Replacing wooden joists with concrete

[tmf786]

I'm looking at installing under floor heating.

My builder has recommended to replace all of the floor joists under the living rooms x2 and hallway with concrete.

We have a crawl space under the house so there will be a lot of hardcore and concrete to fill. Probably the perimeter is about 1.3m deep x 5m wide x 6m length.

Is this the usual thing to do?

I'm concerned with the side effects of doing such work
- will it effect neighbors property?
- will it cause walls to move or become unstable?
- will it cause damp if there is no ventilation coming from under the house?
- any other pointers?

Thanks in advance

 

[DAZB]

Your builder is recommending you pour over 30 sq meters of concrete to a depth of over 4ft under about half of your house to install UFH.... change your builder !

 

[Notch7]

My builder has recommended to replace all of the floor joists under the living rooms x2 and hallway with concrete

You can’t do solid fill for that depth.

You could replace joists with bigger ones or sister existing ones then use a PUG / dry mix for your underfloor heating

or you could use aluminium platens

PUG / dry mix | Continal Underfloor Heating

Simple and cost-effective method of maximising the heat output and thermal capacity that can be lost with a suspended floor.

www.continal.co.uk

Underfloor Heating Spreader Plates – 40 Double Groove Aluminium UFH Heat Diffusion Plates – Underfloor Parts

underfloorparts.co.uk

 

[tmf786]

Thanks for the replies and details.

I should have mentioned, it wouldn't be just concrete - he mentioned there will be hardcore mot1, sand, membrane then insulation, concrete, UFH, screed, lvt


https://www.continal.co.uk/system/pug-dry-mix - this looks like a good find, thanks Notch7