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Conservatory Foundations & Footings Explained
When adding a conservatory to your home, having the right foundations is essential for long-term stability and structural safety. Foundations are the solid base that supports your new space — and without them, subsidence, damp, and uneven floors can occur over time.
Even though a small conservatory under 30 m² that isn’t attached to the main house may technically fall outside standard building regulations, we always recommend foundations are included as part of the build. Foundations ensure your structure is stable, level, and built to last.
Why Foundations Matter
A conservatory may seem light because of its extensive glazing, but the weight of both the structure and the glass needs a stable base to transfer loads safely into the ground. Soil conditions, weather changes, and ground movement (from moisture changes or nearby trees) can all cause instability if there isn’t a solid footing beneath your conservatory.
Foundations:
- Prevent subsidence and movement
- Keep your floor level and weather-tight
- Support heavier structures (like solid roofs or integrated heating systems)
- Help comply with building standards when linked to the main house
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Typical Footing Depths
There’s no one fixed depth for conservatory foundations — the correct depth depends on soil type, proximity to trees or water, and the size of your structure. However, general guidance suggests:
Small conservatories: foundations should be at least around 1 metre deep
Larger conservatories & brick-based extensions: up to 1.5 metres deep or more
Foundations should reach undisturbed soil well below surface level to provide a secure footing for your build.
Preparing the Ground
Several key factors affect how conservatory foundations are prepared:
- Soil conditions: Clay, mixed, or loose soils can expand, contract or shift, requiring deeper or wider footings.
- Nearby trees: Tree roots can extract moisture from soil, causing contraction and expansion that may destabilise shallow footings.
- Existing ground disturbance: Areas previously dug or filled may need extra preparation to reach firm soil suitable for foundations.
Correct groundwork ensures your conservatory stands on firm, stable footing and helps avoid costly repairs in the future.
Professional Services & Compliance
At Milton Windows, we include foundation design and installation as a standard part of our conservatory service. We assess your site and soil conditions to determine the optimum footing depth and type. We also take care of planning and building regulations on your behalf, where required, giving you peace of mind throughout the process.
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Book your free, no-obligation quotation with one of our local expert consultants, who will:
Provide a clear and accurate quote
Share practical ideas and tailored solutions
Show you a range of product samples
Take all required measurements
