Commercial Construction Estimating: The Complete Pre-Bid Guide for GCs

Before investing 40-100 hours in an estimate, the GC evaluates whether the project is worth pursuing. Key factors: project type and size relative to the firm's experience, current backlog and bonding capacity, geographic location, client reputation for payment and change order fairness, and the competitive landscape (how many other GCs are bidding).

The bid/no-bid decision is one of the highest-leverage choices a GC makes. Estimating a project the firm shouldn't bid wastes the estimating team's most scarce resource: time during the bid period.

The estimator reviews the entire plan set — every sheet, every discipline — to understand the full scope of work before starting any quantity takeoff. This is where the estimator builds a mental model of the project: what's being built, how it's constructed, where the complexity lives, and what's likely to cause problems.

The plan review should identify: scope gaps between disciplines (work shown on one set of drawings but not addressed on another), specification requirements that affect material selection or installation methods, coordination challenges between trades, and anything that looks unusual, unclear, or incomplete.

This is the most under-invested step in most estimating workflows. Under time pressure, estimators skip the holistic review and jump straight to takeoff — which means they discover scope gaps one at a time during construction rather than all at once during estimating.

The estimator measures and counts every item of work from the drawings: linear feet of wall, square feet of flooring, cubic yards of concrete, number of fixtures, tons of structural steel. On a commercial project, the GC typically does detailed takeoff on self-performed work (concrete, carpentry, general conditions) and relies on subcontractor bids for specialty trades (MEP, steel, roofing, curtain wall).

Modern takeoff uses digital tools — Bluebeam, PlanSwift, On-Screen Takeoff — to measure quantities directly from digital drawings. But the tool only measures what the estimator tells it to measure. If the estimator doesn't see a scope item in the drawings, no tool will capture it.

Takeoff accuracy depends entirely on the quality of the plan review. An estimator who missed a specification requirement during plan review will produce a takeoff that's accurate for the wrong scope.

For specialty trades — mechanical, electrical, plumbing, structural steel, roofing, elevators, fire protection — the GC solicits bids from qualified subcontractors. This process runs in parallel with the GC's own takeoff work and typically intensifies in the final days before bid submission.

Bid leveling is the process of comparing sub bids on an apples-to-apples basis. Different subs include and exclude different scope items, carry different allowances, and interpret the drawings differently. The estimator must normalize these differences to identify the true low bidder — not just the lowest number.

The most dangerous sub bid is the one that's low because it's missing scope. Using that bid without catching the gap means the GC either absorbs the cost or generates a contentious change order during construction.

Once quantities are complete and sub bids are leveled, the estimator applies unit costs to self-performed work (labor rates, material prices, equipment costs), adds general conditions (project management, superintendent, temporary facilities, insurance, bonds), and applies the firm's overhead and profit markup.

The markup decision balances competitiveness against risk. A higher markup covers more risk but reduces the chance of winning. A lower markup wins more work but leaves less room for estimating errors and unforeseen conditions. The most profitable GCs are the ones who can carry lower markups because their estimates are more accurate — they understand the true scope and price the actual risk.

Contingency is often the first thing cut when the bid total comes in too high. This is exactly backwards: contingency should be proportional to the estimator's confidence in the scope, not inverse to the competitive pressure.

Before submitting, the estimate undergoes a final review: Does the total cost per square foot align with historical benchmarks for this building type? Are all specification divisions covered? Are the sub bids current and complete? Are there any last-minute addenda to incorporate?

The final hours before bid submission are when the most consequential errors occur. Last-minute sub bids arrive, addenda change scope, and mental fatigue from weeks of estimating increases the risk of transposition errors, missed items, and incorrect math.