Floor build up

[mayurw]

I'm planning to install UFH on the ground floor at my house which currently has a suspended wooden floor. I have around 300mm void under the floorboards with a concrete base. Assuming I go with a 75mm screed to fill, my question is what should I fill it with as I would like to do this myself if possible? Could I fill it with just insulation or would it be advisable to go with hardcore, sand blinding, dpm, insulation and then Screed?

Any advice appreciated

 

[tomfe]

Insulation is light and easy to move but more expensive than infill.
225mm of expanded polystyrene is not a too daft amount to put in.
Either one is valid it's just up to you, I know which one I'd do.

 

[Blagard]

With a wooden floor your concrete base is most likely just an oversite concrete, not a concrete floor. it may or may not have a DPM but in any event that would be bridged by your new solid floor set at a higher level. So ultimately you are looking at hardcore/sand blinding/DPM /insulation / concrete floor and then screed. The DPM needs to be tied into the wall DPC

 

[Taylortwocities]

Are you thinking of wet UFH or electric?

 

[mayurw]

Thinking I might just go down either the retrofit or in-between joist method as this sounds like I would need to build a peoper Base. It's the water UFH system I'm thinking of going for

 

[tomfe]

build a peoper Base.

OO a peoper base
You'll probably find the over site is good enough, if want to check drill a hole in it.

 

[mayurw]

OO a peoper base
You'll probably find the over site is good enough, if want to check drill a hole in it.

Might do that, thanks.

If say I find 3-4 inches of concrete, is that sufficient to lay say another 4 inches on top of that and then go DPM, insulation and screed?

 

[mayurw]

How much would one expect to pay for around 4m3 of concrete these days? Can be ready mixed or mixed onsite.

Thanks

 

[Blagard]

How much would one expect to pay for around 4m3 of concrete these days? Can be ready mixed or mixed onsite.

Thanks

I think at least an area post code might help get some reply on that I have no idea myself what London prices are like.

 

[mayurw]

Sorry, it's north west London

Thanks

 

[liam86]

Replacing the whole ground floor would be a big messy job, and sounds like you have a lot of void to fill with material which will become expensive. Also, suspended floors will be ventilated to help stop damp creeping from foundations which is probably useful in an older home. You could retrofit electric UF heating, in my limited experience suppliers prefer to recommend electric for smaller jobs and it can sit between joists. This and new/more insulation could do a good job. Alternatively, what about investing in some nice radiators!

 

[tomfe]

4m3 of concrete will be around £500 ready mixed.
That's a fair amount of concrete, 40m2 of it at 100mm.
You can lay ducting in the floor if you need to ventilate another rooms floor void however make sure it's below your insulation level. You could also just add extra air bricks on the external walls instead.

But really just drill a hole see how deep your oversite is. Then if it's 4" thick lay a DPM and stick 225mm of eps in it, that'll cost about £400 for a 40m2 floor. Then lay a thin layer of polly down (to stop the eps from lifting) then do your wet underfloor heating clipped to the eps through the polly. Then get someone in to screed it. I bet you could have it down over a weekend and get the screen done the next couple of days. Probably about £2/3k all in.

 

[mayurw]

Looks like I have between 3-4" of concrete. Happy to go down the 225mm of eps if people think that would be ok? I'm planning on finishing the floor with tiles if that makes a difference?

 

[mayurw]

4m3 of concrete will be around £500 ready mixed.
That's a fair amount of concrete, 40m2 of it at 100mm.
You can lay ducting in the floor if you need to ventilate another rooms floor void however make sure it's below your insulation level. You could also just add extra air bricks on the external walls instead.

But really just drill a hole see how deep your oversite is. Then if it's 4" thick lay a DPM and stick 225mm of eps in it, that'll cost about £400 for a 40m2 floor. Then lay a thin layer of polly down (to stop the eps from lifting) then do your wet underfloor heating clipped to the eps through the polly. Then get someone in to screed it. I bet you could have it down over a weekend and get the screen done the next couple of days. Probably about £2/3k all in.

I'm assuming you're referring to polythene as polly?

 

[mayurw]

went to Grand Design Live last week and spoke to a guy about a lightweight block and beam system. Is this something I could use?