Conservatory Construction

Strip Foundation for a Conservatory

Some conservatories will sit quite happily on a simple concrete slab base which serves both as a foundation and floor structure. However if the ground is covered by a deep layer of topsoil it is much better practice to dig trench foundation down into the natural subsoil.


Excavation of Foundation Trench

Normally the foundation trenches are excavated to 450mm wide by 650/1000mm deep dependent ground conditions.

Where an existing drain punctures a foundation the foundation must be below the (bottom of drain) and a precast lintel must be placed above the drain to ensuring that no weight is put onto the drain.

Casting of Foundations

A mass fill is normally used as this tends to be quicker and therefore cheaper. The concrete is normally finished 150mm below ground level.

It is always generally wise to knock 350mm x 10mm steel pins into the side of the trench at 600mm centers which should be levelled with a spirit level so you will know when the concrete in the trench is at the correct height.


The damp proof course needs to be a minimum of 150mm above outside ground level to meet UK planning regulations. Ideally, it should be at the same level as the existing building.


Raft Foundation

Raft foundations can be a suitable alternative if traditional strip/trench fill foundations cannot be used. They are not suitable in all cases so specialist advice should be sought.


Rafts are most often used these days when the ground is unstable or a normal strip foundation would cover more than 50% of the ground area beneath the building. In areas where mining has occurred there may be areas of movement in the ground which would require a raft foundation.

A raft foundation spreads the weight of the building over the whole ground floor area of that building. The raft is laid on a 150mm of hardcore, or scalping bed. Rafts are most suitable when the ground is of good load bearing capacity and little work is required to get a solid foundation.



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  2. When building your own conservatory, it must have a good foundation. It would be better if you know someone who could help you with the right measurement. I suggest that you search over the Internet to look for more conservatory designs. If you want to know more about cheap conservatories, you may click this to read more related blogs.

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