structural insulated panel for extension

The Structural Insulated Panel, or SIP, is a concept that emerged as far back as 1937. It was invented when the United State Forestry Service was looking for ways to conserve forests. The SIP system is a more advanced type of Closed Panel, which can offer high insulation values and accelerated build schedules. It delivers excellent structural and thermal characteristics in a single system. The panels, usually Oriented Strand Board (OSB), sandwich a rigid insulation core, often polyurethane. The result is a lightweight system with a minimum wall thickness which is both quick to erect and airtight. The major disadvantage is the polyurethane filling which is not in step with more environmentally-friendly materials.

SIP systems can be several times stronger than a standard timber-frame structure and they are therefore ideal as walls, roofs and floors of self build houses. This system is an excellent solution for the creation of a living space in the roof zone as there is no need for roof trusses. The result is that maximum space becomes available.

Similar to Closed Panels, they can be delivered on site with windows and doors already installed, complete with plasterboard lining and first-fit electrics. External cladding can be bricks, timber, render or stone.

SIPs have the same advantages as Closed Panels with a few extra features:

  • U-values as low as 0.11 W/m2K can be achieved through the use of SIPs whilst also limiting the increase in wall thickness, so maximising available room space.
  • The lightweight nature of the panels can lead to a reduction in foundation loadings, giving the structural engineer flexibility of design, and often meaning a reduction in groundwork costs.
  • ideal for adding to existing structures, such as converting bungalows into two storey houses
  • heating costs will be lower than homes built with other systems.
  • easily comply with the air-leakage test for all new builds