Structural Insulated Panels or SIPs

A SIP is a sandwich structured composite of two materials - typically a rigid foam core with two skins of timber. The core provides the insulation and air tightness properties whilst the skins provide the structural strength. We use Oriented Stranded Board (OSB) for our skins around a polyurethane foam core.

The best performing SIPs are made by injecting a polyurethane foam between the two skins, the foam expands and glues itself permanently to the skins forming a highly robust structure which strongly resists delamination. The foam is "closed cell" meaning it's moisture proof, air tight and highly insulative, (in contrast to a bath sponge which might appear similar but is open cell).

So why not just glue two timber boards either side of a slab of solid insulation? Firstly because the joints between OSB, glue and insulation are weaker than the injected foam approach. When under load, the surface of the foam can rip free from the glue and the panel disintegrates. Secondly, a glued panel rarely achieves the same thermal and air tightness performance of an injected panel; an injected foam expands into all small gaps and pores and seals them up, something that is harder to guarantee with glue.

Where are SIPs used?

SIPs are used to create walls, floors and roofs, in short they are used to form the entire structure of a building.

The advantages of using them for walls are obvious, but when you use them for roofs there's an unexpected advantage: Pitched roofs in SIPs need far fewer structural members than a traditional timber framed build - you can have spacious, uncluttered vaulted ceilings as the roof frames, beams, joists are not needed (or are hidden within the SIP joints)

When used as a floor deck the heat lost to the ground is dramatically reduced, evening out the temperature in the room for increased comfort.

SIPs Technical Information

Under construction. Work is in progress.

Please bear with us whilst we add detailed information about SIPs here. Typical U values, dimensions, weights