Why Home Building Bids Vary So Much

Bids differ because of what is in them, not because of what things cost. Every builder in Ada and Canyon County buys concrete, lumber, trusses and labor at roughly the same prices. There is no secret supplier. So when two proposals on identical drawings arrive $150,000 apart, the explanation is almost always in the scope, the allowances, the site assumptions, or the fee, and it is usually findable in an afternoon. This article is part of our guide to choosing a home builder in Boise, and it separates the differences that are legitimate from the ones that are not.

You can build a $150,000 gap on the same 2,400 square foot plan out of two assumptions, without either builder quoting a single item differently.

Take a rural parcel outside Kuna. One builder walks it, sees no city water or sewer at the road, and carries a well, a septic system designed through Central District Health, and an access drive: $80,000 to $150,000. The other builder prices the house and notes site work as excluded, or carries a serviced-lot allowance of $25,000 to $50,000 because that is what most of their projects need. That single difference in reading the lot is worth up to $125,000.

Now add design and engineering. One bid carries it at 5 to 12 percent of construction cost, commonly $9,000 to $35,000. The other bills it separately. The gap is now larger than the entire finish budget most people argue about, and the two builders have not disagreed about the price of anything. Published planning bands are wide for the same reason: most Treasure Valley custom homes fall between $250 and $400 per finished square foot excluding land, which on 2,400 square feet is $600,000 to $960,000, and the spread inside that band is mostly scope. Our Boise home building cost guide breaks the band down further.

Allowances are the most powerful lever in a bid and the least visible. An allowance is a placeholder for something not yet selected: flooring, cabinetry, tile, lighting, plumbing fixtures, exterior stone. Nothing in a proposal makes it obvious whether the number is realistic, and the total at the bottom of the page looks equally authoritative either way.

Set the allowances at what things actually cost at Boise suppliers and the bid is a forecast. Set them low and the bid is a marketing document. The homeowner picks the same finishes in both cases and pays roughly the same amount in the end; the difference is whether they knew in month one or found out in month six. This is why we set allowances at what things cost here rather than at a number that wins the bid, and why the useful question is not what the allowance is but how it was arrived at.

Two builders can price the same lot completely differently because only one of them went and looked at it. Site work is the largest single variable in residential construction and the one most often assumed rather than investigated.

The questions that move the number are whether the soil requires over-excavation and structural fill, whether the lot needs retaining, how far the utilities actually are from the building envelope, whether a septic system is required and what the soil percolation supports, and on foothills sites whether a geotechnical report will drive a deeper or engineered foundation. A flat, serviced lot in Meridian or Nampa and a sloped foothills parcel above Boise are different construction problems even with the identical house on top. Foothills sites with steep grade and high detail regularly run above $450 per finished square foot for that reason. The article on what a well and septic system costs in Idaho covers the rural end of this.

Generic specification language is where five-figure differences hide in plain sight. A bid that says granite countertops has told you almost nothing. Granite spans remnant material at a local yard through to a slab selected and shipped for its pattern, and the fabrication, edge detail, waterfall ends and seam placement can double the installed cost of the same stone.

The same is true of every generic word in a specification. Hardwood flooring covers engineered plank at builder grade and site-finished white oak. Tile covers a field tile at a few dollars a square foot and a hand-set pattern that takes a setter three days. Windows covers a vinyl unit and a clad wood unit with a warm-edge package, and on a house with a large glazed elevation that single line can move the total by tens of thousands. When two bids use the same word, assume they mean different things until someone shows you a product name. Our guide to choosing finishes for a new home goes through where the money actually goes.

The soft costs of building a house are large enough to matter and are treated inconsistently across bids. Design and engineering commonly run 5 to 12 percent of construction cost, about $9,000 to $35,000. Permit and plan review fees, impact fees and utility connection fees are separate again, and vary by jurisdiction across the eight Treasure Valley cities.

