The Damp Proof Membrane is lying flat and relatively smooth !
We started early again (8:30am) to get the job done before the Building Control inspector came! Phew!
We put down three separate strips, cutting holes where the conduits and pipes comes through and taped all the overlapping joints (at least 500mm!)! We folded like a parcel around the doorways which was a bit fiddly but plenty of duct tape and small pieces of DPM did the trick!
We also drilled a side hole in the manhole chamber (to the rain water tank) and stuck a short piece of conduit in, to allow the pumped water pipes, electrical cable and perhaps data sensor cables into the rain tank. The height of the chamber was adjusted so that the lid will come just above the finished surface of the concrete slab!
After lunch, we mixed some high ratio concrete, one and three quarter bags chucked into the mixer, a splosh of water until it was nice and creamy and then gradually put in four buckets (100Kg in total) of sharp sand and stones ballast, mixing all the while until the mixture is just a lovely texture!!
This works out at a 2:1 ratio mixture which will provide a water tight and seal all the bases of the conduits and pipes to the DPM.
This is important as the Agilia Force concrete from Lafarge is so liquid that it can find those loose joints and flow like water underneath the plastic and produce problems! !
We finished off the afternoon by banging in plenty of stakes to hold the formwork and weighed it down with loads of concrete blocks. There is after all quite a weight of material in there and its acts much like a liquid with some sideways loading so we are making sure we don’t have a dam burst!
And finally we finished off by roughly smoothing out the remaining portions of the driveway asphalt chippings and compacted it thoroughly ready for 3 24tons lorries to deliver the concrete !
We finished about 6:30pm ! In the dark again ! O Boy!
