The past 2 weeks has been focussed on drains and backfilling. David and Martin of Insul Hub have been with us all this week operating the machinery. Getting to the back of the house is tricky due to the sloping ground and the size of the hole that we had to excavate for safety reasons. As we were unable to bring in a tower crane, which would have made the job straightforward, Insul Hub has used conveyor belts for the first time. This allows the aggregate to be dropped at the front of the building and conveyed to the back where it can be placed in the right position to backfill. This has worked well but is slower than the crane would have been.
Having established the waterproofing on the outside of the basement wall, we now have a myriad of drains!
First, at the lowest level, we have 2 deep drains designed to remove any water that gets as far as the basement walls. These are membrane-covered “leaky” pipes, which run along the back and down both sides into the surface water drains.
Second, immediately above the leaky pipes, we have the foul drainage. Due to the design of the services within the building, we have only 2 foul drains, one running down the centre of each side of the building. These have been installed, connected to the main sewer in the road, tested, and approved by Building Control.
On top of these, and closer to the finished ground level, we have the surface water drainage which will take rain water from the roof and the 2 balconies. These have to follow a different route into a soakaway in front of the house. However, rather than waster this “free” water, it is our intention to install a holding tank which we can use to water the garden. More about that later.
Finally, the team have been able to backfill, initially with aggregate to ensure that all the areas around the basement are free-draining. We are now half way up the basement wall all round and this should be completed early next week ready for scaffolding to be erected.
