Garden rooms on a sloping garden

Base options on a slope

• Ground screws: screwed in at different depths, then a level timber or steel frame on top. Little excavation, no concrete, quick. See foundations.
• Concrete pads: separate pads at different heights, a middle option for gentle slopes.
• Cut and fill with a slab: dig into the high side and build up the low side, often with a small retaining wall. The most work and cost.

The height limit on a slope

Garden rooms can be 3 m tall, or 4 m with a tiled or slated pitched roof, measured from ground level. On a slope the ground isn't one level, so the room is taller on the low side. Councils don't all measure it the same way.

Drainage

• Rain runs down the slope towards and under the room. Keep the base clear of the ground and allow air to flow underneath.
• If you dig into the slope, the cut face needs drainage so water doesn't sit against the back wall.
• Take roof water to a soakaway or drain, not onto the slope above the house.

Steps, access and deliveries

• A raised floor on the low side may need steps or a small deck to the doors. Plan them in from the start.
• Getting materials up or down a sloping garden takes longer and can cost more. Tell suppliers about the slope when you ask for quotes.
• For a room at the top of a long slope, budget for a longer cable trench. See electrics.