Some builders carry all of it inside a single number. Some carry none of it and expect you to pay it directly. Both are defensible. What is not defensible is a bid that stays quiet about which approach it took, because the reader assumes the more favorable interpretation every time. When you find this difference, do not adjust for it in your head. Write the number down and add it to the bid that excluded it, which is the core of how to compare home builder bids.

This is a legitimate difference and it is smaller than people expect. A builder's overhead pays for the office, the estimator, the superintendent, the warranty response, insurance, and the time spent on projects that never sign. Margin is the profit on top. Together they are a percentage of the job, and the spread between a lean operation and a well-staffed one is usually single digits, not six figures.

What the higher number tends to buy is capacity. A superintendent running three houses is on your site most mornings; one running eight is on your site when something has already gone wrong. Trade partners who get paid within a week show up when scheduled. A warranty department that exists answers in month eight. None of that appears in a bid document, which is precisely why the cheaper number looks like the same product. Ask each builder how many active projects their superintendent carries and you will learn more about the fee difference than any line item will tell you.

A shorter projected schedule is not free, and a longer one is not laziness. Time costs money in construction: general conditions, supervision, temporary power, portable facilities, equipment rental, and financing all run per month, so a nine month build and a fourteen month build have genuinely different overhead loads.

A builder assuming a compressed schedule prices less general conditions. If that assumption is realistic because they control their trades and have built the plan before, the saving is real. If it is optimistic because it assumes no plan review comments, no winter concrete delays and no long-lead window package, the saving evaporates and reappears as either a cost claim or a builder quietly losing money on your house, which is not the safe outcome it sounds like. Ask what schedule the bid assumes and what happens to the price if it runs longer.

Some low bids are low on purpose, and the business model depends on you being unable to leave. Once your foundation is in the ground and you have paid two draws, switching builders means a new contract, a new mobilization, an argument about the work in place, and months of delay. Practically nobody does it. A builder who knows that can price below cost, win the work, and recover the difference through change orders against a scope loose enough to permit it.

The mechanism requires two ingredients: a low number and a vague document. That is why the tell is not the price by itself but the combination of a price nobody can explain with a change order process nobody will describe. If a builder can tell you exactly why they are lower, in specifics you can verify, the low bid may be entirely genuine. If the explanation is that they run lean and want the work, keep reading the exclusions. This pattern and its relatives are covered in home builder red flags.

There is a version of a low bid that is not dishonest and is still dangerous: the builder simply needs the job. A quiet period, a crew to keep busy, a first project in a new city, and a number gets sharpened until the margin no longer covers the risk.

The problem is what happens in month seven when that project is losing money. The pressure shows up as substitutions you did not ask for, a superintendent reassigned to a profitable job, slow responses, and pressure on draws. In the worst case the builder does not finish. A fee that cannot absorb one bad month is a risk you are carrying whether or not it is written into your contract, which is one reason the structure of the agreement matters. See fixed price versus cost plus for how each structure handles that pressure.

Ask the low bidder to explain the gap in specifics, and listen for whether the answer names things. A legitimate lower price sounds like: we build this plan regularly and our framing labor is fixed on it; our overhead is lower because we run a smaller office; we assumed a serviced lot because we read the plat. Every one of those is checkable.

An illegitimate one sounds like a claim about attitude. We are hungrier. We run lean. We want to earn your business. Those are not explanations, they are sentiments, and none of them will lower the cost of a truss package. When you have the explanations, redo the arithmetic with matched scope and see where the numbers land. If a lower bid survives normalization and the explanation holds up, it is a real advantage and you should take it.

If you are holding two or three numbers that will not reconcile, we will go through them with you line by line, including when the honest conclusion is that someone else has priced your house fairly. You can send them over, or run your plan through the build cost calculator to see which band your project should be landing in before anyone quotes it. For the mechanics of putting proposals on the same footing, read how to compare home builder bids.