Bitpipe

Our contractors effectively treated the EPS slab as if it was level ground (i.e. they ignored it) and built their traditional steel lattice & formwork / shuttering on top. Slab and a 100mm kicker first and then built off this as they did the walls in sections. The kicker is necessary to hold the vertical formwork straight on the slab. Water bar on every join (inspected by the Sika rep) and Sika additive in the concrete as this was our sole waterproofing method. I don't think any serious concrete crew will entertain EPS upstands for a basement slab as they would get trashed when doing the walls - the formwork they use is very heavy duty and is craned into position for each wall pour. In my mind, EPS formwork only really works for ground level slabs or ICF where traditional formwork is not being used. For a basement you need to use traditional formwork and apply the EPS to the cast walls afterwards.

I'm re-creating a few threads from e-build where I shared experience of building my 'passive' basement, useful starting points for follow on discussions --------- The original poster was enquiring about waterproofing basements and dealing with the conflicting advice from architect and contractors. My reply: Unless you're 'in the water', which your ground investigation will reveal, warrantied waterproof concrete on its own should be sufficient.We're on undulating layers of clay, lynch hill gravel and seaford chalk so relatively free draining and don't hit water until 6m. Basement excavation was 3.5m so we went for 300mm waterproofed concrete with a land drain around the slab base to a 5m deep soakaway and a 1m wide clean stone backfill.We used an approved Sika contractor and had regular inspections from Sika during the pour, checking water bar placement, penetrations etc. We now have their 15 year insurance backed warranty against water ingress.The overall 10 year build warranty (from Ark) was satisfied by this as were BC.We have friends nearby who built close by the Thames and their basement is half submerged in ground water - they used Glatthar and were very satisfied but it wasn't cheap.We did our entire 122m2 basement for £120k with a single contractor which included demo & cart-away of existing building, excavation & muckaway and the construction of the basement itself - plus all services (fouls, rainwater, water, gas & BT duct & electric). I sourced the under slab & wall insulation separately as they weren't familiar with it at the time.Glatthar wanted about £100k for just the basement construction and we would have had to fund the groundworks separately - which would have been at least half as much again.We also designed our basement as an 'open box' with no structural internal walls so we are free to change the layout if we wish, currently having it framed out which is only costing a few £100 in labour and timber.Good luck, lots FUD surrounding basements and many of the contractors push their preferred systems (typically with additional cost) in a take it or leave it fashion but get what works best for your site and gives you the necessary peace of mind and suits your pocket.

We're being plastered too - certainly focuses the mind to get all those little jobs done as the tackers rip through the house covering everything in board! My top tip is to photograph the whole house before walls get covered up, especially where you've put in support noggins for cupboards, TVs etc - write the top and bottom heights on with a sharpie so you can find them again from the photos.

And it gets more confusing when you start to order door linings or pocket door systems to match the timber stud sizes - most are standardised around 3" or 4" stud but if you're using CLS (as MBC do for their internal framing) then you need to get something more specific or have the 4" material ripped down.

We used a groundworks buyer to finally get ours (sourced from Kay Meztler via a reseller) but it was a very large order - for just a few sheets, the shipping is going to be more than the EPS itself. Aside from the BMs, you might also want to try http://www.ccfltd.co.uk/ and http://www.encon.co.uk/ who have depots in the SE.

Hello all, as complete newbies, we started our Berkshire build last August after over a year of devouring e-build for advice. We're a fairly standard MBC passive house above ground with a passive basement below which is apparently a first. Now at the plastering stage so plenty of experience under our belt to share and still plenty of advice required! It's good to be back, Mumsnet was not doing it for me.

Welcome back Alex!

Now it's been formed it looks fine as a feature alcove, will probably stack with nice round logs as a 'homage' to the timber frame.

We've made provision for a bio-ethanol fire in a 'faux' fireplace in the living room but the smallest (and it is really small) still generated up to 3KW which is way too much. I'll probably end up fireproofing the area and have candles...