How to price a spray foam job

Start with board feet, not square feet

A board foot is one square foot of foam one inch thick. It is the only unit that connects what the customer sees (a wall, an attic, a crawl space) to what you pay for (a set of A and B drums). A 1,200 square foot attic floor at 10 inches of open cell is 12,000 board feet. The same attic in a 2x6 wall at 3 inches of closed cell is 3,600 board feet. Price the square foot without doing this step and two jobs that look alike on the walk can cost you very different money.

So the first line of every spray foam estimate is really three numbers: the area, the thickness, and the product. Area times thickness in inches is your board feet. Everything else hangs off that.

Use the yield you actually get, not the one on the drum

Your supplier quotes a theoretical yield per set. You will never hit it. Substrate temperature, drum temperature, hose length, overspray, trimming, and the last few gallons that never come out of the drum all eat into it. Most contractors who track it land somewhere between 70 and 85 percent of the number on the data sheet, and the only way to know yours is to count: board feet sprayed divided by sets used, across a few jobs.

Once you have a real yield, material cost per board foot is simple: set price divided by real board feet per set. If a set of open cell runs you $2,200 and you get 12,000 board feet out of it in practice, you are at about 18 cents a board foot. If closed cell is $3,000 a set and you get 3,600 board feet, you are at about 83 cents. Those are example numbers; put yours in. The point is that the pennies per board foot are what you multiply by thousands, so a 10 percent yield mistake is a real dollar mistake on every job.

The rig costs money whether it sprays or not

Fuel for the truck and the generator, compressor hours, gun rebuilds, transfer pumps, hose, the heater, the trailer tires, and the day the proportioner goes down. Add it up over a year and divide by the days you actually spray, and you get a rig cost per spray day. It is usually a bigger number than people expect, and it belongs in the price of every job as a flat daily line, not hidden in the markup.

Consumables go on top: plastic and tape for masking, suits, cartridges, mask filters, spray tips, cleaning solvent. A small job can burn as much masking as a big one, which is one reason a per-square-foot price alone punishes you on little jobs.

Labor, overhead, then margin

Labor is crew hours times what an hour really costs you with payroll taxes and insurance, from the time the truck leaves the shop to the time it is back and cleaned. Prep and masking are labor. The drive is labor. The call back to trim a bulge is labor. Overhead is the shop, the insurance policies, the phone, the software, the truck payment, spread across the jobs you do in a year. Only after material, rig, consumables, labor and overhead are all in do you add the margin you want to keep, and that margin is yours to decide, not the market's.

Now turn the total back into the unit the customer expects. Divide the job total by the square feet and you have your price per square foot at that thickness, which is the number that goes on the estimate. Working backward like this means the per-square-foot price is the output of your costs, not a guess at what the other guy charges.

A worked example

Take that 1,200 square foot attic floor at 10 inches of open cell: 12,000 board feet. At 18 cents real material cost that is $2,160 in foam. One spray day for the rig at, say, $350. Consumables $150. Two people for nine hours including drive and cleanup at a loaded $38 an hour is $684. Overhead at 15 percent of those costs adds about $500. That puts the job at roughly $3,850 before you have made a dollar. A 25 percent margin on top lands it near $4,800, which is $4.00 a square foot at 10 inches. Change the thickness to 8 inches and the same math drops the price. Change the product to closed cell and it climbs fast, because the material line more than quadruples while the labor barely moves.

Those are illustration numbers, not a price list. The method is the point: board feet, real yield, rig day, consumables, labor, overhead, margin, then back to a per-foot number you can defend.

Set a minimum, and write the thickness on the estimate

Two habits save foam contractors from the two most common ways to lose money. The first is a minimum job charge, because a rim joist in a crawl space costs you a full setup, a full cleanup and half a day of masking for a few hundred board feet. The second is stating the product and the thickness in inches on every line, right next to the square feet. It is what you are actually selling, it is what the inspector will check, and it is what protects you when the customer says they thought they were getting more.

Put the R-value next to it if the job is driven by code. Open cell and closed cell are not interchangeable per inch, and an estimate that says "spray foam the attic" without thickness or product is an invitation to a change order you cannot bill.

Price it on the walk, not at the kitchen table at 9 PM

Once your per-board-foot costs are in a price book, the number is just area times thickness times rate, and that is a job for the phone in your pocket, not a spreadsheet after dinner. Say the rooms and the thickness as you walk the house, snap the attic, and the estimate is itemized and priced before you are back in the truck. The customer gets it while you are still the contractor who was just there, which is when it gets signed.

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