What are SIP's Panels?

• Pre manufactured insulated wall and roof panels that also provide the structure of the building
• At the same time SIP’s provide exceptional insulation properties. Put simply SIP’s when used as both wall and roof construction provides the ultimate solution for low energy consumption buildings.
• The design of the building and both interior and exterior looks are provided by cladding and lining.
• As the name suggests, the panels have the properties and benefit of being both a structural unit and an insulating panel. Claddings and linings can be applied directly to the panels to form a complete building.
• SIP construction differs from timber frame techniques.
• In timber frame, the strength of the system is derived from the frame. With SIP’s, the strength is derived from the whole unit.
• SIP buildings behave as thin shell structures dispersing loads throughout the entire surface area.

General Description of SIP's

The construction of a SIP panel comprises outer layers of OSB (Orientated Strand Board) with a rigid polyurethane foam core.  The panels vary in total thickness between 100mm and 220mm. Panels are usually made in 1200mm widths, though this can be varied.  The panels are then joined together using a glued ‘spline’ joint to form the element being constructed.  

The construction process of the panels is that the polyurethane is injected between the OSB layers under pressure.  This ensures a full fill of the void and forms a bond with the OSB.  It is the bond between the OSB and the polyurethane that gives the panel its structural performance.

Design Principles

For the purposes of design, the compressive strength of the panel is determined by using the compressive strength of the OSB boarding

For the design of the wall panels, an assessment of the combination of bending and compressive stresses on the panel is made using the same techniques as that for structural timber

To obtain the maximum benefit using a SIP system, the strength of the wall should be utilized as far as is practically possible to support roofs and floors.  When this cannot be done, it is usual to use beams and posts to provide the additional support.  The most common situation where this arises is when purlins are used to support roofs.

Together with the other benefits such as extremely good thermal properties, ease and speed of construction and off site manufacture, it is seen that SIP panels can produce a robust and efficient modern form of construction.