Groundworks & Bases for garden buildings
Proper ground preparation is essential to ensure your Chart Garden Building remains stable, level and protected from ground moisture. Garden rooms, summer houses and pavilions require a solid reinforced concrete base, while gazebos simply need a flat, level surface with staddle stones beneath each upright post.
Why Groundworks Matter
Every Chart Garden Building is crafted from high-quality timber, and its long-term performance depends on keeping the structure stable, level and clear of ground moisture.
A properly prepared base:
- Keeps the building level and structurally sound
- Prevents twisting, settling or movement over time
- Protects against rising damp
- Allows for accurate and efficient installation
- Extends the overall lifespan of the building
Without a suitable foundation, even a well-built timber structure can experience avoidable issues.
Groundworks for Garden Rooms, Summer Houses & Pavilions
All enclosed and static buildings in our range — including garden rooms, summer houses and pavilions — must sit on a solid, level concrete base.
Recommended Base Specification
The typical build-up should include:
Excavation
The site should be dug out to the required depth and footprint, removing all topsoil and organic material.
Compacted Sub-base
A layer of hardcore or crushed stone should be laid and thoroughly compacted to create a stable foundation layer.
Damp-Proof Membrane (DPM)
A damp-proof membrane should be installed above the sub-base to prevent ground moisture rising into the slab.
Reinforcement Mesh
Steel reinforcement mesh should be positioned within the slab to improve strength and reduce the risk of cracking.
Concrete Slab
High-quality concrete should be poured to the appropriate depth and finished perfectly level. The slab must be fully cured before installation.
Accuracy is critical. The finished base must be square and level to ensure correct assembly and long-term structural integrity.
Brick Course
A single course of brick should be installed as per the base plan. This will:
- Raise the timber structure slightly above surrounding ground level
- Provide additional moisture protection
This detail depends on site conditions and overall project design.
Groundworks for Gazebos
Gazebos are open-sided structures and do not require a full reinforced concrete slab.
Instead, they should be installed on:
- A flat concrete surface
- Paving slabs
- Tarmac
- Or a well-compacted stone surface
Each upright post must sit on a staddle stone or similar pedestal support. This lifts the timber clear of the ground, reduces moisture contact and promotes airflow beneath the posts.
The key requirement is a stable, level surface to ensure structural integrity.
Preparing for Installation
Before your installation date:
- The base must be complete and fully cured
- The area should be clear and accessible
- Final levels should be checked carefully
If you are working with a contractor, we can provide detailed dimensions and base specifications for your chosen building to ensure everything is prepared correctly.