Digging up solid floors

[Doggit]

Good reasoning Nozzle, let us know the results

 

[Nozzle]

Updates, huzzah:

I've had three firms over to look at moving the job on, one estimate returned so far (prohibitively expensive) and also a number of different approaches have been proposed to me.

a) Cut/dig up the remaining 100mm concrete floor, remove the "pebbles" that currently constitute the hardcore layer, dig down a further 100mm (by hand), insert replacement DPC, relay hardcore, re-pour 100mm concrete floor, 100mm celotex, further DPC layer, UFH and 75mm screed

b) Cut/dig up the remaining 100mm concrete floor, remove the "pebbles" that currently constitute the hardcore layer, replace with well compacted type 1 and sand layer, insert replacement DPC, 100mm celotex, further DPC layer, UFH and 75mm screed

The first option is effectively replacing the current floor with a similar arrangement 100mm deeper down, the second option is clearly much less moving materials about but doesn't have the initial tough concrete supporting everything else.

Is either option just as good?

Nozzle

 

[pilsbury]

DPC (course) or DPM (membrane)? Why 2 of them?

 

[Nozzle]

The first one because the currently installed one will be destroyed/perforated. The second, because as I understand it they're used to stop the screed running all over the place. (Copper pipes will be wrapped, but also this second DPM stops screed coming in contact with copper)

I might well have used the terms DPM and/or DPC incorrectly.

Nozzle

 

[pilsbury]

Thanks for the explanation. Might be doing something similar soon. I assume you're going for a pumped self levelling screed?

 

[tomfe]

b) Cut/dig up the remaining 100mm concrete floor, remove the "pebbles" that currently constitute the hardcore layer, replace with well compacted type 1 and sand layer, insert replacement DPC, 100mm celotex, further DPC layer, UFH and 75mm screed

You can't do that. You need a structural layer somewhere so you'd have to use concrete or a structual screed( if that exists).

 

[Doggit]

What depth have you gone down to nozzle

 

[Nozzle]

You can't do that. You need a structural layer somewhere so you'd have to use concrete or a structual screed( if that exists).

The fella metioned the screed being, 24N strong as opposed to the concrete builiding block I happened to have lying there for his example at 7.5N and that it is pumped in through the window, and that it is different to the stuff that has fibres put in it.

I don't recall the name though, but do these specs ring any bells with you? I hope is written quote might say.

Nozzle

 

[Nozzle]

What depth have you gone down to nozzle

At the moment, it's still only the tiles and screed gone leaving 100mm slab still to cut up. Beneath this slab is a layer of DPM and then pebbles, unknown depth.

Nozzle

 

[John D v2.0]

The fella metioned the screed being, 24N strong as opposed to the concrete builiding block I happened to have lying there for his example at 7.5N and that it is pumped in through the window, and that it is different to the stuff that has fibres put in it.

I don't recall the name though, but do these specs ring any bells with you? I hope is written quote might say.

Nozzle

Presumably that refers to the compressive strength, concrete is very good in compression but not so much in tension (although there will be a correlation!), hence why we put rebar in pcc lintels to stop them cracking.

 

[Nozzle]

Could I expect a slab of this particular screed, layed on nothing more than celotex, layed on nothing more than compacted MOT type 1 with layer of sand, to crack through tension?

Nozzle

 

[sambotc]

What height do you have to work with? I'm guessing around 70-80mm?

You could look at 50mm insulation with a floating gypsum based dry screed underfloor heating board (18mm), thin leveling screed over the top and carpet. This would give you decent results as the board and screed has some thermal mass, plus a lower build up and leave the existing slab as is.