How to Read a Sub Bid for Scope Gaps Before It Hits Your Estimate

A sub bid is not a number. It’s a document full of assumptions, exclusions, and carefully worded language designed to protect the sub, not you. Plugging a number into your estimate before you actually read the bid is one of the most reliable ways to lose margin on a job.

Scope gaps don’t show up as line items. They hide in what the bid doesn’t say.

Start With the Exclusions, Not the Total

Most estimators glance at the total first. That’s the wrong place to start. Go straight to the exclusions list. That’s where subs define the edges of their scope, and those edges rarely line up perfectly with your spec.

Common exclusions to flag immediately:

• Permits, inspections, or fees
• Bonds or certified payroll
• Temporary protection, hoarding, or site conditions
• Coordination drawings or BIM participation
• Specific materials called out in the spec but not mentioned in the bid

If a sub has excluded bonding and your contract requires it, that delta is yours to eat unless you catch it now. Same with prevailing wage. A bid submitted without certified payroll language on a public job can blow up the whole number.

After exclusions, look at what the bid is silent on. Silence is not inclusion. If your spec calls for stainless steel hangers and the sub’s bid says “hangers” with no qualifier, don’t assume. That’s a conversation you need to have before bid day, not a clarification you want to make after award.

Check the Bid Against the Actual Spec

Pull up the relevant CSI MasterFormat section for that trade and read the sub’s bid against it line by line. This takes time. It’s also the only way to know what you’re actually buying.

Look specifically for:

Scope boundaries. Where does this sub’s work start and stop? Does it include demolition of existing conditions? Patching after penetrations? Startup and commissioning? These are common split-scope areas that fall through the cracks between trades.

Alternates and allowances. If the sub has built in allowances for something, you need to know what assumptions they used. An allowance that’s half of what the spec requires is a gap, not coverage.

Qualifications buried in the body. Exclusions lists are only part of it. Subs often bury conditions in the narrative, “based on single mobilization,” “assumes unobstructed access,” “per plans dated X.” If your plans have been revised since that date, the bid may not reflect current scope.

Build a Scope Comparison Before You Buy

The most disciplined estimators don’t compare sub bids to each other first. They compare each bid to the spec. Once you know what each sub has and hasn’t included, the comparison becomes meaningful. Before that, you’re just comparing numbers without knowing what they represent.

Create a simple matrix: trades across the top, scope items down the side. Mark what’s included, what’s excluded, and what’s unclear. That last column is your follow-up list. Every unclear item needs a phone call or written clarification before that number goes in your sheet.

This process also protects you post-award. If a dispute comes up over scope, you have documentation of exactly what you understood the bid to include at the time you used it. That’s worth more than the hour it takes to build.

According to ASA subcontractor advocacy guidance, scope disputes between GCs and subs are among the most common sources of payment conflicts on commercial projects. Most of them trace back to assumptions made during bidding that neither party wrote down.

Reading a sub bid carefully is not extra work. It’s the actual work. The number is just the output.

Comms Center keeps a full searchable history of every bid submission and follow-up conversation tied to each subcontractor, so when you need to go back and confirm what a sub said about a scope item, it’s right there. No digging through email threads or trying to remember a phone call. See how it works at commscenter.com.