How To Prepare the Foundation for a Garden House – Step by Step
A good foundation is the basis for the longevity of garden houses, literally. In our experience, an incorrectly prepared foundation is the most common cause of problems in the first year after installation. This guide explains how to get it right.
Why the Foundation Is So Important
A garden house is a wooden structure that is sensitive to moisture and uneven surfaces. Without a proper foundation, you risk:
- Doors and windows that won’t close
- Water accumulation under the floor and mould
- Wall deformation over time
- Reduced the lifetime of your home
Foundation Types for Garden Houses
There are three main types of foundations. The choise depends on the size of the house and the ground conditions:
- Gravel/rubble base: suitable for small houses (up to 15 m²). The simplest and most economical solution. Dig a 15-20 cm deep area, lay geotextile and fill with compacted gravel.
- Concrete block foundations: the universal solution for medium and large houses. Concrete blocks are placed on a compacted gravel base under each corner and every 1-1.5 m along the wall line.
- Screw pile foundation: the best solution for difficult soils (clay, high water table). The piles are screwed into the ground until a stable layer is formed.
Step by Step Preparation
- Choose a location: at least 50 cm from the fence, take into account the position in the sun and access for delivery
- Mark the area: the foundation should be 20-30 cm larger than the dimensions of the house on each side
- Ensure drainage: water must flow away from the house. If necessary, create a slight slope (1-2%) from the house
- Prepare the base: remove topsoil (20-30 cm), lay geotextile against weeds and moisture
- Level: it is the most important step! Use a laser or water level to ensure that the base is perfectly horizontal. Tolerance – maximum 5 mm per 2 m
- Install the base elements: depending on the type of base chosen, install the blocks or gravel and compact thoroughly
Common Mistakes
- Skip the geotextile – without it, weeds and moisture quickly come into contact with the timber
- Insufficient compaction – gravel or earth settles over time and the house starts to sag
- Foundation directly on the ground – the timber should never be in direct contact with the ground to avoid rotting
A properly prepared foundation ensures that your garden house will last for decades without problems. If you are not sure about the soil conditions or the best solution for your situation, consult our experts. We will help you choose the right type of foundation and give you detailed instructions.
