How to Bid a Construction Job: Complete Guide for GCs and Subcontractors
Bidding a construction job is the process of reading a set of plans and specifications, quantifying every piece of work shown in the documents, pricing that work accurately, and submitting a number you're willing to build the project for. The bid determines whether you win the work and whether you'll make money doing it. Get it right and you build your backlog with profitable projects. Get it wrong and you either lose the bid or win a project that costs you money.
Before You Bid: Reading the Invitation
Every bid starts with an Invitation to Bid (ITB) — the formal document from the owner or architect that tells contractors what's being built, when bids are due, and what format the bid must take. Before you spend a single hour on the estimate, read the ITB carefully and make a deliberate bid/no-bid decision.
The ITB tells you the critical constraints: bid date and time, pre-bid meeting schedule (mandatory or optional), plan availability (where to download or pick up), bid form requirements, bonding requirements, insurance minimums, and any prequalification requirements. Missing any of these can disqualify your bid regardless of price.
Bid/No-Bid Checklist
The most expensive bid is the one you shouldn't have submitted. Every hour your estimating team spends on a project you can't win or shouldn't pursue is an hour they could have spent on a better opportunity.
Step 1: Review the Plans and Specifications
Before measuring a single quantity, review the entire plan set to understand what's being built. This means looking at every sheet — architectural, structural, mechanical, electrical, plumbing, civil, landscape — and reading the relevant specification sections. The goal is to build a complete mental model of the project before starting the takeoff.
During plan review, you're looking for three things:
- 1.Scope definition: What work is included? What's the GC's responsibility versus the subs? Are there owner-furnished items?
- 2.Red flags: Coordination conflicts between disciplines, ambiguous details, spec requirements that don't match the drawings, incomplete information that will generate RFIs.
- 3.Complexity drivers: Unusual conditions, difficult access, phasing requirements, long-lead equipment, or anything that will affect labor productivity or require special methods.
This is the step most estimators shortchange under time pressure — and the step where the most expensive errors originate. A scope gap missed during plan review becomes a cost overrun during construction.
Step 2: Attend the Pre-Bid Meeting and Site Walk
If the ITB includes a pre-bid meeting — especially a mandatory one — attend. The pre-bid meeting is where the owner and architect clarify the project scope, answer questions, and sometimes reveal information that isn't in the documents. On renovation or addition projects, the site walk is essential for understanding existing conditions that the drawings may not fully capture.
During the site walk, document: existing conditions that differ from what's shown on the drawings, access constraints for deliveries and equipment, site logistics challenges (staging area, laydown, parking), utilities locations and available capacity, and any demolition or abatement scope that the drawings may understate.
Submit pre-bid RFIs for anything that's unclear in the documents. Getting a written clarification from the design team before the bid deadline is free. Discovering the same ambiguity during construction is expensive.
Step 3: Perform the Quantity Takeoff
Quantity takeoff is the process of measuring and counting every item of work from the drawings. For a GC, this typically covers self-performed work: concrete, site work, general carpentry, drywall, doors and hardware, specialties, and general conditions. Specialty trades (MEP, steel, roofing, elevator) are covered by subcontractor bids.
Organize the takeoff by CSI division or by area of the building — whichever matches your estimating software and historical cost database. Be methodical: go sheet by sheet, check every room, count every opening. The most common takeoff errors are omissions, not miscounts.
Takeoff Best Practices
Work from the specs, not just the drawings. The specifications define material types, quality standards, and installation requirements that affect unit costs. A takeoff that ignores the specs prices the wrong materials.
Include waste factors. Standard waste factors: concrete 5-8%, framing lumber 10-15%, drywall 10%, flooring 10-15%. Ignoring waste means underpricing material by 10% or more.
Mark up the drawings as you go. Color-code or highlight each item as you take it off. Unmarked areas are either missed scope or items you assumed were in a sub's bid.
Cross-check quantities against benchmarks. If your concrete takeoff gives 4.5 CY per 1,000 SF on an office building and your historical average is 6.2 CY, either you found genuine efficiencies or you missed scope.
Step 4: Solicit and Level Subcontractor Bids
On a typical commercial project, 60-80% of the project cost comes from subcontractors. Managing the sub bid process is as important as the GC's own takeoff. Start soliciting sub bids early — don't wait until bid week. Give subs enough time to produce quality bids, and they'll give you better pricing and fewer scope exclusions.
When sub bids come in, level them before selecting. Bid leveling means normalizing each bid to an apples-to-apples comparison:
- - List every scope item in a spreadsheet with one column per sub
- - Mark included, excluded, and clarified items for each sub
- - Add back the cost of any excluded items so you're comparing total scope
- - Check alternates and unit prices — some subs are low on base but high on alternates
- - Verify that each sub's scope interpretation matches the GC's scope breakdown
The lowest bid isn't always the best bid. A sub who's low because they missed scope will either produce a change order during construction or fail to complete the work. Use the leveling process to understand why each bid is priced where it is.
Step 5: Price the Work
With quantities complete and sub bids leveled, assemble the total project cost. The estimate has four major components:
Direct Costs (Self-Performed Work)
Labor (crew hours x fully-burdened rates), materials (quantities x unit prices + waste + tax), and equipment (rental rates x duration or owned equipment charges). Use current labor rates — not last year's. Check material prices with suppliers within the last 30 days.
