Almost everyone who considers building a custom home asks the question: “How much does it cost per square foot?”
Our response is “what is a square foot?”
As custom builders, we describe the scope of a project by finished and conditioned square feet but also by the details, finishes, complexity and unfinished components that are not typically included in square foot calculations. Examples include porches, garages, unfinished basements or vaulted ceilings.
As building designers we need some idea of cost per square foot so that our new design will better match the project’s budget goals. We use the “Factored Square Foot” method to address cost while still in the design phase.
Imagine a one-story home with 2,000 finished square feet. It is built on a slab or over a crawl space, has 8’ flat ceilings, no garage, no porches, and no unfinished attic. Compare this to another home with the exact same finished square footage. This one has a full walk-out unfinished basement, a timber frame greatroom with exposed timber rafters vaulted to the roofline, a wrap-around porch, an attached two car garage, and a large unfinished attic that’s ready to become a spare bedroom in the future. Both homes have 2,000 square feet finished, but they are very different construction projects, and will have very different costs to build.
Here’s how this tool works for a home we recently designed:
This project has 2,939 finished square feet of conditioned living area but the factored square foot total, or project total, is 4,046. The eventual contract price was $697,000 or just slightly over $170/factored square foot (FSF).
We use fractional multipliers to describe areas that require work, and add to building cost, but that are not traditionally considered finished square feet. The result is the Project Square Feet or Factored Square Feet.
This number is a far better measure of what the house will actually cost than the finished square feet alone.
1.00 - Gross heated square feet measured from the outside of the building
0.50 - Vaulted, cathedral, 2 story space
0.15 - 10’ and taller flat ceilings (we assume 9’ ceilings are standard)
0.20 - Basement area, unfinished, with walk-out
0.50 - Garage, attached or detached
0.30 - Garage in basement
0.20 - Attic area unfinished with stairs up and plywood floor
0.40 - Covered porches or open roof deck over finished areas
0.25 - Open wood decks or hard surface terraces or patios
Remember that this estimating method is not intended to be an exact science. The purpose of this exercise is to try to get a handle on what a project might cost in the design phase. Once the project is designed then S&R will begin a detailed line-by-line estimate to establish the actual cost to build based on the final specifications and details selected by the owners.
Cost Per Factored Square Foot (FSF):
Today we find that a quality custom home designed and built by S&R starts at about $160 per factored square foot and can easily exceed $225 per factored square foot, or more, depending on the features a finishes. The lower cost per factored square foot can be expected when the walk-out basement, or terrace level, has substantial finished area. If there is no finished basement space then expect the starting cost per factored square foot to be around $170.
What to Expect:
What makes one project cost $170 per factored square foot while another is $225? Mostly it’s features, finishes, and specifications, but it can also be design complexity. Simpler houses with fewer corners and uncomplicated roofs usually cost less. Houses with finished basements will cost less per FSF. Larger houses often cost less per square foot than smaller houses because there is an economy of scale in custom building – houses only have one kitchen, one well, one septic system and one driveway regardless of whether they are 1,500 square feet or 5,000 square feet.
From $160 to $185 EXPECT
High quality, low U-factor windows such as Marvin Integrity or Pella Pro-Line.
2x6 wall construction with 3rd party certified Grade 1 insulation and sealing package
Lifetime warranty GAF or equal roof shingles
Poured concrete or superior wall foundations, insulated according to NGBS guidelines
Enhanced foundation waterproofing practices
Engineered floor joists and durable resource efficient sheathing materials
Pre-finished fiber cement siding
Solid wood flooring in main living areas with carpet in bedrooms
Solid wood kitchen cabinets with level 1 granite tops
Solid core hardboard interior doors with Emtek hardware and nicely profiled trim.
14 SEER, or above, heat pump system with zoning designed for comfort and efficiency
Fireplace (wood or gas) with simple but attractive detailing
Exterior porches incorporating pressure treated materials and attractive detailing
From $190 to $220 EXPECT All of the above plus
Enhanced fenestration specifications
Upgraded insulation system using spray-in-place foam and sound isolation
Upgraded roofing specifications
Stucco, stone, brick or cedar shingle siding for portions of the exterior
Upgraded kitchen cabinets countertops and appliances
Solid wood interior doors
Solid wood flooring throughout the house with ceramic tile baths
Upgraded interior trim details
TIMBERPEG construction for portions of the house
Geothermal HVAC system with multiple zones
Fireplaces in multiple locations with upgrade detailing
Upgraded light fixture and plumbing fixture budgets
Upgraded porch and deck detailing using masonry, synthetic or exotic wood decking
Over $225 EXPECT All of the above plus
Even better quality for all specifications and fixtures
More expansive TIMBERPEG post and beam construction with SIPs panels
Radiant floor heating
Metal, cedar shake, or synthetic slate roof
Custom cabinetry and more built-ins
Upgraded appliance, plumbing fixture and lighting fixture allowances
Reclaimed wood flooring
Custom closet interiors
Stucco, stone, brick or cedar shingle siding for the entire exterior
Lighting control or smart-house options
The features and options listed above are just a sampling to give an idea of what to expect in a given price range. In reality, a custom home is a series of trade-offs that maintain the budget. Not many have a budget large enough to get everything on their wish list. By prioritizing the features that are really important, and knowing how much they cost, an owner can pick and choose the features that will make their home special and still reach their budget goals.
Glenn Robertson builds great custom homes. He has a unique ability to assist his client achieve a dream home through accomplished design process, excellent listening skills, effective project management and environmental stewardship.
Fred & Lisa | Nellysford, VA