Essential Guide to SIPs

March 1, 2017

What are SIPs?

Structurally insulated panels (SIPs) are a building system and form a strong, lightweight structure which is fast to erect and offers extremely good thermal performance.

The factory-produced panels consist of two parallel faces: usually orientated strand board (OSB) sandwiching a rigid core of closed-cell polyurethane foam or expanded polystyrene.

The resulting panels are strong, lightweight, quick to erect and free from problems of compression shrinkage and cold bridging. High levels of insulation can be achieved in thinner wall thicknesses than other forms of construction and can provide a fast way of building very efficient walls which require no additional frame or skeleton to support them.

How are they used?

SIPs can be used as the inner skin of a cavity wall, as a self-supporting single skin structural wall in place of timber frame or blocks and as a pre-insulated roofing structure. They may also be used in floors.

SIPs are a very flexible product and can be used with any external cladding, including brick, render, weatherboarding or aluminium. They can also be roofed with slates, tiles or metal coverings. Internally, the panels can be simply finished with plasterboard and a skim coating with services cavities where needed. Using SIPs will decrease build times.

Incorporating SIPs into your project

It is important that SIPs are incorporated into the overall design of your project from the start, therefore it is important to choose a designer that has experience of working with SIPs and understands the structural implications of a panel system. The panels are custom designed for each project and cut to order. They can also include service ducting, which makes wiring extremely easy but does mean the electrical layout will need to be planned at an early stage in the design process. Alternately, services may be run through internal partition walls, with wiring passing through the cavity between the panel and internal plasterboard, or through a double layer of plasterboard.

What are the benefits of SIPs?

As a method of construction SIPs offer high levels of insulation, structural strength and airtightness, with thinner wall sections. They also increase the available roof space, thanks to their truss-free construction, enabling rooms to be created in the roof providing substantial living accommodation.

Being fabricated off-site, they can be delivered pre-cut and pre insulated in a matter of days, lowering labour costs and enabling quicker occupancy.

With SIPs being lightweight, a reduced foundation specification can be used.

The OSB creates a continuous surface onto which radiators, kitchen cabinets and light fittings may be easily fixed with little or no additional support and both the OSB and insulation core are resistant to attack by mould and microbes and provide no food value to vermin.

The jointing techniques used in SIPs buildings mean that the sound transmittance through joists is reduced, which helps to decrease sound transfer between rooms.

And the disadvantages

Making on-site changes isn’t really an option with SIPs – the majority of decisions need to be made early on and finalised before the panels are produced and the build begins.

SIPs are generally viewed as costing more than standard timber frame construction, partly because the insulation is already installed in the panels, but increased build speed, reduced waste, less manpower and a reduction in site machinery help to offset this extra expense.

Welsh Oak Frame offer a range of tailored walling systems including SIP’s on top of our basic oak frame package. For more information, please call us on 01686 688 000

Photo credit: Kingspan Insulation Limited