Why Cost Per Square Foot Is the Wrong Way to Compare Custom Home Builders
Quick answer: Cost per square foot looks like an easy way to compare custom home builders, but two quotes with the same number can describe very different houses. Builders include different items, measure space differently and treat lot work, allowances and finishes in their own ways. Compare builders on the same plan, the same written specifications and a line-item budget instead.
It is the first question almost every family asks a custom builder in Suwanee: what do you charge per square foot? It is a fair question, but the answer hides more than it reveals. Here are seven mistakes to avoid when you compare builders on that one number, and a better way to compare them.
Why is cost per square foot misleading for custom homes?
Cost per square foot divides a total price by a size, but neither the price nor the size is defined the same way from one builder to the next. A production builder repeating the same plan in one community can quote a dependable average. A custom home is a one-off design on a one-off lot, so the average hides almost everything that makes it cost what it does.
1. Assuming every quote includes the same things
Two builders can quote what looks like the same number and be pricing different jobs. One may include the driveway, landscaping, appliances, permits and design fees; another may leave some of them out. Before you compare, ask every builder for a written list of what is included and what is not. The National Association of Home Builders suggests asking, for example, whether landscaping is part of the price and whether there are extra fees.
2. Not asking how the square footage is measured
Square footage is not one number. Some builders count only finished, heated living space; others count the total under roof, including the garage, porches and decks. A bigger denominator makes the per-foot figure look smaller without changing the price of the house at all. Ask each builder exactly which spaces their figure includes.
3. Ignoring the national measuring standard
There is a national standard for measuring homes, but builders are not required to quote by it. ANSI Z765 is a voluntary standard for calculating above-grade and below-grade square footage in single-family homes, according to Home Innovation Research Labs. Fannie Mae has required appraisers to follow ANSI Z765-2021 on most single-family appraisals since April 1, 2022 (Fannie Mae fact sheet). Under that standard, any floor that is partly below ground is treated as a basement, and two-story foyers and other openings to the floor below are left out of the living area. That means the size your appraiser reports may not match the size a builder used to quote.
4. Forgetting that a basement changes the math
On a sloped north Georgia lot, a finished walk-out basement can be some of the best space in the house, but appraisals usually report it separately from above-grade living area. The National Association of Realtors notes that below-grade spaces, garages, porches and unfinished areas generally do not count toward gross living area, even when they add value. Ask each builder whether basement space is in their per-foot figure, and whether it is finished or unfinished.
5. Leaving out the lot and site work
The land can change the cost of building more than almost anything inside the house. Clearing, grading, retaining walls, rock, a long driveway, septic or a well, utility connections and erosion control all depend on the lot, not the floor plan. A per-square-foot figure quoted before a builder has seen your lot cannot account for any of it.
6. Comparing quotes with different allowances
An allowance is a placeholder amount for items you have not chosen yet, such as cabinets, lighting, flooring or plumbing fixtures. One builder may set realistic allowances based on what you have said you want; another may set them low to make the starting number look better. When your real selections come in above the allowance, you pay the difference. Ask what each allowance assumes, and compare them line by line.
7. Treating every plan shape and finish level as equal
A simple rectangle with one roofline costs less per foot than a home with many corners, roof valleys, vaulted ceilings and large windows. Kitchens and baths cost far more to build than bedrooms, so a plan with more of them costs more per foot at the same size. Finish level matters too: stock cabinets and laminate are a different job from custom cabinetry and stone. A per-foot figure flattens all of that.
The wrong way vs. the right way to compare builders
Put every builder on the same footing, then compare line by line.
| The wrong way | The right way |
|---|---|
| Comparing per-square-foot figures | Asking every builder to price the same plan and specification |
| Comparing total square footage | Comparing heated living area, with garage, porches and basement listed separately |
| Taking "everything included" at its word | Getting a written list of inclusions and exclusions |
| Picking the lowest starting number | Asking what each allowance assumes you will choose |
| Accepting an estimate before anyone sees the land | Having each builder walk the lot and price its site work |
| Leaving finish level "to be decided" | Getting a written specification of brands, grades and materials |
| Comparing price alone | Asking whether the contract is fixed price or cost-plus, and how change orders are priced |
Why does the contract type matter more than the per-foot number?
The contract decides how much the final price can move, and a per-foot figure says nothing about it. Under a fixed-price contract, the builder commits to a price for a defined scope. Under a cost-plus contract, you pay actual costs plus a fee. Either can work well, but you need to know which you are signing and how changes and allowance overages are handled. NAHB also advises getting a written estimate and a detailed contract before any work begins (NAHB).
Advantages of fixed-price and cost-plus contracts
Advantages of a fixed-price contract
- You know the price for the defined scope before construction starts.
- Budgeting and loan planning are simpler.
- The builder carries the risk if the defined work costs more than expected.
- Changes are handled through written change orders, so it is clear what moved the price.
Advantages of a cost-plus contract
- You see what the work actually costs, line by line.
- The work can start before every selection is final.
- If parts of the build cost less than expected, you benefit.
- It can suit lots or designs with real unknowns, where a fixed price would need a large cushion.
When to do what
- Before you ask for quotes: settle on one plan and a written specification to give every builder.
- Before you compare numbers: have each builder walk your lot and price its site work.
- When the quotes come in: line up inclusions, exclusions and allowances side by side.
- Before you sign: confirm the contract type, how change orders are priced and what happens when selections run over an allowance.
How Ironwood talks about cost
Ironwood Construction Group is a family-owned builder, founded in 2008 by Clay Ortiz, who builds with his son Levi. We build custom homes and remodels in Suwanee, Sugar Hill and the rest of north Gwinnett and Hall County, and we do not build spec homes. Because every home starts with a family and a lot, we would rather walk through what drives the cost of your build than quote a number that hides it. Our free floor plans are a good place to start the conversation. Bring a plan you like and talk to the builder.
Frequently asked questions about cost per square foot
Is cost per square foot ever useful?
It can be a rough starting point for comparing homes built from the same plan in the same community. For custom homes on different lots with different finishes, it is too blunt to compare builders fairly.
Why do two builders quote such different per-foot numbers?
They are usually pricing different inclusions, measurements, allowances and lot assumptions. A line-by-line comparison usually explains the gap.
Does the garage count in square footage?
It depends on who is measuring. Appraisal standards generally leave garages out of gross living area, but some builders include them in a total under-roof figure. Always ask.
Why do smaller custom homes often cost more per square foot?
Kitchens, baths, mechanical systems and site work cost about the same whether the house is large or small. Spread over fewer square feet, those fixed costs raise the per-foot figure.
What should I ask a builder instead of the price per square foot?
Ask them to price the same plan and specification you are giving every other builder, with a list of inclusions and exclusions, realistic allowances and site work for your lot. Then compare the quotes line by line.
Sources
- Fannie Mae, "ANSI Measurement Standard Fact Sheet," updated March 31, 2022
- Home Innovation Research Labs, "Square Footage Method Standard FAQ" (ANSI Z765), homeinnovation.com
- National Association of Realtors, "Why Do Square Footage Disputes Arise?", Realtor Magazine, May 2021
- National Association of Home Builders, "Questions to Ask Your Home Builder," nahb.org consumer resources
- National Association of Home Builders, "How to Choose a Home Builder According to the Experts," nahb.org consumer resources