Technical Info



The SIP Building System consists of structural insulated roof and wall panels, which can be used to create buildings with a maximum of 2 storeys plus a room-in-roof construction. Because of their light weight of 25kg/m² they are ideal for use, where heavy constructions are not possible.


Structural Insulated Panel Dimensions
Thickness: 150 mm (2 x 16 mm OSB 3 +110 mm rigid urethane insulation)
Width: 200 mm (min) - 1245 mm (max)
Length: 7450 mm (max) – for walls a maximum 3m storey height is allowed.

The SIPs panels consists of two facings of 11mm OSB [oriented strand board] bonded by pressure injection to CFC free/ODP zero polyurethane closed cell foam. The option of 15mm OSB is also available. The facings and core act as a composite structure.

OSB/3 board comprises softwood flakes/strands bonded together with MUPF (melamine urea-phenolic) resin, MDI (diisocyanate diphenylmethane) binder and waxes. The board is manufactured to the specification detailed in BS EN 300 : 1997 for OSB/3, load bearing oriented strand boards for use in humid conditions.  All OSB/3 is from sustainable timber sources.


Overall thickness 150 mm (2 x 11 mm OSB 3 +128 mm rigid urethane insulation)
Width up to 1200mm
Wall heights up to 3000mm
Roof panels up to 6500mm

Other widths and thicknesses are available on request.


The thermal conductivity of the polyurethane core is typically 0.025 W/m.ºK.  Using the SBS  SIPs panel can provide extremely low U-values for walls. Depending on detail of construction this can be in the range 0.21 to 0.14 W/m².ºK.  For roofs designs can deliver U-values in the range 0.20 to 0.12 W/m².ºK.


Fire performance
The  SIPs panel will meet all the requirements in the Building Regulations with regard to fire resistance when lined with plasterboard. These requirements are similar to those for timber frame construction.  A single layer will provide 30 minutes rating and a double layer 60 minutes rating.





Acoustic insulation between rooms and externally is improved by the plasterboard lining. SBS can advise on constructions to achieve levels of sound reduction required by the Building Regulations.


A building constructed with SIPs panels will have durability comparable to other forms of construction. As long as the design follows best practice and the building is maintained and weather tight, a life of at least 60 years may be expected.


Air tightness and Ventilation
Use of the SIPs panel and jointing system can create an airtight structure that will meet requirements in the new Building Regulations. Such is the effectiveness of the system that positive ventilation methods should be considered. At the same time positive ventilation systems can be linked to heat recovery that can save energy costs. 


Structural performance

SIPs form a light and strong structure
Excellent for in-plane loads
SIPs buildings behave as thin shell structures, dispersing point loads to the entire surface area.

SIP panels have been subjected to a number of testing procedures.  These include loading the panels with a uniformly distributed load (‘udl’) to measure strength and deflection between two supports, axial loads centrally and eccentrically placed, racking loads and shear and bending loads on the panel joints.
The strength of the joints between the individual panels is such that panels can be used to span over openings and be supported by the panels each side.  It easy to incorporate additional timber to support localised concentration of loading.  Routinely this is done at the joints in the panels.  However, with careful detailing, much of this can be avoided.


Uniformly distributed load
Tests have shown that the panels have a very high ultimate bending strength. Deflection, calculated as described in the Design Guide, is the governing criterion in design. This increases user confidence knowing that safe working loads are well in excess of standard deflection limits.


Axial load
Axial loading tests on panels 100m thick, 2.4m in height and 2.4m in width were seen to fail at a load of 440kN/m. Using a factor of safety of 2.0 it is seen that panels will comfortably support a vertical load of 90 kN/m. These loads are well in excess of the average foundation loading from a typical two-storey house of traditional construction.

Advantages of SIPs

Excellent thermal performance – insulation U-value, lack of thermal bridging and air tightness
Environmentally friendly – ODP zero insulation core and OSB from sustainable forest resources
Save construction time and cost – large engineered components
Space-maximising design flexibility -  3-bed houses can be 5-bed houses for little extra cost
Light-weight structural strength – saves on foundations. Pile and pad foundations are a real alternative



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