Subcontractor Costs
The leveled sub bids for each specialty trade, plus any scope gaps identified during leveling that the GC needs to carry separately. If no sub bid covers a scope item, the GC must either self-perform it or plug a budget number.
General Conditions
Project management, superintendent, site trailer, temporary utilities, dumpsters, safety, cleanup, small tools, project insurance, and bonds. Price these monthly and multiply by the schedule duration — then add a buffer for likely delays.
Overhead and Profit
Home office overhead (typically 3-8% of project cost) covers the firm's operating expenses not charged to specific projects. Profit (typically 2-6% for competitive hard bids) is what the firm earns for taking the project risk. Together, O&P typically runs 5-12% of the total direct cost.
Step 6: Final Review and Bid Submission
Before submitting, run through a final sanity check:
Cost per SF check: Does your total cost per square foot align with historical benchmarks for this building type? If it's significantly lower, you probably missed scope. If it's significantly higher, check your pricing assumptions.
Addenda incorporation: Have all addenda been reflected in the estimate? Check that every addendum item changed the affected line items — including cascading impacts on related trades.
Division coverage: Walk through every CSI division and verify each one is covered — either by the GC's estimate, a sub bid, or a conscious exclusion. Missing entire divisions is more common than you'd think.
Math verification: Check column totals, subtotals, and the grand total. Transposition errors on bid day have cost contractors millions. Have someone other than the estimator verify the math.
Complete the bid form exactly as specified in the ITB. Include all required attachments: bid bond, subcontractor list, non-collusion affidavit, and any other required certifications. Submit before the deadline — late bids are returned unopened.
If submitting alternates or exclusions, state them clearly on the bid form. Vague exclusions create disputes; specific exclusions protect your scope.
Bid-Day Mistakes That Cost Money
Cutting contingency to win
When the bid total is higher than expected, the first instinct is to cut contingency. This is the worst possible response. If your estimate is accurate, you need less contingency. If your estimate has gaps, cutting contingency means you'll absorb those gaps out of profit. Contingency should be proportional to your confidence in the scope — not inverse to your desire to win.
Using stale sub bids
A sub bid from last Tuesday might be withdrawn by bid day if the sub won other work or recalculated their number. Confirm every sub bid within 24 hours of submission. "I'm using your number" is a 30-second phone call that prevents a 6-figure problem.
Ignoring the specifications
The drawings show what to build. The specs define how to build it and what materials to use. An estimate that prices from drawings alone misses specification requirements that affect material grades, installation methods, testing requirements, and warranty obligations.
Not reading the contract
The contract terms define risk allocation: who pays for weather delays, who owns differing site conditions, what the change order process is, and how disputes are resolved. A project with aggressive liquidated damages, broad indemnification clauses, or no-damage-for-delay provisions carries more risk — and the bid price should reflect that.
Bidding as a GC vs. Bidding as a Subcontractor
The core estimating process is the same for GCs and subs, but the focus differs:
GC Focus
- - Full project scope coordination
- - Sub bid management and leveling
- - General conditions and schedule-driven costs
- - Cross-discipline coordination risk
- - Bonding and insurance for entire project
Subcontractor Focus
- - Detailed takeoff within one or two trades
- - Clear scope inclusions and exclusions
- - Labor productivity based on crew composition
- - Material pricing with supplier quotes
- - GC relationship and payment track record
How AI Plan Review Makes Bidding Faster and More Accurate
The hardest part of bidding isn't the math — it's the plan review. Reading a 200-sheet plan set thoroughly enough to catch every scope gap, specification conflict, and coordination issue is a 15-20 hour task that most estimators compress into 3-4 hours because they're bidding multiple projects simultaneously.
SheetIntel automates the systematic plan review that Step 1 describes. It reads every sheet, cross-references the specifications, and flags the scope gaps, coordination conflicts, and ambiguities that estimators miss under time pressure. The estimator gets a prioritized list of issues to investigate — not a replacement for their expertise, but a systematic check that ensures they're estimating complete scope.
The contractors who win consistently aren't the ones who bid the lowest — they're the ones who understand the true scope better than their competitors. AI plan review gives every estimator the thoroughness that used to require decades of experience.
Key Takeaways
- →The bid/no-bid decision is the highest-leverage choice — don't invest 100 estimating hours on a project you can't win or shouldn't pursue.
- →Plan review before takeoff is the most under-invested step and the source of most estimating errors. Review every sheet and spec section before measuring anything.
- →Sub bid leveling is as important as the GC's own takeoff — the lowest bid isn't the best bid if it's missing scope.
- →Price general conditions off the schedule, not a percentage — two extra months at $100K/month is a $200K error that no percentage estimate catches.
- →Never cut contingency to win. If the bid is too high, the problem is in the scope or pricing, not the contingency.
- →The contractors who win consistently understand true scope better than their competitors — AI plan review gives every estimator that advantage.
Bid on Complete Scope
SheetIntel reviews your plan sets before the takeoff begins — flagging scope gaps, coordination conflicts, and spec ambiguities so your bid reflects the true cost of the work.
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