Can you use steels?

10 minutes ago, Dreadnaught said:

 

Interesting.

Is concrete board the same as cement fibre board?

What type of insulation did you use?

Were the joists timber I-beams?

VPL, is that a VCL?

 

 

 

Sorry meant Cement fibre board. Solid spruce joists, oversized and at close spacing so very solid. Yep VCL. Insulation will be a 'soft' breathable type. The stuff you stuff between joists. Didn't fancy foil insulation as want to make sure floor can get rid of condensation

 

6 minutes ago, Ferdinand said:

Can you use steels?

 

I can't think why not. A steel ridge beam superficially sounds like a splendid idea. I will investigate.

no reason you couldn't use a poured thin screed over the timber deck either. Our FF is 50mm hemihydrate over caberdek , on 254 pozis @ 400ctrs, with a span of 4.7m. It's impressively stiff and quiet.

I was about to post separately on this, but it might be worth exploring the OP Deck system, or something similar -

 

https://www.cdi-icm.co.uk/system/op-deck/

 

Looks quite interesting as a solution, they don't include loadings, but it's essentially a cross between steel SIPs and ICF to create a suspended, insulated rib slab. They say it can free span 10m so could span from a precast concrete or steel ring beam.  The depth is variable depending on insulation levels but a  minimum of 254mm  Avoids the need for a 50mm concrete oversite that you get with a timber ground floor and from the video it looks quite straightforward to DIY install once the supporting piles are in place. 

 

Because it's used for car parks and the like I'm assuming that you could build the timber walls straight off the slab to avoid cold bridging but would need to check with their technical dept / engineers. 

 

Has anyone else considered using this sort of hybrid suspended passive slab solution?

10 hours ago, dpmiller said:

no reason you couldn't use a poured thin screed over the timber deck either

 

Thanks @dpmiller, that's useful information. Another option for me to consider. Very good.

2 hours ago, Archer said:

it might be worth exploring the OP Deck system

 

Thanks @Archer. By coincidence yes I did notice that system this very weekend when doing some google searching. Yesterday, I sent them an email enquiring for more details. 

Edited February 2, 20206 yr by Dreadnaught

Thanks Dreadnaught, I'd be interested in what they come back with if you get a response. We used a cementboard faced SIP system to build our extension and were originally considering a company called Quickbase Foundations to build off. They use screw piles with a structural SIP as the ground floor (ie. Blockwork or timber frame constructed directly on top of the panel floor. I got talked out of it by our builder in the end but wish I hadn't listened to him. It's a good system but seems to be suitable for 1 storey buildings only. That's why the OP Deck interests me - looks like a similar idea but more robust maybe. Good luck with whatever you go for!

Thanks @Archer. I hadn't seen Quickbase. Had a quick look. Says "lightweight foundation system for conservatories and lightweight structures". I will drop them a line to see what "lightweight" means.

what I don't yet understand is why not do a 4:1 mix instead of 8:1 biscuit and then it has inherent strength? Might not be needed but it seems like a 'why not' scenario

On 02/02/2020 at 21:38, Dreadnaught said:

Thanks @Archer. I hadn't seen Quickbase. Had a quick look. Says "lightweight foundation system for conservatories and lightweight structures". I will drop them a line to see what "lightweight" means.

Not a house ... beams aren’t big enough and their screw piles are really low rated. 

On 01/02/2020 at 15:54, Dreadnaught said:

 

I have learnt that "no dig" really means "don't dig very much" so I can probably dig down 200mm or so when I am levelling the site. 200mm will take the heave-protection CellCore HX-S at least.

If so, stick with the insulated raft as intended. 
Load shifting E10 heat into the slab, to go all electric, would be less attractive without such a capacitor. 
To burn gas and heat via such an emitter, eg with such a short thermal time constant, would need a ‘large’ buffer tank, vs the slab + electric which would not so much so.

You’d probably get away with a small low loss header / hydraulic balancer if you go Willis now and ASHP retrospectively fitted ( if deemed necessary later down the line ).