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Rigid Foam Insulation Calgary
Rigid foam insulation is factory-made board insulation, sold as XPS, EPS or polyiso, that you cut to size and fix over walls, floors and roofs. It gives a steady R-value per inch, handles moisture better than batts, and slows the heat that escapes through studs. For Calgary basements, slabs and low-slope roofs, it is one of the most practical ways to add R-value without adding much thickness.
The three types of rigid foam board
| Type | Approx. R per inch | Strengths | Best for |
|---|---|---|---|
| XPS (blue, pink or green) | R-5 | High compressive strength, very low water absorption | Below-grade walls, under slabs |
| EPS (white bead board) | R-4 | Lower cost, several densities | Above-grade walls, roofs, ICF |
| Polyiso (foil-faced) | R-6 | Most R-value in the thinnest board | Above-grade walls, roofs |
Polyiso loses some performance in very cold weather, so it suits exterior and roof work better than cold-side foundation walls. For a wider technical overview, see this rigid panel insulation summary.
Where rigid foam makes sense in Calgary
Basement walls. Fix boards to the interior face of the concrete, seal the seams, then frame in front. Fibreglass alone against cold concrete invites condensation.
Under slabs. Choose a higher-strength XPS or Type 3 EPS so the board carries floor loads without crushing.
Exterior walls. Continuous insulation outside the sheathing breaks the thermal bridge through studs. Pair it with house wrap for a clean weather barrier.
Rim joists. Cut-and-seal pieces are a common fix for a cold basement perimeter.
Low-slope roofs. Tapered EPS or polyiso layers handle drainage and R-value together.
How to pick thickness
Start with the R-value your plans or local code call for, then divide by the board’s R per inch. A 2-inch XPS board lands near R-10, and a 4-inch board near R-20. Targets differ between new builds and renovations, so check current Alberta Building Code and municipal energy requirements before you order. If space is tight, choose polyiso or thicker XPS. If budget matters most, EPS usually costs less than XPS.
Rigid foam or spray foam?
Boards are cut to shape and sealed at the seams. Spray foam goes on wet and expands into gaps. Boards suit big flat surfaces such as basement walls, slabs and roofs, and they are easy to buy and install yourself. Closed-cell spray foam seals awkward shapes in one pass but needs certified installers and costs more. Many Calgary builds use both: boards on the flat areas, spray foam at penetrations. See our spray foam insulation page for that side.
Installation basics
Keep boards dry and flat until use. Cut with a fine-tooth saw or utility knife, butt the edges tightly, and tape or foam the joints so air can’t slip through. Use adhesives rated for foam, because solvent-based products can dissolve polystyrene. Indoors, foam plastic normally needs a thermal barrier, typically 1/2-inch drywall. Confirm the requirement with your inspector. Where the board isn’t your vapour control layer, add a polyethylene vapour barrier.
Common mistakes include skipping seam sealing, using board that is too thin against a cold foundation, choosing the wrong adhesive, and leaving foam exposed indoors.
Order rigid foam from Paradise Building Supplies
Paradise Building Supplies has supplied builders, contractors and homeowners across the GTA and Calgary. Our Calgary location at 260085 Range Rd 293 also stocks what goes with foam board: metal framing, drywall, vapour barrier, house wrap and sealants. One order means fewer trips. Tell us which wall, floor or roof you’re insulating, and we’ll help match board type, thickness and accessories.
Ready to price your job? Request a quote or call our Calgary team at 877-908-9598. You can also browse all products or contact us.
Manufacturer references: SOPREMA XPS boards and Plasti-Fab Alberta EPS.
The body is roughly 800 words, and the FAQs below are extra.
FAQs
What is the best rigid foam insulation for a Calgary basement?
XPS is the usual choice for basement walls and under slabs because it resists moisture and carries load. EPS is a lower-cost alternative when moisture exposure is limited.
What is the difference between XPS, EPS and polyiso?
XPS is about R-5 per inch and moisture-resistant. EPS is about R-4 per inch and cheaper. Polyiso is about R-6 per inch but loses some performance in deep cold.
How thick should rigid foam be in Calgary?
It depends on the R-value your plans or code require. Divide that target by the board’s R per inch. For example, R-10 needs about 2 inches of XPS.
Do I need drywall over rigid foam indoors?
Usually yes. Foam plastic normally needs a thermal barrier such as 1/2-inch drywall. Confirm with your local inspector.
Can rigid foam replace a vapour barrier?
Sometimes, when the board is thick enough and the assembly is designed for it. Don’t assume it. Confirm with your designer or inspector.
Is rigid foam better than spray foam?
Neither is better in every case. Boards suit large flat areas and DIY work. Spray foam suits gaps, rim joists and irregular shapes. Many projects use both.
Does Paradise Building Supplies sell rigid foam insulation in Calgary?
Contact our Calgary team at 877-908-9598 or request a quote for current stock, sizes and delivery.