How Important are Conservatory Foundations?

Most people assume that a conservatory, much like a window or door, is built from the ground up. In actuality, a conservatory is like an extension of a house, and as such it needs the same structural stability that your house – or indeed any building – needs.

Conservatories are only as strong as the foundations they are built upon. They can subside if they aren’t on a secure footing. Even single-storey extensions and conservatories require deep foundations to stand strong for as long as possible. That means having to dig down to a considerable depth and then constructing a base from essential elements.

Before you dig out the foundation, make sure that you have the right planning permission for the build, if necessary. Also be sure that your installer has the skills and experience required to create a solid foundation.

How Deep Should the Foundation Be?

There are several factors that go into determining the necessary depth of the conservatory foundation. Things like the condition of the soil, any nearby trees, rivers, and train lines can all affect how you should prepare ground before staring construction. Another thing to check for is any obstructions that have to be avoided, such as a drain cover.

In terms of averages, we would recommend that you dig at least a metre deep and then fill the trench with concrete for maximum strength. The ideal depth is closer to 1,500mm tough, which is the ideal depth for a regular extension. That is because modern conservatories and orangeries are made from more substantial materials.

A brick cavity wall for the conservatory is built onto the foundation, which should be insulated with 75mm of wall insulation.


FREE Conservatory Advice & Quotes


Complete Glazing Birmingham offer free advice and no obligation quotations, get in touch with us today to get your questions answered.

Piled Foundations

When dealing with loose soil conditions, it may be necessary to reinforce the foundation using piles. These steel rods break through the loose soil and are driven into the ground to properly distribute the weight of a conservatory on loose soil to establish a solid foundation.

Conservatory Base

A conservatory base is made from a layer of ‘hardcore’ which is covered in a layer of sand. Hardcore refers to a solid material, such as stone, that has been taken and crushed and laid out on top of a concrete foundation to form a level base. It’s recommended that you have at least 150mm of hardcore within the foundations of your conservatory. The compacted hardcore is laid out over a layer of sand to establish an even surface.


This special layer of damp-proof material covers the base to prevent moisture from the ground below the foundations from seeping into the foundation.

Floor Insulation

A thick insulation layer goes on top of the damp-proof layer to ensure heat doesn’t go down through the floor. We recommend that you use an insulation layer between 70-100mm thick for best results.

Smooth Screed Floor

Finally, a smooth layer of concrete is poured over the base. It is reinforced with steel before the floor screed is applied. This is made from cement or a combination of cement and sand. Screed is “smoothed” into place with a leveling board over a raised timber bed. This layer helps ensure that the conservatory floor is flat and smooth.

After all of this is done, the conservatory is ready for wooden flooring, tiles, or carpets.


Complete Glazing Birmingham
Unit 130, 180 Sherlock Street
Birmingham, B5 7EH
0121 405 1058
Mon to Fri 8:00am - 6:00pm
Weekends 8:00am - 4:00pm



About Us

Complete Glazing Birmingham is a sister company of Mainstream Windows a local double glazing, orangery and conservatory installation company based in Birmingham servicing Solihull, Knowle, Sutton Coldfield, Bromsgrove, Leamington Spa, Warwick and Evesham.



© 2019 Complete Glazing Birmingham. All Rights Reserved.