Foundation Insulation
XPS on the outside of basements and foundations — thermal protection that also bodyguards the waterproofing underground.
One System, Built to Work Together.
Below grade, insulation faces permanent ground contact, moisture and backfill pressure. XPS boards fixed outside the waterproofing insulate the basement and physically protect the membrane at the same time.
The perimeter build-up drains water down to the land drain while keeping basement walls warm and condensation-free inside.
- Heated basements and lower floors
- Perimeter and slab-edge insulation
- Cold bridge control at foundations
- Plant rooms below grade
- Frost protection of foundations
Layer by Layer.
- 01
Foundation Wall
The structural wall, prepared and made good.
- 02
Waterproofing Membrane
The tanking layer seals the structure against ground water.
- 03
XPS Insulation Boards
Boards fixed over the membrane — insulation and protection in one layer.
- 04
Drainage & Backfill
Granular backfill carries water down and away from the wall.
01Insulation That Protects
The XPS layer takes the backfill so the waterproofing underneath never does.
02Ground-Contact Rated
Closed-cell boards keep their R-value buried, wet, and under pressure.
03Warm, Dry Basements
Insulated walls stay above dew point — usable rooms instead of damp storage.
04Frost Defence
Perimeter insulation shields foundations from freeze-thaw cycling.
Common questions about this system.
Where is the Foundation Insulation system used?
It is typically used for heated basements and lower floors, perimeter and slab-edge insulation, cold bridge control at foundations, plant rooms below grade and frost protection of foundations.
Which Insutech products are used for foundation insulation?
The recommended system is built with Insu Foam, Iso Foam, Blue Foam and Insuboard Protection Board — full details for each are on the recommended products cards on this page.
How is the system installed?
The system is installed in 4 stages: foundation Wall, waterproofing Membrane, XPS Insulation Boards and drainage & Backfill. The system build-up section on this page illustrates the full sequence.
What are the main advantages of the foundation insulation system?
The key advantages are insulation That Protects, ground-Contact Rated and warm, Dry Basements — each is explained in the Key Benefits section on this page.