So its been a busy last few months! After appointing a local contractor to excavate the basement and construct the reinforced concrete slab and walls we finally started excavating on the 27/03/23. The basement is approx. 31m x 7m x3m deep so there was quite a lot of spoil to remove especially as there needed to be 1m working area around this and the sides had to be stepped for safety. Access onto the site is also very tight and made worse by the build of another house directly opposite the end of my drive starting at almost exactly the same time. Excavation took about three weeks; we left several hundred tons of spoil on site to backfill around the basement walls.
The next job was to install the under-slab drainage and sewer pump. As the only sewer we can connect to is some 7m higher than the bottom of the basement as sewage flows into a holding tank and is then pumped up to the public sewer. This meant digging a further 3m down to install the pump under basement slab along with all the foul drainage from toilets etc in the basement. The pump is encased in concrete to stop it floating/ bulging – this is not the easiest task to do as the depth of the concrete has to be restricted when being poured to stop the chamber collapsing in. A week after putting down sand blinding / shuttering or so later the base looked like this:
The black pipe on the right is the line that goes up to the public sewer. Here’s hoping that a) the sewers are all in the right place (hopefully I can still manage to set out) , b) there’s no leaks and c) the reassuringly expensive pumps are up to the job – as it all get buried under the concrete slab repair / amendments will not be possible without major trauma.
After a specialist contractor laid a waterproof membrane on the sand blinding the reinforcement for the base c/w starter bars for the wall reinforcement was installed and the 300mm deep water proof concrete base poured. This was a nard day’s works for the lads actually doing the work as there was about 70m3 of concrete – 12 lorry loads (we can only use 6m3 lorries due to the tight access)
Reinforcement for the walls was then installed along with the all important water bar at the base of the walls to stop ingress of water (fingers crossed!) The formwork ‘pans’ were also positioned to form the 300mm basement walls. This was done in two parts due to the amount of formwork needed and the cost of hiring it. Eventually we ended up with what looks like a large swimming pool – hopefully it would actually hold water once the waterproofing to the outside is complete; hopefully it doesn’t rain heavily for the next 4 or 5 months so doesn’t fill up but I think this is very unlikely so I might need a temporary pump.
Away from site the structural steelwork installers suppliers, the beam and block concrete floor suppliers / installers and the brickies are all lined up – their work all interconnects with each other so no doubt liaising between them will cause a few headaches. This is all due to start in early July once we’ve installed a drain / clean stone around the base of the wall and backfilled to level with the stored excavated material.
By the way, all those folks on Grand Designs aren’t putting it on – it’s hard work and bloody stressful building your own house and I suspect it’s not going to get any easier. Thanks to having a great contractor to work with everything has gone reasonably smoothly so far – long may it continue! I’m now off on a long weekend to the 100th anniversary running of the Le Mans 24h race so it can be put to the back of my mind for a few days.
This blog article is part of an on-going series. CLICK HERE TO READ PART 1 AND PART 2
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