Ordinary garden rooms are timber-frame with mineral wool between the studs. Arden & Oak walls are structurally different. Here's what's actually inside the wall, from outside to inside.
The layered build-up
- External cladding — cedar, thermowood, Accoya or charred timber (typically 21 mm)
- Ventilated cavity — 25 mm treated batten, cross-battened for airflow
- Breather membrane — vapour-open, weather-resistant
- insulated panel — 15 mm OSB + 142 mm PIR + 15 mm OSB (172 mm total)
- Service void — 25 mm batten cavity for cables and switches
- Vapour control layer — sealed at every joint
- Interior lining — 12.5 mm plasterboard or 18 mm ply with skim finish
- Total wall build-up: approximately 235 mm from outer skin to inner face