How to Read a Subcontractor Bid Without Getting Burned on Scope Gaps
The line that reads "install per plans" with no drawing reference is the one that becomes a $14,000 change order. Pin every bid item to a specific drawing number, spec section, and revision date before you sign, so the gap shows up on paper instead of on the poured slab.
A subcontractor bid is a priced promise about a defined scope of work. When the scope is fuzzy, the price is fiction. Most disputes I see do not start with a bad number. They start with a clean-looking number sitting on top of three words of scope that the GC and the sub read two different ways. Learning to read a subcontractor bid means reading the scope language as hard as you read the dollar figure.
What is a subcontractor bid actually made of?
A subcontractor bid is a document with six working parts: a scope narrative, priced line items, a list of inclusions, a list of exclusions, assumptions and allowances, and commercial terms (schedule, payment, retention, validity). A bid missing any of those is not cheaper. It is incomplete, and you are carrying the difference.
Read them in this order:
- Scope narrative. What trade work, tied to which drawings and spec sections by number and revision date. "Per A-301 Rev 3, dated 04/18" is a scope. "Per plans" is a guess.
- Line items. Quantity, unit, unit price, extended price. A lump sum with no quantity behind it hides the math.
- Inclusions. What the sub is promising to furnish and install.
- Exclusions. The most important section in the whole document. This is where the gaps live.
- Assumptions and allowances. Dollar placeholders for undefined work. A $5,000 allowance is a hole with a number written next to it.
- Terms. Retention (commonly 5 to 10 percent), payment timing, how long the price holds, and lead times on long-lead material.
I have read thousands of these, and the bid that wins on price almost always wins by quietly excluding something the next bid included. The job of reading is to find that something before the contract is signed.
Where do scope gaps hide in a bid?
Scope gaps hide in vague verbs and missing nouns. They live in the exclusions you skim and the assumptions you accept without pricing the alternative.
Watch for these exact phrases:
- "Per plans" / "per code" with no reference. Which plan set, which revision. Codes change, and "per code" lets a sub install the minimum while you assumed the detail on the drawing.
- "By others." This is the classic gap. The electrician excludes the trenching "by others," the GC assumed the electrician trenched, and now nobody priced 180 feet of trench. That is a change order on day one.
- "Normal" or "standard" conditions. Standard soil, standard access, standard hours. The moment the job needs night work or hits rock, the price moves.
- Allowances stacked on allowances. Three $4,000 allowances in a $90,000 bid means $12,000 of the price is undefined. You are bidding a range, not a number.
- Missing connection work. Where two trades meet is where scope falls through. Who flashes the curb the roofer set. Who fireproofs the steel the erector left bare. Name the boundary or pay for it twice.
The American Institute of Architects publishes standard scope and division language for exactly this reason, and the AIA document families map cleanly to how subs divide their bids. Comparing a bid against a known division structure makes the missing line obvious.
How do you compare two bids that are not apples to apples?
You normalize them. Build a scope matrix, list every work item the job requires down the left, and check off which bid actually covers it. The cheapest column with the most blank checkmarks is usually the most expensive job once the change orders land.
Here is what a normalized comparison looks like on a concrete flatwork package:
| Scope item | Sub A ($82,000) | Sub B ($76,500) | Sub C ($88,000) |
|---|---|---|---|
| Fine grade / compaction | Included | Excluded ("by others") | Included |
| Vapor barrier under slab | Included | Included | Included |
| Rebar furnish + place | Included | Place only, furnish excluded | Included |
| Saw cut control joints | Included | Excluded | Included |
| Pump truck | Included | Excluded | Included |
| Concrete washout / cleanup | Included | Excluded | Included |
| Price validity | 30 days | 14 days | 45 days |
Sub B looks $5,500 cheaper at the top. Once you price the four excluded items (grade, rebar furnish, saw cutting, pump truck) Sub B lands around $9,000 to $11,000 above Sub A. The low bid was never low. It was just shorter.
What questions should you ask before signing?
Ask the questions that force the gap into writing. Every answer becomes part of the contract scope, which is where you want it when the dispute comes.
- Which drawing numbers and revision dates is this price based on. Get the set and date in writing.
- What is on your exclusions list that the spec requires. Walk every exclusion against the spec.
- What does each allowance cover, and what is your unit price if it runs over. Convert allowances to unit prices wherever you can.
- Who handles the work at the boundary with the adjacent trade. Name the trade and the task.
- What are your lead times on long-lead material, and is that price held through the schedule. Switchgear and certain MEP equipment can run 20 to 40 weeks; a 14-day price validity on a 30-week lead is a trap.
- What is your retention, and what triggers final release. Confirm it matches your prime contract so you are not floating retention the owner already released.
- Are license, general liability, and any required bond current, and will the certificate name this project as additional insured.
That last one is not paperwork. An unvetted sub with lapsed coverage turns one accident into your liability. Verifying license, insurance, and bonding before award is the cheapest risk reduction on the job, and it is the core of what we built SubSource to do. The Associated General Contractors has long pushed prequalification as standard practice for the same reason: the cost of a failed sub dwarfs the cost of checking.
How much does a scope gap actually cost?
A scope gap costs the change order plus the schedule. A mid-job change order carries 15 to 20 percent markup on the added work, and the real damage is usually the days lost, not the dollars added.
Run the math on the "by others" trench from earlier. The excluded trenching comes back as a $6,200 change order. That work was not scheduled, so it pushes the electrical rough-in four days. The four days cascade into the inspection window, the drywall crew you booked sits or reschedules, and you eat either standby or a two-week gap before they return. The $6,200 line on paper is a $15,000 to $20,000 event on the schedule. The gap was three words in an exclusions list you skimmed.
Catch it at bid review and it costs you one phone call.
On your next bid, before you award anything, build the scope matrix and put every exclusion from every bidder in one column. Then walk that column against the spec line by line, and write the missing items back into the awarded sub's scope of work before the contract is signed.
FAQ
What is a scope gap in construction? A scope gap is work the project requires that no subcontractor's bid actually covers, usually because one sub excluded it assuming another would handle it. The gap surfaces mid-job as a change order.
Why is the cheapest subcontractor bid often the most expensive? Because the low number frequently excludes scope that competing bids included. Once you price the excluded items and the schedule delay they cause, the low bid commonly ends up costing more than the next bid up.
What should I verify before awarding a subcontract? Confirm the bid references specific drawings and revision dates, review every exclusion against the spec, convert allowances to unit prices, and verify the sub's license, general liability insurance, and any required bond are current before signing.