The True Cost of Underbidding: What One Missed Detail Can Cost You

Gage Jaeger
Jul 28
6 min read

Updated: Aug 6

Ask anyone who's been in spray foam for a while, and they’ve got a story about the job that went sideways because of one small oversight. Maybe it looked good on paper, maybe the quote got rushed out the door, or maybe the client seemed easy — but by the end of it, there was barely any money left to show for the work.

Underbidding happens. Sometimes it's a mistake. Sometimes it's a strategy. Either way, it's a habit that can quietly eat away at your profits and burn out your crew. Let’s talk about why it happens, what it really costs, and how you can avoid it.

Where Most Underbids Begin

The biggest estimating issues usually start small. A missed gable. A roof pitch that wasn’t factored in. An assumption about foam thickness that turns out to be wrong. Most of these aren’t huge errors — they’re just the kind of things that happen when you’re juggling multiple quotes, fielding phone calls, and trying to get numbers back to a client quickly.

Maybe you used measurements that the builder gave you without double-checking. Or maybe the job called for three inches on the roof deck and you wrote it up for two without thinking twice. Those kinds of slip-ups are easy to make, especially if you're quoting off memory or trying to be the first to reply.

Even more subtle is forgetting to adjust for the substrate. Spraying clean OSB is a different game than hitting corrugated steel. The surface area expands, waste increases, and if you're not accounting for that in your board foot calculations, you’re going to fall short. And every time you forget to build in a buffer for overspray, substrate loss, or just the unpredictable nature of real-world jobs — you’re the one covering the difference.

What That One Missed Detail Can Cost You

Let’s say you’re quoting a straightforward metal building. Nothing fancy — just four walls and a roof. The client says it’s 40 by 60, ten feet tall, and wants two inches of closed-cell foam across everything.

You run the numbers:That’s roughly 4,000 square feet of wall surface. You calculate the board feet — 4,000 × 2 = 8,000 BF — maybe add a little safety margin, and quote the job.

But here’s the catch: you didn’t account for the corrugated metal.

Steel buildings almost always have ribbed or fluted panels — and those little ridges add a surprising amount of surface area. Depending on the depth and spacing of the corrugation, you’re looking at anywhere from 10% to 15% more surface to cover.

If your 4,000 square feet of “flat” wall is actually closer to 4,600 square feet once you trace every peak and valley, that’s an extra 1,200 board feet of foam on a two-inch pass. If you’re using a closed-cell foam with a yield of 4,000 BF per set, you’re now burning through nearly one-third of a set that you didn’t plan for — just to cover surface area you didn’t account for.

And that’s assuming everything else goes perfectly — no overspray, no waste, no bad batch, and no weather issues.

This is exactly why including a buffer — even on “simple” jobs — isn’t just a good habit, it’s a necessity. Foam loss happens. Spray patterns drift. Substrate temperatures can drop yield without warning. The building might have extra bracing or odd penetrations you didn’t catch at first glance. If you’re not building in at least a 10–15% contingency, then you’re the one covering the difference.

Here’s a simple baseline to work from:

Flat, clean walls? Buffer 10%.
Corrugated or ribbed metal? Bump that to 15–18%.
Oddball structures with obstructions or complex shapes? Go 20% or more.

Some contractors treat the buffer like it’s padding — something they can “eat” to be more competitive on price. But the truth is, it’s the only thing keeping your margin safe when the job turns unpredictable.

Foambid includes this logic automatically — and gives you the ability to adjust your buffer based on structure type, substrate, and even labor conditions. The goal isn’t to upsell the client — it’s to make sure you’re not paying for the privilege of doing the job.

Because that one missed detail? It’s almost never a dealbreaker on its own. But it’s almost always the reason the job didn’t pay what it should’ve.

The Race to the Bottom — Why It’s a Bad Game to Play

Then there’s the kind of underbidding that isn’t accidental — it’s intentional. Some contractors knowingly bid low just to win the job. They look at the market, see who’s working in the area, and drop their number by a few thousand dollars to grab the client first. It’s not about what the job actually costs — it’s about making sure someone else doesn’t get it.

That tactic might fill up the calendar for a while, but long term, it’s poison. You’ll see it talked about all the time in places like the Spray Foam World Wide Facebook group, where seasoned members refer to it as “racing to the bottom.”

And that’s exactly what it is — a race. Not toward growth, not toward sustainability, but toward lower margins, higher stress, and poorer results. Because when you start winning bids on price alone, you trap yourself. Now the client expects that low number every time. You start cutting corners to preserve any profit. The quality suffers. Your crew feels the pressure. Before you know it, you’re running harder just to stay afloat.

What’s worse is that it drags everyone else with you. When one contractor starts slashing prices, others feel forced to match. But no one really benefits. It cheapens the trade and turns a skilled, technical craft into a price war. And in the end, the only person who wins is the client — temporarily — while the contractors are stuck footing the bill.

Successful businesses aren’t built on being the cheapest. They’re built on being consistent, profitable, and trusted. You don’t have to undercut anyone to stand out. You just have to bid accurately, do solid work, and back it up with professionalism.

More Than Just Money

The dollar loss is one thing. But underbidding does damage in quieter ways too. You start chasing work instead of choosing it. You feel stretched, behind, and stressed out trying to finish jobs that don’t even pay well. That kind of pressure wears on you — and your team.

Worse, it sets a precedent. If a client gets a cheap price from you once, they’ll expect it every time. If you try to adjust your rates later, they might push back or walk away, assuming you’re being greedy when really, you're just trying to charge what the job’s actually worth.

There’s also the opportunity cost. While you're spending three days on a job that barely breaks even, you might miss out on a better one — something that would’ve paid fairly, run smoothly, and left you with enough margin to breathe.

A Better Way to Bid

There’s a difference between being competitive and being careless. Smart bidding means taking the time to estimate properly, using real math, and leaning on tools that help you stay accurate.

Your estimate should reflect:

The full square footage, including gables and roof slopes
The correct foam thickness, yield, and waste factors
The complexity of the substrate
The labor you’ll realistically need to finish strong

You don’t need to pad your numbers. But you do need to cover your costs — and protect your margin — so you can keep growing. That’s why we built Foambid with detailed geometry, customizable defaults, and structure-specific logic. It’s not about overcharging. It’s about charging correctly.

You Deserve to Profit From Every Job

Nobody goes into this line of work hoping to just break even. You didn’t buy your rig, build your crew, and put in the hours to end up barely covering materials. And yet, that’s exactly what underbidding leads to — job after job where you're working just to stay even.

It doesn’t have to be that way. With the right estimating process, you can quote with confidence, know your numbers are solid, and walk away from every job knowing you did it right.

So double-check those measurements. Slow down on the quote. Use a system that does the math for you. Because one missed detail can cost you thousands — but dialing in your bids can earn you tens of thousands over time.