied to spec sections and drawing references. 2. **Extract from proposals.** The tool reads each sub proposal and pulls its inclusions, exclusions, alternates, clarifications, and assumptions into structured fields. 3. **Match and compare.** The tool matches extracted items to the package scope list and flags three conditions: excluded by the sub but in the package, in the package but absent from every proposal, and claimed by proposals in two different trades. 4. **Cross-check the documents.** Where drawings and specs are loaded, the tool also flags items that appear in the documents but not in the package descriptions. Those are gaps in the package itself. 5. **Present for review.** Each gap shows the exact proposal language and package reference, ranked by estimated dollar exposure, and the estimator resolves it by calling the sub, plugging a number, or dismissing it. The tool has to quote the source. "Sub excludes permits" only helps if the estimator can see the sentence and decide whether it applies. ## Example in practice Consider a commercial GC bidding a 9 million dollar ground-up branch bank. Mechanical proposals come in from four subs, electrical from five, and the estimator has ninety minutes before the bid is due. Scope gap detection flags 14 items across the two trades. The low mechanical sub, 40,000 dollars under the next bidder, excludes building automation controls and temperature control wiring. Two electrical subs also exclude control wiring, and the third is silent on it. Nobody has priced the 6-inch condensate drain tie-in shown on P-201. The estimator calls the low mechanical sub, confirms it will add controls for 52,000 dollars, plugs 4,000 dollars for the condensate tie-in, and submits a bid that is 8,000 dollars higher but does not leave a 90,000 dollar gap. ## Go deeper - [How to Level Subcontractor Bids: A Step-by-Step Methodology for Commercial GCs](/blog/how-to-level-subcontractor-bids.md) - [Why Bid Leveling Takes Forever (and What Top Estimators Do Differently)](/blog/bid-leveling-estimating-ai-efficiency.md) - [AI Bid Leveling in Construction: A GC's Practical Guide](/blog/ai-bid-leveling.md) ## How Buildr applies this Buildr compares every sub proposal to your bid package and flags exclusions and unpriced scope in the leveling sheet. See [Buildr Estimating](/estimating). ## Related terms - [AI Bid Leveling](/library/ai-bid-leveling.md): AI bid leveling reads subcontractor proposals, pulls out prices and exclusions, and puts them into a like-for-like comparison. It helps estimators judge complete scope before they award work instead of treating the lowest number as the answer. - [AI Plan and Spec Review](/library/ai-plan-and-spec-review.md): AI plan and spec review uses language models to compare a construction drawing set with its specification book. It flags conflicts, missing information, and risk items for the preconstruction team to review before pricing. - [Structured Data Extraction](/library/structured-data-extraction.md): Structured data extraction uses AI to turn unstructured construction documents, such as sub proposals, RFPs, and specs, into typed fields like line items, prices, exclusions, and dates that can be sorted, compared, and loaded into an estimate or CRM. - [Grounding and Citations](/library/grounding-and-citations.md): Grounding ties an AI answer to specific source material rather than the model's general knowledge. Citations show where each claim came from. In construction, that might mean pointing to Section 09 29 00, paragraph 3.4, for a level 5 finish requirement. - [Human-in-the-Loop](/library/human-in-the-loop.md): Human-in-the-loop is an AI design pattern in which a person reviews, corrects, or approves the model's output before it takes effect. In construction, an estimator still owns the award and a BD lead still approves a pipeline update, while the AI handles reading and drafting. ## Referenced by - [AI Takeoff](/library/ai-takeoff.md): AI takeoff uses computer vision and language models to read construction drawings, identify building elements, and count or measure quantities so estimators can price a project without tracing every sheet by hand. ## FAQ ### What kinds of gaps does AI catch? Explicit exclusions in a proposal that the bid package includes, scope items in the package that no proposal mentions at all, and items two trades both claim, which usually means a coordination problem or double-counting. ### Can it catch gaps in scope that was never in the bid package? Partly. If the drawings and specs are loaded too, it can flag items shown on the drawings that the bid package scope descriptions never mention. It cannot catch things missing from both the documents and the package. ### How do we avoid false alarms? Show the source text for every flag and let estimators dismiss items with a reason. Depending on the tool, those decisions can help tune it to the firm's scope conventions, such as always carrying firestopping with drywall.