General Conditions Cost Management: The Overhead You're Probably Underestimating

General conditions (often abbreviated GCs, though the same abbreviation is used for "general contractor") are the project-specific overhead costs — the site-level infrastructure and management needed to run the project. They're distinct from direct construction costs (labor, materials, subs building the work) and from company-level overhead (home office rent, executives). GCs are typically 6-12% of direct construction cost on commercial work, sometimes higher on complex or difficult projects.

Getting general conditions right matters for bid competitiveness (too much makes bids uncompetitive), profitability (too little means losing money on each project), and schedule-impact claims (general conditions are the basis for extended-duration claims). This post covers what goes into general conditions, how to estimate it, and how to manage it during execution.

General Conditions Cost Categories

The typical categories of general conditions costs:

The list is long and project-specific. Some categories vary significantly by project type (healthcare projects have specialized requirements, public projects have specific documentation overhead). Estimating general conditions requires item-by-item consideration, not a percentage-of-direct-cost rule.

Duration-Dependent vs Fixed Costs

Costs have different relationships with project duration:

The distinction matters for duration extension analysis. When a project extends, duration-dependent costs accrue; fixed costs don't. A schedule claim for extended general conditions can only reasonably include the duration-dependent portion. Understanding the mix is essential for both estimating and claims.

Staffing Estimates

Project management staffing is the largest general conditions cost for most projects:

Staff burden costs (salary plus benefits, taxes, insurance) typically run 35-45% on top of base salary. A $120K-per-year superintendent costs $160K-$175K fully burdened, or roughly $14K per month. Missing one month of superintendent in duration estimating is $14K directly underestimated.

Project Duration Matters

Duration-dependent cost make duration estimating essential to general conditions:

A project estimated at 12 months that actually takes 15 months has 25% more duration-dependent general conditions than estimated — a significant hit to margin if not recovered through schedule extension claims.

Site Office Costs

Site office is a significant category:

Site office costs add up. A project with three trailers (GC office, conference/plans, sub offices) for 18 months runs $75K+ just in trailer rental, before utilities, setup, and furnishings. Site office is often underestimated because the component costs don't feel individually large.

Temporary Utilities

Temporary utility costs:

Temporary power is often underestimated. Early estimates based on office and light tool loads don't anticipate the welding, heavy tool, and equipment loads during structural and MEP phases. Sizing and estimating based on peak loads, not average, produces more accurate cost.

Site Security

Security costs vary significantly:

Urban projects and high-theft-risk projects require more security than suburban or remote sites. Security costs on a downtown project can exceed the site office costs; on a remote greenfield site they may be minimal.

Cleanup and Waste

Cleanup varies by project but is substantial on larger work:

On LEED or high-performance projects with recycling targets, waste management adds cost beyond standard dumpster hauling. Specific separation, documentation, and verification can add 20-40% to cleanup costs.

Managing General Conditions During Execution

During execution, general conditions needs management:

General conditions management is as important as direct cost management, but often gets less attention. Projects that track GC costs carefully during execution catch overruns early; projects that treat GCs as a lump sum to be reconciled at the end often discover significant overruns too late to correct.

Claims for Extended General Conditions

When projects extend, general conditions claims:

Extended general conditions claims are common when projects extend due to owner actions or circumstances. Documentation of actual GC costs during the extension — not estimated — supports the claim. Contractors who can produce detailed actual GC cost reports recover; those relying on estimates often don't.

Common Estimating Errors

Common general conditions estimating errors:

Checklists and historical data from similar projects help catch estimating errors. Companies with good post-project cost analysis build databases that inform future estimates; companies without post-project analysis repeat estimating patterns that produced past misses.

Bottom Line

General conditions cost management is one of the most consistently underestimated areas in construction estimating and one of the most consistently overrun during execution. Systematic estimating — category-by-category, distinguishing duration-dependent from fixed costs, using realistic durations, applying historical data, including typically-overlooked items — produces more accurate bids. Active management during execution — monthly variance tracking, staff level management, closeout phase adjustments — keeps actual costs close to estimate. Extended general conditions claims based on actual documented costs support recovery when schedule extends. Contractors who treat general conditions as a discipline produce better bid competitiveness and better margin consistency than contractors who treat it as a gut-feel markup. The discipline isn't complicated; it's just consistent attention to the category of cost that's easy to get wrong.