Thanks to advances in manufacturing processes in recent years, the humble conservatory structure has gone from strength to strength. Remaining the ‘go-to’ extension option if you require more space, light, and warmth, the questions Can you have a conservatory without foundations? and Do you need to dig footings for a conservatory? come up every now and then, and our response is always the same;

A property is only as stable as its foundations. A conservatory is an extension of your building, so foundations are essential to keep it structurally safe and sound.

Officially, conservatories are exempt from building regulations if they are built at ground level, their floor space is less than 30m², and it is separated from the house by external walls, doors, or windows*. However, modern conservatories are often built with clear access to the property or have integrated heating systems. In these cases, they fall within the same category as an extension and therefore require foundations to comply with permitted development and Building Regulations. That said, although foundations are not legally required in some instances, without secure footings the consequences can be catastrophic, so foundations are crucial.

* Correct at time of publishing

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Do you need foundations for a lean-to conservatory?

Quite simply, yes, foundations are needed for all conservatory styles – the deeper the better! Nevertheless, one of the pros of small lean-to’s and small Victorian conservatories is they typically require shallower foundations than larger, sturdier conservatory structures like P-shaped, Georgian, and Edwardian conservatories.

How deep should conservatory foundations be?

/ Small conservatories, no obstructions Large conservatories
Foundation depth At least 1,000mm At least 1,500mm

Of course, the depth of your foundations will vary according to the area’s unique ground conditions. It’s important to remember that shallow foundations are typically more vulnerable to subsidence.

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side shot in interior of conservatory

What can impact the cost of preparing my conservatory foundations?

To determine the type of conservatory foundation required, we take many aspects into account, including:

  • Nearby trees and shrubs
  • Soil suitability (loamy soil is ideal)
  • Undisturbed ground
  • Surrounding drains and sewers
  • Material weight, e.g., uPVC, aluminium, or timber.

What are the consequences of a conservatory with substandard or no foundations in place?

  • Reduced thermal efficiency
  • Condensation
  • Damp
  • Uneven floors
  • Flooding
  • Subsidence (the gradual caving in or sinking of an area of land)
  • Demolition

Can you underpin a conservatory?

If your conservatory was built without foundations or the ground has shifted, underpinning it could be an option. Varying in cost depending on a number of factors, the average cost for mass concrete underpinning is around £1,500 per m2. So, it’s important to check whether it’s cheaper to rebuild the conservatory from scratch.

When we survey your home, we will be able to investigate whether there are cheaper options available to you, e.g., Correcting tree-related subsidence issues by pruning them back.

Can you build on top of conservatory foundations?

As long as the existing foundations are deep enough and wide enough, in theory, it’s a possibility. Often an option for homeowners looking to turn their conservatory into an extension, we would need to survey the foundations before going any further.

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side shot of victorian conservatory

What are the new conservatory rules 2022?

From the 15th of June, Building Regulations are changing in England to help meet Britain’s net zero emissions targets by 2050. Focused on improving ventilation, conservation of fuel and power, and preventing overheating, the introduction of new Approved Document O will address the problem of overheating in new homes due to ‘unwanted solar gain’. So, from June, U-values for conservatories will need to be 1.5 or less to comply with new building regs. Unless it is kept separate from the house with walls and exterior doors and is not heated, this could mean having to install modern solar control glazing or reducing glazed areas in new conservatories and orangeries to meet the latest building control standards.

Alternatively, those with tired, cold, and unused conservatory spaces could really benefit from a high-performance conservatory roof replacement instead.

Refined and reliable conservatories in Devon and the South West

If your home improvement plans involve making the most of far-reaching views in Devon, it’s time to consider a beautiful, bespoke conservatory designed and installed by the Conservatory Makeovers team. Dedicated to getting the job done right without any shortcuts whatsoever, learn more about us, get a free no-obligation quote, or get in touch to discuss your specific project requirements in full with a conservatory company that truly cares.

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