Summerhouse Bases
Poured to last.
C28/35 ready-mix delivered to your garden. From 0.75m³ upwards. With our volumetric mixers, pay only for what's poured. Instant price in 60 seconds.
The Mix You Need
C28/35 High-Strength Mix
- Mix grade
- C28/35
- Slump
- 75mm (workable)
- Aggregate
- 20mm
- Recommended depth
- 100mm
- Sub-base
- 100mm Type 1 MOT
- Typical volume
- 0.75-2.0 m³
Volume Guide
How much for your summerhouse?
Based on a 100mm slab. Most summerhouse suppliers specify a base 100mm wider than the building on each side.
6×8 ft summerhouse
1.8m × 2.4m
8×10 ft summerhouse
2.4m × 3.0m
10×12 ft summerhouse
3.0m × 3.6m
12×14 ft (larger)
3.6m × 4.2m
Why It Matters
Get this right and you won't redo it for 30 years
- A summerhouse full of furniture, people and weather still needs a base that won't sink. C28/35 at 100mm outlives the building.
- A compacted sub-base stops differential settlement, the thing that rips doors out of alignment after the first wet winter.
- DPM under the slab keeps the timber floor of the summerhouse from wicking up ground moisture and rotting the bearers.
- For a fraction of the cost of a rebuild, over-spec the base now and never revisit it.
Step by Step
How to prepare & pour
Mark the footprint + 100mm
Measure the summerhouse footprint from the supplier drawings, add 100mm margin on every side. Mark with pegs and string lines.
Excavate 200mm
Dig down 200mm (100mm sub-base + 100mm slab). Remove topsoil and any soft spots, you need undisturbed firm ground underneath.
Compact Type 1 sub-base
Whacker-plate 100mm of Type 1 MOT in 50mm lifts. The top should be level and ring solid under the plate.
DPM & formwork
Lay 1200-gauge DPM over the sub-base with 150mm overlap at any joints. Set timber shuttering to finished slab level, checked with a spirit level.
Order & pour
Use our calculator for exact m³, we include 10% wastage. Pour direct from the chute, tamp with a straight-edge, float smooth.
Cure for 7 days
Walk-on hard after 24 hours but wait 7 days before you install the summerhouse. Full cure 28 days, by then it's bombproof.
FAQ
Common questions
Do I need reinforcement in a summerhouse base?
For bases under 10m², C28/35 at 100mm without mesh is fine on well-compacted Type 1. Above 10m² or on clay soil, drop A142 mesh in on 50mm spacers.
Can I put a summerhouse on paving slabs?
Not recommended. Slabs move and channel loads unevenly. A concrete slab is 3× the lifespan and costs less than replacing a rotted summerhouse floor in 5 years.
How long before I can install?
7 days. Walk-on in 24 hours, full cure 28 days. Installation loads are fine after a week.
How much concrete do I need?
Multiply length × width × 0.1 for a 100mm slab. An 8×10 ft base (2.4 × 3.0m) = 0.72m³. Order 0.85m³ to allow for wastage. Use our calculator.
Is a summerhouse base different from a shed base?
Same spec, C28/35 at 100mm. Summerhouses tend to be slightly larger and carry more load (insulation, glazing, furniture), so we suggest 100mm minimum depth.
Can you pump into a rear garden?
Yes. If we can't chute direct, we arrange a pump as part of the booking. Reaches up to 30m+ over obstacles. Call 024 7636 1448 for a pumped quote.
Ready to order?
Instant price in 60 seconds. Next-day delivery subject to availability. With volumetric, pay only for what's poured.