Calculators · Estimating · Class 5, AACE 56R-08

Construction cost

An order-of-magnitude budget with a trade breakdown, from building type, floor area, storeys and quality. US cost indices in US dollars; the method also works for a first Canadian number with a local index.

Free. No sign-up. Not sealed engineering. By Ali Mazloum, P.Eng.

Inputs

Use an area between 500 and 5,000,000 sq ft.
Defaults: a 25,000 sq ft Class B office, two storeys, standard quality, Texas.
Estimated total, midpoint –
Low–
High–
Per sq ft–
Estimate class–

Class 5 conceptual estimate in US dollars from regional indices. Site, soil, market and design complexity are not in it. Educational use; not a bid.

Trade breakdown

Midpoint figures, US dollars
Trade$ per sq ftTotal
Method  Each of nine trades has a low, mid and high cost per square foot by building type. Each is multiplied by the quality factor (economy 0.80 to luxury 1.65), a storey factor weighted by trade, and the state index, then by the floor area. The three totals give the range; the midpoint is the headline.

What a Class 5 number is for

Five minutes

A Class 5 estimate answers one question: is this project in the right order of magnitude for the budget? It is the number for a feasibility study, a screening meeting or a first budget authorization, built from the little that is known at concept stage.

The nine trades

Sitework and utilities; structure (concrete, masonry, steel); envelope (roofing, cladding, windows); interior finishes (drywall, flooring, paint, doors); mechanical; plumbing; electrical; fire protection; and general conditions with overhead and profit. Each is adjusted on its own for building type, quality, storeys and location, so the split is as useful as the total.

Reading the range

For buildings, AACE International Recommended Practice 56R-08 puts Class 5 accuracy at -20 to -30 % on the low side and +30 to +50 % on the high side. The low and high figures here are the trade ranges added up; the midpoint is a reasonable planning number. As the design develops, Class 3 and then Class 1 estimates by a professional estimator replace it.

Canadian projects

The indices are US-based and the figures are in US dollars. The trade structure is the same on a Canadian job, so pick a state with a similar market, convert, and treat the result as the starting point for a proper takeoff.

FAQ

Straight answers
What is a Class 5 estimate?

The earliest and least detailed level of cost estimate, as defined for building and general construction by AACE International Recommended Practice 56R-08. It is built from concept-level information and is expected to land between -20 to -30 % on the low side and +30 to +50 % on the high side of the final number. It is for feasibility, screening and a first budget.

How are location factors calculated?

From regional cost indices of the RSMeans kind, which track labour rates, material and equipment costs by state. 1.00 is the US average; New York sits near 1.30 and Mississippi near 0.82.

Why do costs rise with more storeys?

Taller buildings need heavier structure, longer mechanical and electrical distribution, elevators and cranes. The storey factor is weighted by trade: structure, mechanical and electrical feel it most, sitework and general conditions least.

Can I use this for Canadian projects?

The data is US-based and in US dollars. The trade split is similar in Canada, so pick a state whose market resembles yours and adjust for exchange and local conditions. Provincial factors are on the list for a future version.

How accurate is it?

Expect roughly -30 % to +50 % against the final cost. Soil, site, design complexity, market conditions and supply chains all move the number. Engage an estimator for anything you will commit money to.

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