Self Building two in North Wiltshire

Very similar approach to our build - sub-structure with MBC frame on top.

 

We also went with shuttered concrete - out team did all the steel work first then built the shuttering, they explained that the concrete needs to go off for a good few days before new concrete can be cast against it so we had a similar 'staggered' wall pour with 1m gaps between them which were poured last. You should have vertical water bar in these sections also.

 

Is the water bar channel full of water? Our guys were made to dry it out with a blow torch before using a mastic to hold the waterbar in place (Sika products) the rep, who issued the warranty, even came out to check this and they sent him photos every day from site.

 

They also used nifty expanding rubber plugs to seal the bracing holes, effectively a rubber bung on a thread that is screwed in to compress and expand the bung. Then cement to seal the hole. 

Its really good to see the progress and how it all goes together.

 

One thought i have is the shuttering walls look very labour intensive, which i can imagine sends the costs up.

 

Did you consider pre-cast panels like below?

 

https://www.jpconcrete.co.uk/precast-cast-in-retaining-wall/

 

i am wondering if the materials may cost more, but in terms of labour it actually works out cheaper.

Edited December 2, 2019 by Moonshine

1 hour ago, Moonshine said:

Its really good to see the progress and how it all goes together.

 

One thought i have is the shuttering walls look very labour intensive, which i can imagine sends the costs up.

 

Did you consider pre-cast panels like below?

 

https://www.jpconcrete.co.uk/precast-cast-in-retaining-wall/

 

i am wondering if the materials may cost more, but in terms of labour it actually works out cheaper.

 

Yes, formwork build & placement is quite labour intensive. 

 

With some thought, the same form can be reused on a build (depends on complexity of design) - for us, the shape of our basement allowed the contractor to build one pair of forms (inside and outside) that built a corner with a window and they were able to use it a few time before re-configuring it.

 

Pre-cast is probably less labour and possibly cheaper materials, but I was not able to find a waterproof version so I never costed it out. If I had gone this way then I would have had to put external tanking (as I am doing now) and also an internal tanking / drainage membrane. You need two  of three, forms of waterproofing in habitable basements (external tanking, waterproof concrete, internal tanking/drainage). I have a real aversion to internal drainage as it seems like an admission of failure if you let the water in and then pump it out. The other two options were Glathaar (German offsite precast) that are eye wateringly expensive, plus they dont do the dig - just the panels. Or ICF which would have worked out well, but we have a very odd insulation setup that would have made it tricky. Plus I wanted to use our contractors and they are singularly unimpressed by ICF - though they are never very clear on why.  The waterproof concrete on its own in likely sufficient, especially as we are out of the ground at the front so have low hydrostatic pressure, and the external membrane is just another of those 'belt and braces' features to keep the BCO happy and give us a 20 year warranty.