SIPs structural insulated panels used in garden room construction
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Structure

Every Green Rooms build uses Structural Insulated Panels from floor to roof — no timber frame shortcutting.

SIPs Throughout

Why SIPs and Not Timber Frame?

A Structural Insulated Panel is a rigid foam insulation core bonded between two structural boards — one component that is simultaneously structure, insulation and vapour barrier. Timber frame buildings need separate layers for each of these functions, which introduces gaps, thermal bridges and long-term performance risks. We use SIPs for every element — floor, walls and roof.

01 — Floor

A Flat, Warm, Moisture-Resistant Base

The floor is constructed from SIPs panels laid directly onto the ground screw framework, creating a perfectly level, structurally rigid platform before anything else goes up.

Because the insulation is integral to the panel — not fitted separately — there are no cold bridges, no sagging mineral wool and no gaps for moisture to exploit over time. The floor stays warm in winter and doesn't flex underfoot.

Integral insulation — no separate layer required
Rigid — no bounce or flex underfoot
Moisture-resistant OSB facing on both sides
Sits level on ground screw framework
Floor SIPs construction
Wall SIPs construction
02 — Walls

Strong, Quiet and Thermally Efficient

SIPs wall panels are lifted into position and secured to the floor platform. Vertical timber battens are fixed to the exterior face of the panels, creating a ventilated cavity behind the cladding and a channel for services.

Internally, plasterboard is bonded directly to the panel face, followed by a skim plaster finish. Because the panel is the structural element, there are no internal stud walls consuming floor area — your room dimensions are your usable dimensions.

SIPs core provides structure and insulation in one
No internal studwork eating into floor space
Significantly better soundproofing than timber frame
Plasterboard bonded directly to panel face
03 — Roof

Properly Insulated. Properly Guaranteed.

The roof uses SIPs panels of at least 5 inches thickness — substantially more insulation than most garden room builders specify. A gentle fall is built in to shed rainwater, and the entire deck is covered with EPDM rubber membrane or metal panel roofing.

Both systems carry a 20-year guarantee as standard. We never use felt — it's the most common failure point in cheap garden rooms, cracking and lifting within a few years. We won't fit it.

Minimum 5" SIPs — superior thermal performance
EPDM rubber or metal panel — 20-year guarantee
Built-in fall for rainwater drainage
Felt never used on any Green Rooms build
Skylights available as an upgrade
Roof SIPs construction

SIPs vs Timber Frame

SIPs Timber Frame
Insulation Integral — no gaps Fitted separately
Thermal bridges None At every stud
Soundproofing Superior Poor
Floor space Full room dimensions Lost to studwork
Build speed Faster Slower
Long-term No settling or gaps Can shrink and gap
SIPs panel cross-section

Want to See a SIPs Build in Person?

Visit our showroom in Lyne, Surrey — walk around a completed garden room, touch the materials and ask us anything.

Visit the Showroom Book a Free Site Visit