Applications
Under slab insulation
Board under the whole pour, so the slab stops losing heat into the ground and the floor above it stays dry. Rated from 40 to 100 psi, stocked in Duluth, delivered on the date your crew needs it.
Why it goes under everything
Concrete on the ground is a radiator pointed at the dirt
A slab poured on grade is in permanent contact with soil that sits well below room temperature for most of a Duluth year. Without a break between the two, the slab gives its heat to the ground continuously, and no amount of insulation in the walls changes it.
Our rule of thumb is short. If you are pouring concrete on the ground and it is not a footing, there is board going underneath it.
- Slab on grade. Houses, shops, garages and additions.
- Heated floors. Under the tubing, so the heat goes up rather than down.
- Driveways and aprons. Wheel loads and freeze thaw at the same time.
- Industrial floors and cold storage. Where the load governs the grade.
The board has to survive the pour
Sub slab board is walked on, loaded with rebar chairs, driven across and then buried for the life of the building. It has one chance to be right.
- 40 psi carries four times the load of 25 psi board
- Crews drive a power buggy straight across it
- 0.2 percent water absorption by volume
- 85 percent post-consumer recycled polystyrene
Wet insulation is failed insulation, and you cannot get back under a slab to fix it.
Which grade goes under which floor
Compressive strength is what separates the grades. Everything else, the R-value, the recycled content and the closed cell structure, is the same board.
ECO 40
Residential slabs, heated floors, garages and shop floors. The grade most jobs want.
ECO 60
Driveways, aprons and approach slabs. Wheel loads and freeze thaw together.
ECO 100
Industrial floors, equipment pads and cold storage, where compressive strength governs.
Not sure
Tell us the load and the assembly. We will tell you the grade, and say so if you do not need the upgrade.
Under slab questions
Do I still need a vapor barrier under the slab?
Yes. The board is a Class II vapor retarder at 0.71 perm and it does not replace a poly vapor barrier. Crews we supply still run 6 mil poly, and so do we on our own pours.
Why does moisture matter if the foam is buried?
Because saturated foam stops insulating. Expanded bead board takes on water until it performs about as well as nothing at all. This is extruded board at 0.2 percent absorption by volume, which is why it is the one type recommended in constantly wet or below grade conditions.
Can a machine be driven over it?
On 40 psi and above, yes. Crews run power buggies and mini skid steers directly across it without damaging the board, which keeps your pour reach and often removes the pump truck from the job. Ordinary 25 psi board from a big box store will not survive that pass.
How thick should it be?
That is a code and energy question for your builder or designer rather than a rule of thumb we should hand out. We stock 1 inch, 1.5 inch, 2 inch and 3 inch, and layers can be combined. Tell us the target and we will work out the sheets.
What about under a heated floor?
A heated slab pushes heat in every direction until you give it something to push against. Board under the tubing sends it up into the room instead of down into the subgrade, which is the whole reason a heated slab is insulated underneath rather than only around the edge.
What customers say
Trusted by the crews who pour the concrete
Five out of five across every Google review, from contractors across the Upper Midwest.
I have used them and their materials several times. Not only is their material far better than their competitors but the service is as well. I was in a jam and Caleb hand delivered what I needed within the hour. I highly recommend.
Amazing product! It is the only foam we will use beneath our concrete. It performs far better than its direct competitors at a similar price. Service has been excellent, and our materials always show up on time.
EFS is a top-notch supplier. Their high-density eco foam is an excellent new product, strong, clean, and reliable. Great quality materials and service we can count on. Highly recommend.
Eco foam in my opinion is the only foam worth using. The quality and strength of the foam impresses me every time I work with it and use it. I will be using Eco foam for all of my projects. [excerpt]
Best foam on the market. Great service and fast delivery.
Solid product and support.
Pick your material, pick your delivery date
Order online or text your reorder. We schedule the drop and it lands on site when your crew needs it.