HomeA-Z of orangeriesHow Deep Do Foundations Need to Be for a Conservatory?

How Deep Do Foundations Need to Be for a Conservatory?

Posted By : admin
Date : March 18, 2019
“How Deep Do Foundations Need to Be for a Conservatory?”

Conservatories, in most cases, do not require planning permission. However, care should be taken in the design phase. This is because, once walls are a certain height, the conservatory would be classed as an extension and would in this case need planning permission.

If the planned conservatory is at ground level and separated from the house by quality doors and windows then it will not be subject to building regulations. If the new construction’s footprint is over 30 square meters, then seek advice about permissions.

When it comes to the foundations of a conservatory, it is not always clear how deep they need to be.

Here’s some advice on conservatory foundations from Orangeries UK:

How important are conservatory footings?

As with any new structure, the conservatory will only be as strong as its foundations. Well prepared and laid foundations can make the construction easier. The foundations will avoid any future structural failings or possible subsidence.

How deep do foundations need to be?

Foundation depth depends on many factors. Good practice would be to have at least a 600mm trench in hard ground, 1000mm in softer ground and up to 1500mm in particularly fragile settings. Obviously this will affect the conservatory building costs but corners should never be cut with foundations. Good foundations will guarantee years of pleasure from your conservatory.

It is important to have professional advice on the foundation depths for your new conservatory.

How to build a conservatory?

For maximum strength, the trench should be filled with concrete, with additional consideration given to any drains or pipework exposed during excavation. Steel reinforcement can be used to strengthen the concrete over drains. A brick cavity base wall will be built onto the foundations, using concrete lintels over any pipework and insulated, as it would be in house construction.

The base within the conservatory will be formed by a layer of hardcore. It will then be concreted over, insulated and feature a damp proof membrane. The floor will then have a screed finish ready for the chosen flooring to be laid on.

Are the foundations essential?

Whilst it is possible to build a conservatory without foundations it is not generally recommended, regardless of whether there is a dwarf wall or not.

The construction’s base need not always be concrete. A wooden conservatory base could also be used. This would be constructed from heavy duty, treated timber. With a fixed outer frame, joists would be hung, braced at intervals and secured by joist hangers. A well constructed wooden base could be just as strong as concrete. This might be used to keep costs down where the conservatory has extended over sloping ground.

Another option is a metal base, constructed in a similar fashion to wooden bases. These will also have the advantage of covering awkward ground to lay a concrete base on.

There are also self build conservatory kits available. These aren’t just for simple lean-to conservatories, a confident DIYer can construct an elaborate conservatory. Care should be taken to ensure that footings and any supporting walls are constructed to the exact dimensions and specifications to accommodate the structure.


Whatever you conservatory ideas, here at Orangeries-UK we can offer support and advice for planning you conservatory. We offer a fabulous range of conservatories and orangeries to give your home the wow factor.