What are SIPs?

SIPs or Structurally Insulated Panels consist of two outer layers of Oriented Strand Board (OSB) sandwiched around an Expanded Polystyrene (EPS) foam core. Each composite panel is robust, lightweight and extremely strong – up to seven times stronger than a timber frame. SIPs are incredibly well insulated and airtight, resulting in a structure that required less energy to heat and one that provides better air quality for the user.

SIP panels have been used in the USA, Canada, Japan and Europe since the 1950s where they have become a mainstream building material for constructing homes. Now, SIPs are becoming increasingly popular here in the UK.

Building with SIPs as the structural element for property walls, roofs and suspended floors is quick, easy and cost-effective. Timber splines between the panels ensure a structurally-sound framed system with panels fixed to the footings via a timber sole plate and to the ceiling via a timber ring beam. There’s no risk of the compression shrinkage or cold bridging that is normally associated with stud walls and other traditional methods.

Panel components

Our SIPs use 15mm Sterling Board OSB3 skins as standard. Sterling OSB3 is a precision-engineered structural board that is an industry recognised as a structural material for use in load-bearing conditions. Sterling OSB3 is BBA approved and conforms to Eurocodes. Sterling OSB3 is also FSC® certified and made from timber grown in the UK. It is manufactured here too, meaning fewer carbon miles are clocked up during transportation.

For the foam core of our SIPs we use 100 Grade EPS from Jablite – the UK’s largest producer of EPS products for the construction industry. EPS is non-toxic and biologically inert. Containing a flame-retardant additive, it has a reaction to Fire Class E, a high strength-to-weight ratio and very low thermal conductivity (W/mK, at 10°C) of 0.032.

We laminate the OSB3 skins and EPS foam together to form SIPs using polyurethane glue and leave to cure under pressure in our press. Polyurethane is incredibly strong and once cured, the three layers that get laminated together create a SIP panel that can withstand incredible stresses. To see just how strong SIPs can be under extreme pressures, we recommend you watch this short video clip.

The timber used to create the outer skins and structural framework of our SIP panels come from FSC accredited plantations. We used C4 grade, tanalised structural timbers for stud work, splines and framework. Timber is naturally low in thermal conductivity, it’s 15 times better as an insulator than concrete and 400 times better than steel.

SIPs design flexibility 

SIPs building systems offer enormous versatility. Walls can be externally clad with brick, render, weatherboarding or metal and roofing possibilities include slate, tile or metal for example. Internally, SIPs can simply be finished with plasterboard and a skim coating with service cavities as required.

The thicknesses and sizes of SIPs can be tailormade to your individual project requirements at our own New Forest SIPs workshop. You read more about the specifics and sizing of our SIPs on our product spec page.

To find out about the advantages of using SIPs, please see our project benefits and environmental benefits pages.