How Much Does It Cost to Build a House? A Contractor’s Checklist To Get a Real Number

If you’re asking how much does it cost to build a house, my honest reply is: a square-foot number will not save you. I’ve spent most of my career in the part of construction no one plans for—the phone calls that happen after a budget falls apart and there’s a deadline in the window. In March 2024, I was on a call with a homeowner 10 days before a construction loan closing. His bid was missing the entire roof insulation package. Not a small line item. The entire package.

That’s why I don’t start with averages. I start with a checklist. When someone asks me what a house really costs, this is the list I use. It’s not the prettiest way to budget, but it works.

The Budget Checklist I Use Before I Give Any Number

1. Put Your Systems in Writing Before You Put a Price on Them

A budget estimate needs a written scope. Otherwise, “1,800 square feet” can mean the heated floor area in one bid and the footprint of the house in another. I saw that exact difference turn into an $80,000 gap on a 2024 custom house. That isn’t because one contractor was greedy. It’s because the comparison was set up wrong.

Write down the conditioned space, the unconditioned space, and the porch or garage scope first. Then list the exterior enclosure method. The enclosure drives most of your cost, but most people spec kitchens and bathrooms before roof systems. Do not do that.

2. Treat the Roof as a System, Not As a Material

On a low-slope roof, TPO is usually my first recommendation. But there is a difference between saying “TPO roof” and pricing a Johns Manville TPO roofing system. The product name gets all the attention; the system does the water shedding.

A TPO budget that is missing an insulation layer, cover board, fasteners, edge metal, or compatible flashing is not a TPO budget. It’s the opening scene of a change order. If you’re comparing bids, ask each roofer to list every component in the assembly. Ask where the membrane will be mechanically attached. Ask how penetrations are flashed. Ask what the warranty actually covers once the system is installed.

I know it’s boring. The roof is where the money sleeps, though.

3. Read Johns Manville R-6 Foam Board Insulation Reviews With a Critical Eye

Homeowners do a lot of research, and then they send me Johns Manville R-6 foam board insulation reviews. That’s fine. Reviews tell you whether a box arrived damaged. They rarely tell you whether the board is part of an approved roof assembly or where the dew point lands inside the wall assembly.

The conventional wisdom says more insulation is always better. In practice, the right insulation is the one that fits the rest of the system. R-6 per inch is a good thermal number, but it only describes the material in a lab. If you install that foam on the wrong side of the assembly, you can create problems that no amount of R-value can fix. Use reviews to learn about field issues like shipping damage or edge cracking. Then use a manufacturer data sheet for the technical decisions.

If you’re hiring an installer, ask which foam board they’d use and why. Listen for specifics—the facer, the fastener pattern, the approved adhesive. If the answer is just “we always use this,” slow down.

4. Separate the Stone Material From the Labor in Your Exterior Budget

Stone is one of the easiest places for a budget to hide a mistake. There is a material cost, and there is a labor cost. Those two are often quoted by different trades. When the bid says “stone,” ask directly: Is this manufactured stone veneer, or is this natural stone that will be set piece by piece? Is there hand and stone work around the corners, windows, and arches?

I’m not saying manufactured stone is bad. I am saying it’s a different product with a different labor rate. Hand and stone installation requires masons who can cut and lay material. If someone substitutes it later, your budget changes. Put the exact term in the contract. “Stone veneer” and “hand and stone work” are not interchangeable.

5. Do Not Let the Small Metal Pieces Sneak Past You

I still kick myself for missing the skull cap on an early budget. The skull cap is the metal cap on top of a chimney chase or flue—some call it a chimney cap, some call it a chase cover, and some old-timers call it a skull cap. It’s an easy detail to overlook because it sits out of sight. But when it is missing, water runs down the chase and the ceiling stain appears a month after move-in.

On a recent project, we added a flashing line for the skull cap and the roof penetration boots. The material cost was about $360. If I had to order that after the roof crew left, the service call alone would have been higher. Check your estimate for flashing, chase caps, edge metal, and termination bars. These items are small on paper and expensive in insurance claims.

6. Add a Risk Line Even When You Think You Don’t Need One

Every budget gets a risk reserve, including the ones where clients insist there’s no room. A reasonable minimum is a separate line around 10 percent. If no surprises show up, that money can go into a finish upgrade. If surprises do show up, you have a plan instead of a panicked call.

Contingency sounds like a cushion for the contractor. It’s not. It’s the cost of the soil beneath the slab, the rain during framing, and the code comment that arrives after rough-in. Budget for the world to be slightly less cooperative than your spreadsheet.

7. Ask What Is Not Included Before You Ask the Price

This is the question that reveals the most about an estimate. When a vendor lists all fees upfront, even if the total looks higher, that vendor usually costs less by the end. The surprise is rarely in the line items you compare. It’s in the line items that were left out to make the number look better.

If someone answers “nothing is missing” without showing you a detailed scope, don’t trust it. Good estimators know their exclusions. They can tell you exactly where the allowance stops, what happens if the groundwater is problematic, and which components are not part of the labor rate.

The Bottom Line

So here is my honest answer to how much does it cost to build a house. It costs exactly what the detailed scope says it costs, plus the risk reserve and the line items nobody pointed out. From late 2024 through early 2025, the reasonable bids I reviewed for custom slab-built houses ranged from about $185 per square foot in lower-cost states to $330 per square foot for houses with real masonry details. In coastal or high-cost metro areas, the same specifications can easily pass $400 per square foot. Use those numbers as a smell test, not a specification.

Start with the roof, walls, insulation, foundation, and water details. Make those explicit. Then let the finishes fit what is left. That order has saved more construction budgets than any discount I have ever negotiated. Check the current code requirements for your climate zone and talk to a licensed local contractor before you commit to anything.