Conservatory Base Construction
We have been asked many times how a conservatory base should be constructed. We have compiled a basic conservatory base construction guide which should cover the majority of cases and answer your questions. The construction of a typical conservatory base is very similar to that of an extension to your house.
It is a general belief that; because a conservatory is lighter than an extension the foundation does not have to be very deep. This is not necessarily correct.
Firstly it is not possible to know precisely how deep the foundation will be until the ground is excavated and inspected for any 'made up areas' - this is where earth has been placed on existing ground.
Therefore it will be necessary to excavate a trench through this layer into load bearing ground. By doing this you will ensure that the conservatory has a good foundation base, as we expect that you do not want to wake up one morning to find your conservatory at the bottom of your garden!
Normally foundation trenches are between 650 - 1000mm deep.
The other factors which determine the foundation depth will be tree roots, drains and services.
Reduction of Ground Levels
The areas where your conservatory is to be built should have any hard materials removed, i.e. patio, concrete slab, etc. and any vegetation soil removed to an approximate depth of 150mm.
Excavation of Foundation Trench
Normally the foundation trenches are excavated to the following dimensions. (Ready to receive a mass concrete foundation) 450mm wide by 650/1000mm deep dependent upon ground conditions.
Casting of Foundations
The foundation trench can now be concreted. A mass fill is normally used as this tends to be quicker and therefore cheaper. The concrete is normally finished 150mm below ground level.
Oversite and Foundation Construction
It is always a good idea to knock 350mm x 10mm steel pins into the side of the trench at 600mm centers leveled with a spirit level so you will know when the concrete in the trench is at the correct height.
Oversite and Foundation Construction
100mm Concrete slab reinforced with a 142 steel mesh on 50mm sand blinding, on 250 micron damp proof membrane on 150mm (min) well consolidated clean hardcore.