Spray Foam Insulation — Closed Cell for Attics, Rims and Pole Barns
Where fluff will not do the job — a rim joist, a cathedral ceiling with no room for vents, a pole barn with a sweating roof — closed-cell spray foam seals and insulates in one pass.
JMB Builders does spray foam insulation across the Twin Cities metro: closed-cell foam on rim joists, basement walls, attic roof decks, cathedral ceilings and pole barn walls and roofs. Small jobs are done with our own two-part foam kits; larger areas are sprayed with our spray-foam partner when a rig is needed, with our crew doing the prep, the framing and the finish around it. Priced per project, quoted from your photos within one business day.
- Closed-cell: air seal, vapor control, insulation in one
- Kits for small areas, partner rig for large ones
- Quote from photos in 1 business day
- Licensed MN contractor BC809005
Spray foam is two liquids that mix at the gun and expand into a solid on whatever they hit. Closed-cell foam cures hard, stops air and water vapor, and adds stiffness to what it is sprayed on; it is the one we use almost everywhere in Minnesota because it handles the cold side of a wall without a separate vapor retarder. Open-cell foam is softer and cheaper per inch but lets vapor through, so it needs more thought about where it goes in a cold climate. We will tell you which one fits, and it is usually closed-cell.
Where it earns its cost: the rim joist, where nothing else seals; basement walls, where it goes on the concrete and stays dry; cathedral ceilings and story-and-a-half roof slopes, where there is no room for baffles and batts; and pole barns, where the metal roof and walls sweat every spring and there is no cavity to fill any other way. It is not the answer for a plain flat attic; blown insulation over good air sealing does that job for less.
How we do it depends on the size. Rim joists, small walls and touch-ups are done with our own two-part foam kits. Whole attics, basements and pole barns need a truck-mounted rig with heated hoses, and that is done with our spray-foam partner when a rig is needed. Our crew does everything around the foam: the prep and masking, the framing, the thermal barrier the code requires over foam in living space, and the finish. You deal with us for the whole job.
What you supply
- Photos of the area: the rim, the basement wall, the attic slope or the pole barn from inside
- Rough dimensions of the area or the building
- The space cleared and, for occupied houses, a plan to be out of the house while the foam cures and vents
- For a pole barn: whether it is heated or will be, which changes how the roof is done
What JMB supplies
- Prep: old insulation out, surfaces cleaned, windows, floors and equipment masked
- Closed-cell spray foam by kit for small areas, or by our spray-foam partner's rig for large ones
- Correct thickness for the code range for the location, sprayed in lifts
- Thermal or ignition barrier over the foam where the code requires it: drywall or intumescent coating
- Framing, furring or strapping needed before or after the foam
- Ventilation of the space during cure and cleanup of overspray
- Photos of the finished foam before it is covered, in your job folder
How it is priced: per project
Quoted in writing from your photos within one business day. What moves the number:
- Square footage sprayed and the thickness the location calls for
- Closed-cell vs. open-cell
- Kit-sized job vs. one that needs the partner rig and a mobilization
- Prep: removing old batts or fiberglass, masking a finished space
- Thermal barrier over the foam: drywall vs. intumescent coating
- Access and height: a pole barn ceiling from a lift vs. a basement wall from the floor
- Framing or strapping needed to hold the finish over the foam
Photos and rough dimensions are enough. Tell us whether the space is finished or will be, since that decides the thermal barrier.
How long it takes
Rim joist or a small wall by kit: half a day. Basement walls or an attic with the partner rig: one to two days plus cure time before the space is used. A pole barn: two to three days.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized quote within one business day. We only come out to measure first when the job needs a tape measure — no pressure, no games.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Rim joist
The best small spray foam job in the house. The rim is sprayed in one pass, sealing the sill and every penetration. Usually done by kit. See the rim joist page for the foam board alternative.
Basement walls
Closed-cell foam sprayed on the concrete or block, with the rim done at the same time, then framed and drywalled over it. It keeps the wall dry and warm and replaces the plastic-and-fiberglass basement walls that grow mold.
Attic roof deck and cathedral ceilings
When the attic has to be conditioned, or a sloped ceiling has no room for vents and batts, closed-cell foam on the underside of the roof deck makes an unvented assembly. It needs the partner rig and a thermal barrier over it.
Pole barn walls and roof
Closed-cell foam on the inside of the metal skin stops the roof from sweating on the first warm day of spring and makes a heated shop possible. Sprayed with the partner rig; our crew does the girt framing and the liner panel or drywall over it.
Foam kit touch-ups
A bonus room over a garage, a few bays in a cantilever, a small crawl space, or sealing around a new window or door. Kit-sized jobs done in a visit without a mobilization.
Spray Foam Insulation — Closed Cell for Attics, Rims and Pole Barns: questions, answered
Open cell or closed cell spray foam in Minnesota?
Closed-cell, almost always. It insulates more per inch, stops water vapor, and adds strength to a roof deck or a metal wall. In a cold climate that vapor control matters; open-cell foam lets moisture through and needs its own vapor retarder on the warm side. Open-cell has a place for sound or for interior walls, but for anything touching outside in Minnesota we spray closed-cell.
Do you spray foam yourselves or use a subcontractor?
Both, depending on size. Rim joists, small walls and touch-ups are done by our crew with two-part foam kits. Whole attics, basements and pole barns need a truck-mounted rig, and that is sprayed with our spray-foam partner when a rig is needed. Our crew does all the prep, the framing and the finish, and you deal with us for the whole job either way.
Can you spray foam a pole barn?
Yes, walls and roof. Closed-cell foam sprayed directly on the inside of the metal panels stops condensation and insulates the building in one step, and it stiffens the panels. The trade-off is that the metal is then bonded to the foam and hard to replace later. We spray it with the partner rig and frame the liner panel or drywall over it.
Does spray foam need to be covered?
In living space, yes. The code requires a thermal barrier, usually drywall, between foam and any room people occupy, and an ignition barrier in attics and crawl spaces that are only entered for service. Rim joists have their own limited exception. We include the covering on the quote so there is no surprise at the inspection.
Is spray foam safe to be in the house with?
Not while it is being sprayed or curing. The foam gives off fumes until it cures, and the sprayer works in a respirator. We ventilate the space and you stay out of the house for the period the product calls for, usually the rest of that day. Once cured, closed-cell foam is inert and has no smell.
Is spray foam worth it for a regular attic?
Usually not. A flat attic with a vented roof above it is best served by air sealing the ceiling and blowing cellulose or fiberglass over it, for a fraction of the cost of foam. Spray foam on the roof deck is for attics that have to be conditioned, cathedral ceilings and roof slopes with no room for anything else. We will tell you which yours is.
Get a written quote for this job
Three photos and a sentence is enough. You hear back within one business day. Or text the photos to 763-204-2099.
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Read morePage reviewed September 24, 2026 · JMB Builders LLC, MN license BC809005 · All insulation pages
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