Who Should Own the Estimate: Owner, Architect, or GC?

You should usually own the estimate, or at least commission an independent one. Architects' contracts typically limit them to conceptual estimates and disclaim any guarantee about bids, GCs have a stake in the number, and GAO's cost guide treats reconciling a point estimate with an independent cost estimate as a best practice.

Who owns the construction estimate matters because the owner carries the financial risk when the numbers are wrong. This article, part of the construction cost estimating series, explains what each party does, where incentives conflict and how an independent estimate fits in.

Who owns the construction estimate, and what does each party provide?

Three parties produce cost numbers. They are not interchangeable.

A GMP is a ceiling under which the construction manager's fee plus the Cost of the Work shall not exceed an agreed amount, per AIA A133. The estimate behind it is a negotiating document as well as a technical one.

Is the architect responsible for the construction cost estimate?

The architect is responsible for designing within the owner's stated program and budget in good faith. The architect is not typically responsible for guaranteeing that bids match the estimate.

Commentary from Zweig Group on AIA B101 says the architect's cost evaluations are professional judgment, the architect does not warrant that bids will match the budget or estimate, and basic services are conceptual estimates by area or volume. Detailed estimating is a supplemental service. The commentary is secondary, so verify the language in your own agreement. Engineering agreements such as EJCDC forms contain similar disclaimers.

For owners, the implication is plain. If you assume the architect's number is a guaranteed price, you are holding a risk you did not agree to hold.

Why not leave the estimate to the GC alone?

A GC is a skilled estimator with current market pricing, and early GC input is valuable. The concern is incentive, not competence.

In a lump-sum bid, a GC prices to win. In a GMP contract, the GC's pre-award estimate can shape the ceiling it later has to meet, and a conservative number protects the GC. This tension is a reasoned inference rather than something a standard document states, but it is a standard reason owners want a second opinion. A GC may also price to the scope as it understands it, not to the scope you intended.

None of this means distrust. It means you want a reference number from a party whose compensation does not depend on the contract price. The GC markup on subcontractor bids article shows how much of a GC price is structured judgment rather than fixed cost.

What is an independent cost estimate and why does GAO recommend one?

An independent cost estimate is a separate estimate prepared by someone outside the team that produced the primary estimate, usually from the same documents. The reconciliation is the valuable part: the two estimators explain where and why they differ.

The U.S. Government Accountability Office's Cost Estimating and Assessment Guide (GAO-20-195G) says best practice includes comparing the point estimate to a reconciled independent cost estimate. It also notes that differing technical baselines make comparison hard, which is why both estimators should work from the same drawing set and written scope. The GAO cost guide page describes the approach.

ASTM E1804 supports the practice from the format side: summarizing estimates in MasterFormat or UNIFORMAT eases comparison with the GC's format, and reconciliation can be needed at any design phase.

At which milestones should an owner get an independent estimate?

A solicitation from the City of Greenville, NC provides a concrete example of an owner-side schedule: an independent estimate at 100% schematic design, 100% design development, 60% construction documents and 100% construction documents, with line-by-line reconciliation to the designer's estimate. The document dates to around 2015, so use it as a pattern rather than a current price.

The how estimates change article explains why numbers move between these points.

How does reconciliation work?

Reconciliation is a structured comparison, not an argument about who is right.

1. Align the baseline. Both estimators use the same drawing set, date and written scope.
2. Format identically. Summarize both in MasterFormat divisions or UNIFORMAT elements.
3. Rank differences by dollar size. Start with the largest line variances.
4. Classify each. Quantity difference, unit-price difference, scope gap, or assumption (for example, escalation, phasing).
5. Resolve and document. Agree on a corrected number or flag the item as a risk with a named owner.

Illustrative example: the designer's estimate for a building is $18,200,000 and the independent estimate is $19,400,000, a $1,200,000 gap. Reconciliation shows $700,000 from a mechanical system the designer's estimate carried at a lower unit price, $350,000 from missing site retaining walls, and $150,000 from different escalation assumptions. Two of the three are actionable scope and pricing questions the owner can resolve before bidding. The numbers are assumptions for arithmetic.

What should you put in the scope for an independent estimator?

A vague engagement produces a vague estimate. Specify these items in the request for proposal:

• the drawing sets and dates to be priced, and the milestones listed above;
• the format required (CSI MasterFormat divisions or UNIFORMAT elements), so comparisons are direct;
• whether the estimator will measure quantities independently or only review the other party's;
• the escalation method, naming the index and the assumed construction midpoint;
• the reconciliation meeting and written reconciliation report for each milestone;
• the treatment of allowances, alternates and contingency.

Interview two or three firms. Ask how they handle a design that is incomplete, what they do when quantities cannot be measured from the drawings, and how recently they priced similar buildings in your market. Ask for a sample reconciliation report with client details removed. A firm that cannot show how it explains variances will not give you the clarity you are paying for.

Finally, decide who receives the estimate. Many owners send it to the owner's representative, who reconciles it with the designer and the GC, so the independent number stays independent.

What should the owner own, regardless of who prepares the number?

Even with an independent estimator, certain decisions stay with you.

• The budget. Only the owner decides how much to commit, including soft costs, financing and contingency. See estimate vs budget vs contract value.
• The risk appetite. How much contingency and how many allowances you will accept.
• The scope. Changes to program drive more cost movement than any estimating method.
• The reconciliation record. Keep every estimate, the drawing set it priced and the explanation of differences.

One caveat: independent estimates add a fee and take time, and for a small, simple project a careful GC estimate with a few trade quotes may be enough. Costs vary by market, so the decision should reflect your project's size and risk.