Flexxboard25 - Construction Grade Insulating Foam Board

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If you’re planning to pour a concrete driveway, sidewalk or a patio this summer, use FlexxBoard25 foam board insulation. Two-inch 4-by-8 sheets of high density FlexxBoard 25 insulate concrete slabs to protect from frost expansion and cracking.

FlexxBoard25 increases the life and structural integrity of concrete for exterior and interior applications.

In addition to exterior concrete slabs, such as driveways, sidewalks and patios, some interior applications for FlexxBoard25 include concrete slabs for basements, structural fill, shop/garage slabs and concrete floors.

FlexxBoard25 can be purchased at most building supply centers.

For more FlexxBoard25 homeowner information, click here!

FlexxBoard25 for Homeowners


Attention Professionals!

FlexxBoard25 goes beyond driveways or sidewalks. Monuments, sports fields, and much more can be built a new way! Without cracking and buckling due to frost!

For more professional info click here!

Frost Protection that Bonds to Concrete!

Grey is better

FlexxBoard25 bonds itself to concrete resulting in a stronger, more durable insulation. The foam will not rot or deteriorate when exposed to natural elements.

Competing colored foam boards (Extruded Polystyrene) because of it’s smooth finish is known to separate from concrete. This will ultimately diminish R-value and result in the need to replace the concrete in the future.


FlexxBoard25 Brochure


Product FlexxBoard 25
Overall Dimension 48" x 96"
Density Classification 2.0 pcf
Staple Pull out Strength

29 lbs.

Thermal Resistance (R-Value) @ 75º 2 inch = R-9
Strength Properties, minimum
Compressive Strength
Dimensional Stability
Oxygen Index
Thermal Conductivity K Factor @ 75º F

psi - 32.8

Moisture Resistance, Maximum
WVT (water vapor transmissioin
Absorption (vol.)

perm./in. - 2.65
% - 2.4
- none