A Structural Insulated Panel is a sandwich of an internal core that is an insulating material like polyurethane foam between outer sheaths that are often made from plywood or MDF.

Being a composite product; Structural Insulated Panels, commonly referred to as SIPs, have a structural strength and integrity far greater than those of the individual components. SIPs are so strong they can be the main load bearing structure in a building and can carry the weight of floors and roofs. The efficiency of the insulating properties of SIPs, makes them ideal for use in constructing outdoor buildings that are not directly attached to your main home property.

Uses of Structural Insulating Panels

Structural Insulating panels can be used in just about any construction project. Despite having been around in one form or another for about 50 years, currently they’re only used in about 5% of homes properties. However, even if a builder prefers to use a conventional timber or light gauge steel frame, SIPs can still be attached to them to increase the structural properties of the building an act as a highly insulated wall face.

For the DIY or Home Enthusiast, using Structural Insulating Panels to build a garden office or studio, home gym or other outdoor building - is a convenient, cost effective and environmentally friendly option to consider.

Types of Structural Insulating Panels

SIPS come in a variety of sizes and materials to suit the various purposes they can be used for. The most common kind of SIPs use insulation made from either expanded polystyrene or polyisocyanurate, a polyurethane derivative.

Most SIPs are made from expanded polystyrene (EPS) foam board or beadboard insulation. There are two types: molded expanded polystyrene (MEPS) and extruded expanded polystyrene (XEPS) foam board. This type of SIP has a nominal R-value of about 4 per inch (2.5 cm) to 5 per inch of thickness.

Compressed Straw Core SIPs are are also available; these are more environmentally friendly than the other types since they are made from recycled waste agricultural straw. On the negative side, straw SIPs give less insulation value per inch of thickness, and they are much heavier.

The standard wall panel size is 48×96 inches; these weigh 110 pounds each. The depth of a wall or floor panel will be 3.5 to 7.5 inches; whilst most flat ceiling panels will also be around 5.5 thick, they can be up to 11 inches thick.

You can buy structural insulating panels from your local builders stores and merchants or online. Usually you’ll also be able to find somewhere that can supply you with a pre-engineered kit of SIPs to meet the job you want to do, which will save you a lot of time and effort in planning and designing the building you want to construct.

How to Build a Garden Office Using SIPs

Using SIPs to build something outdoors really can be easy and here are some hints on setting about constructing a garden office using SIPs. As for any building a good foundation is essential and for your garden office a 150mm depth of treated timber will be fine, onto this secure the 125mm thick floor panels.

The wall panels can be engineered to interlock and be bonded together; the outer face of the wall panels is usually plywood and the inner face MDF. Both the inner and outer walls can be treated.

Outer walls should at least be given a water-proof treatment and will look even better if they’re clad in faux stone panels or a timber effect. Whilst internal walls can also be clad with a timber it’s more usual to install plaster-board and paint it, or just paint the bare MDF surface.

A pre-engineered garden office will already have a door and windows cut into it, you can of course order suitable windows and doors when ordering the SIP garden office itself. The roof SIPs will probably have asphalt tiles for weatherproofing on the outside and either a plywood or MDF finish on the inside; that can be painted.

All that remains then is to fit a laminated floor surface and a skirting board, run some electrics to it with an outdoor connector until an electrician can connect you properly, move in your furniture and start to enjoy the extra space and views you’ve got in your SIPs garden office.