Extruded Polystyrene XPS Board 100 mm Rigid Panel For Foundation Wall Insulation

Foundations put insulation in the hardest position on a project: permanent soil contact, backfill pressure and a wet, alkaline environment. The FL500 board answers that with 500 kPa compressive strength at 100 mm, enough for ground-bearing slabs and strip footings that transfer structural load through the insulation layer. Because the foam is closed cell, the board does not act as a wick, so the declared conductivity is retained even when the ground stays damp.

The board is extruded as a single homogeneous sheet, so there are no laminated faces to delaminate in wet ground and no fibre to take up moisture. Dimensional stability of 0.3 to 1.0% at 70 C keeps the panel flat against the footing face, which matters when the insulation also forms the backing for a damp proof membrane. The FL500 extruded polystyrene board is supplied in standard sizes of L 1200 / 2400 mm, W 600 / 1200 mm, THK 30 - 140 mm, and the board can be cut on site with a fine toothed saw or a hot wire, which keeps the cut face closed.

Technical Data

Applications

Used wherever the insulation is buried and must carry structural load without losing thermal performance.

• Foundation insulation for buildings without a basement
• Ground-bearing slabs and raft foundations
• Strip footings and slab edges below damp proof course
• Soil contact walls and retaining structures
• Under-slab insulation for unheated ground floors

Key Advantages

• 500 kPa compressive strength carries backfill and slab edge loads at 100 mm thickness.
• Closed cell foam keeps water uptake at or below 1.5% by volume in permanent soil contact.
• Conductivity range of 0.026 to 0.035 W/(m.K) holds with moisture present.
• Dimensional stability within 1% at 70 C keeps panels flat against the footing.
• Shiplap edges close the joints against soil fines and water movement.

Each 500 kPa Extruded Polystyrene Foundation Board is checked for thickness, compressive strength and dimensional stability before it is packed, and the batch figures travel with the delivery note. 500 kPa Extruded Polystyrene Foundation Board sheets are packed on edge on pallets, strapped and wrapped, so the edges and the faces arrive as they left the line. Where a project needs one grade across several details, the 500 kPa Extruded Polystyrene Foundation Board can be cut from the same sheet for walls, floors and edges, which keeps the specified values consistent. The 500 kPa Extruded Polystyrene Foundation Board is stocked in the standard sizes listed above, and cut sizes are produced to the layout drawings supplied with the order. On site the 500 kPa Extruded Polystyrene Foundation Board is handled as a finished product: no coating, no wrapping and no curing is needed before the next layer goes on.

Installation Notes

• Boards are laid with joints staggered and edges fully engaged over the whole face.
• Surfaces in contact with adhesive or membrane are cleaned and primed before the board is bedded.
• Boards are cut oversize by 10 mm where a tight fit into a frame or reveal is needed, then trimmed.
• Finished layers are protected from site traffic until the covering layer is in place.

FAQ