SIPs vs Timber Frame for Garden Rooms

How the two methods differ

Structural insulated panels (SIPs) combine structural facings and an insulating core in a prefabricated panel. A timber frame uses structural studs with insulation and other layers added to form the wall. Either method needs a suitable foundation, weather protection, ventilation, glazing and careful junction details.

Compare complete wall and roof designs

Ask for the proposed build-up and calculated whole-element U-values, including thermal bridges at studs, joints, openings and the floor-to-wall junction. A centre-of-panel figure does not describe the finished room. Airtightness and moisture control depend on detailing and workmanship in both systems.

See our Part L guide to check which energy rules apply to the actual project.

Programme, access and changes

Prefabricated panels may shorten some on-site stages, while a timber frame can be easier to adjust during construction. The overall programme still depends on design, manufacture, foundations, delivery access, services and weather. Ask each installer for a realistic sequence for your site, especially if access is narrow or through a flat.

Ask for comparable quotes

• Request the same size, glazing, external finish and interior specification from each installer.
• Ask who designed the structural system and how the panels or frame will be delivered.
• Compare thermal calculations, ventilation, moisture details and warranties.
• Check what testing and completion documents will be provided.

Materials and environmental claims also need evidence for the actual products. See our sustainability guide and cost guide.