Ready for the concrete raft!
March 25, 2014
It is often hard to select sustainable materials for ground bearing constructions due to the necessity for adequate protection from ground water; we wanted to do the best we could here by using the Isoquick insulation and a recycled membrane.
We decided to use the EcoMembrane for it's 'green' credentials: it is made from 100% recycled polythene and manufactured in the UK. it is suitable for use in installations like this, where it is below a concrete slab but where there is no direct hydrostatic pressure from the ground due to the separation provided by the insulation.
This was installed on Monday, along with the sea of mesh reinforcement! The mesh reinforcement will help to resist cracking in the slab when the internal load bearing walls are constructed, and the loads from the structure are dissipated through the raft foundation to the ground below, so it is an essential part of the construction, particularly as the slab surface will be our finished floor surface!
Then today the holding down straps were installed and held in place to the mesh using tying wire ready for the next stage....
We also decided to insulate around the soil pipes as they come up through the slab in a 'belts and braces' approach to continuing the thermal envelope and to counter this otherwise cold column of air that will rise through the building. We used a water proof Armaflex insulation, which is dust free, fibre free and CFC free with an ODP of zero. This expensive proprietary insulation will be cut off flush with the slab to allow the airtightness grommet to be fitted and then we can use a cheaper flexible fibre type of insulation around the pipes above the slab level, which will also help with acoustic performance.