SIPs in walls, roofs and floors. Can one panel do all three jobs?

For each application, establish the panel thickness, facing specification and support layout. Check how the layers are bonded and how adjacent panels connect. Use data for the selected system. Thermal resistance alone cannot tell you whether a panel will be stiff enough as part of a roof slope or a floor between storeys.

A wall panel can carry vertical loads and contribute to bracing where the design provides for this. Its connections at the base and at upper floors must transfer those forces. Windows and doors interrupt the load path. Each opening needs a detail showing how forces pass around it.

The wall insulates the interior and forms part of the airtight envelope. It needs protection from rain on the outside and a suitable lining inside. A polyurethane core can provide good insulation within a modest thickness. Compare the complete wall, including joint components and additional layers.

A roof panel may carry the weight of the roof covering and associated layers as well as snow and wind loads. Its span and the direction in which loads reach the supports matter. Check deflection and the connections at the ridge, eaves and openings. A PIR or PUR core designation alone establishes none of these design conditions.

A roof slope needs a complete weatherproof build-up. An OSB facing on its own is unsuitable as an exposed permanent roof covering. The roof system determines the substrate, membranes, any ventilation cavity and the final covering. Service penetrations and drainage also need appropriate details.

Floors carry occupants, furnishings and the floor build-up itself. Deflection and vibration felt underfoot affect comfort. Good insulation does not establish a panel’s suitability as a floor. Where the system permits SIP floors, the design should specify support spacing, connections and additional layers.

Between storeys, assess airborne and impact sound for the actual assembly. An insulating core cannot automatically take the place of acoustic layers. A house with SIP walls may therefore have a different floor structure. Each assembly can be selected to meet the requirements of the building as a whole.

A panel spanning a driveway or open space needs adequate support and protection on the underside. In a ground-bearing floor, the relevant conditions include contact with adjacent layers, moisture and load transfer. A specification that calls both products a ‘floor panel’ misses these differences.

Rigid foam in a panel does not establish suitability for continuous contact with water or soil. Consult the product documentation for its intended uses. Polyurethane boards have a range of insulation applications. A load-bearing panel with wood-based facings is a distinct assembly, and every layer needs suitable service conditions.

The wall-to-roof joint must transfer forces and maintain continuity of insulation and seals. At a floor, detail the bearing and connection to the storey above. Different materials and load directions meet at these junctions. Sections through the actual building show details that a drawing of an isolated panel cannot convey.

Plan the assembly sequence as well. Installing the next panel can make a seal or fastener inaccessible. Where details are agreed in advance, prefabrication allows these locations to be prepared at the factory. The benefit is a repeatable joint detail as well as rapid enclosure of large areas.

List the requirements for walls, roof slopes and floors separately. For each, define its function, loads, insulation and finish. Then identify the components in the selected system that meet them. SIPs can be combined with other structural systems where the interfaces are designed accordingly. One house may therefore use several types of element.

This approach puts the polyurethane core where its insulation is most useful while retaining the necessary load capacity and comfort. Check each application against both the product documentation and the building design. Walls, roofs and floors can then work together while performing different tasks.