Cost Estimating

There are basically two ways to estimate costs. You can use square footage and estimate cost per square foot, or you can work up costs from each line item in a construction budget. I did both.

Before I explain each, let me state the obvious. There is no upper limit on what a house can cost. If your house has a $100,000 photovoltaic system in it, that adds $100,000 to the cost of a house without that system. If you put 4000 sq-ft of antique wormy chestnut flooring in the house at $25/sq-ft that will cost $100,000, or about $60,000 more than nice oak flooring, and about $80,000 more than carpeting. Most of this post will relate the basic costs of building a high-quality structure, and not to the expensive jewels you might place in or on that structure.

Caveats: “market conditions” and “sweat equity.”

Estimates Based on Square Footage
Very rough.

Bigger houses will cost less per square foot than smaller houses. These costs are pretty good estimates for a house 3000-5000 square feet.

Custom home 3000-5000 sq-ft built by professionals…pretty much can’t do for less than $100/sq-ft. Plenty of homes are $500/sq-ft. I believe my actual construction costs will come out to about $133/sq-ft not including any design, engineering, or surveying costs (the costs you incur before you break ground). Everything, including all soft costs will probably come out to $150/sq-ft. Unless you are obsessive about cost management, I believe you should assume you will do worse than that, probably closer to $200/sq-ft. Most architects consider $200/sq-ft a low budget for a custom home.

What’s in square footage? All enclosed areas including garage, finished basement, and storage. All covered decks and patios. Mine does not include a large terrace, which has a foundation, pavers, and an awning that is 8 ft. deep.

Bank’s cost worksheet

Some good rules of thumb I used, and which proved to be pretty accurate in 2010:

Windows and patio doors cost $300-400 per unit, where a unit is an individual sheet of glass in a frame.
Interior doors are $200-400 per unit, depending on whether they are painted 6’8″ doors or finished wood 7′ doors.
Appliances: make a list…get quotes from
Framing $7-10/sq-ft of floor space, not including materials.
Foundation $200/cubic-yard of concrete placed.
Excavation: could be as low as $10k for a flat lot with a crawl space or $60k for a steep wooded lot with full basement.
Fire protection (sprinklers): $1-2/sq-ft
Framing materials:
Lighting fixtures: very little to a lot
Lighting controls: $0 to a lot
Tile: $10/sq-ft for installation

RS Means

Means Residential Detailed Costs: Contractor’s Pricing Guide (Contractors Pricing Guide)

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