Bookmark

Open PDF

Print Friendly

Product

The Polyfoam Slimline System consists of a high performance 100% ozone friendly, extruded polystyrene, rigid board insulation which is lightweight, yet has excellent structural strength and long term effectiveness. It is supplied with the Slimline membrane and is specifically designed to reduce the passage of water and improve the thermal performance of a protected membrane roof.

Typical Construction

Protected membrane roof with paving slabs for use as a pedestrian area.

Installation

To create a roof terrace/patio area, paving slabs at 50mm thick are an alternative to gravel ballast.

The waterproof membrane must be free of loose gravel and grit before the insulation board is laid.

On existing roofs, any existing chippings should be covered with a polyethylene cushion layer, such as Polyfoam Floorfoam.

For single ply and tanking membranes, a separating sheet should be laid immediately below the insulation and turned up at all upstands.

The boards should be laid in a staggered pattern from the point of access to the roof. All joints should be tightly fitted. It is important that all joints between boards are tight fitting and there are no gaps at the junctions with rooflights, upstands and other roof projections.

The Polyfoam Slimline membrane is loose laid over the insulation, at right angles to the slope, with 300mm side laps. At all upstands and penetrations, turn the membrane up so it finishes above the ballast level.

Paving slabs should then be laid on spacer supports at each corner.

Each layer is laid on an advancing front in order to protect the waterproofing membrane from mechanical damage as the materials are transported across the roof.

At upstands, exposed areas of the waterproof membrane should be protected from solar radiation. Where Polyfoam Roofboard is used at upstands to minimise thermal bridging, it should be covered with a flashing to protect it from exposure to ultra-violet light. Alternatively, Polyfoam High Impact and Upstand Board may be used.

Performance

Compression resistance

All materials are compressed under load. If the roof is going to be transformed from a limited access waste of space into an interesting and useful space the insulation must be capable of accommodating applied loads. Polyfoam Roofboard is highly resistant to compression and withstands both occasional and long term static loads. A factor of safety for design loads of 3 (5 for long term static loads) is applied to the compressive strength of the product.

Moisture resistance

Polyfoam Roofboard is often used above the waterproofing layer and thus exposed to rainwater. The board is resistant to moisture absorption and can be laid in standing water or up against wet concrete with minimal impact on the performance of the product.

Thermal insulation

Polyfoam Roofboard Extra is a high performance insulant with a thermal conductivity of 0.029 W/mK

The actual performance in use of Polyfoam Roofboard Extra is outlined in the below U-value table.

Typical U-Values (W/m²K) of roof terraces insulated with the Polyfoam Slimline system

Advantages

• Highly cost effective solution with compressive strength to support the point loading of paving slab supports
• High thermal performance due to Slimline System
• Compatible with regular pedestrian roof traffic
• Allows the creation of patios, roof terraces and balconies
• Protects water proofing membrane from UV degradation and temperature extremes increasing the membranes in service life
• Thermal performance of the Polyfoam insulation is unaffected by moisture