Planning a garden room: permitted development, foundations, and lead times
What you can build under permitted development, how our garden rooms are engineered for year-round use, and a realistic 12-week timeline from survey to handover.
Do you need planning permission?
Most garden rooms fall under Permitted Development in England, provided the building is single-storey, has an eaves height under 2.5m if within 2m of a boundary, and takes up no more than 50% of the garden area alongside any other outbuildings. The rules tighten in conservation areas, AONBs and on listed properties.
We prepare a permitted development compliance statement with every project so you have written evidence for a future buyer's solicitor. Where planning is needed, our design team handles the application.
Foundations and build-up
A garden room designed for year-round use is not a shed with better cladding. Our specification uses a screw-pile or reinforced concrete raft foundation, a fully insulated timber frame achieving a wall U-value of 0.18 W/m²K, an EPDM warm-roof, and A-rated glazing throughout. The floor is insulated to the same standard as a modern extension.
The result is a room that holds heat in January and stays cool in July, with no condensation, no cold spots, and energy performance closer to a well-insulated home office than a converted outbuilding.
Typical timeline
From signed contract to handover, most garden rooms take 10 to 14 weeks. Two weeks for detailed survey and technical drawings, four to six weeks for factory manufacture, one week on site for base and shell, and two weeks for interior finishes and electrics. We hand over a single detailed contract with a defined completion date and scope.
Only if the garden room exceeds 30m² floor area, is closer than 1m to a boundary, or contains sleeping accommodation. Most home offices and studios fall outside these thresholds.
Yes — every garden room we build is engineered for year-round use with insulated walls, floor and warm-roof, plus A-rated glazing and full electrics.
