Any options for over 600mm of infill?

[CH_18]

Hi everyone, first time poster ? 

 

We are due to start groundworks on our build in the next few weeks. We planned to go with a ground bearing slab but after digging some test holes found that theres approx 700mm of top soil that needs to come off he whole plot before starting.

 

To level off the site, the developer had dug out from the high level side of the site and dumped it all on the low side to level it out. (Our plot is in the low side of the site.)

 

From the test holes we worked out from the top of our foundations to our finished floor height will be 1.2m. With 600mm of hardcore in fill that leaves 600mm to be made up with concrete and insulation. Are there any other options to build up the 600mm? I keep reading about EPS blocks, could that be an option? Or is the only option (sounds probable) a beam and block suspended floor?

 

Ideally we'd want to go down the slab route if possible. Having a cold breeze under the house doesn't sound very thermally efficient to me? 

 

Thanks in advance ?

[nod]

Hi 

and welcome 

We where in a similar position While the plot looked flat we also had 600 mil of spoil from a previous build that had been grassed over

All to be removed before we broke ground 

We used strip foundations with a BB floor

This wasn’t particularly expensive and hassle free 

[Mr Punter]

Crushed concrete is probably the cheapest way to make up the levels.  It needs to be spread in layers and very well compacted..  You could put a 100mm layer of type 1 on this an it will wack down nice and flat.  EPS is fine as insulation, then concrete on top.  Did you consider doing a passive slab, which is a reinforced concrete raft sitting on insulation?

[ProDave]

That's probably a similar gap that we would have had to make up, and for very similar reasons.  I went for strip foundations and a suspended timber floor.

[CH_18]

Thanks for the replies everyone ?

 

Yeah I think that's the way we'll be forced to go, strip foundation with b&b floor, followed by 150mm insulation plus screed.

 

Could one option be to back fill with 600mm hardcore, put 50mm of sand in, then 300mm EPS blocks, then approx 200mm concrete? That would get us to around the magic number of 1.2m? Or would that build up not be structurally sound?

[LA3222]

I am right now doing my founds.  Dug out 800mm and put 500mm of stone back in.  Had to go to 1300mm in a few places as the ground was soft. 50mm of sand on the stone followed by 300mm of EPS.

 

I had already dug out a wedge of the plot prior to this as it slopes gently.

 

Got rid of 500t of muck and brought 300t of stone back in.

 

Of the top of my head I've had about 1000t of muck/concrete removed so far at £7.50/t.

 

Such is life ?‍♂️

 

I could have chucked some strip founds in but wanted to go for an insulated slab.  You can do what you like really, just depends on your appetite to pay for the muck out and stone back in?

[Oz07]

Unsure how this works really. Usually founds deeper than 1500 or if making up ground of over 500mm (I think) bco's want suspended floors unless otherwise agreed. Does eps count as making up probably not. Also probably cheaper than stone. What's to stop 225mm stone and 450mm eps for instance?

[CH_18]

19 hours ago, Oz07 said:

Unsure how this works really. Usually founds deeper than 1500 or if making up ground of over 500mm (I think) bco's want suspended floors unless otherwise agreed. Does eps count as making up probably not. Also probably cheaper than stone. What's to stop 225mm stone and 450mm eps for instance?

 

I would like clarification on this also.

[Carrerahill]

On 04/02/2020 at 09:53, CH_18 said:

Hi everyone, first time poster ? 

 

We are due to start groundworks on our build in the next few weeks. We planned to go with a ground bearing slab but after digging some test holes found that theres approx 700mm of top soil that needs to come off he whole plot before starting.

 

To level off the site, the developer had dug out from the high level side of the site and dumped it all on the low side to level it out. (Our plot is in the low side of the site.)

 

From the test holes we worked out from the top of our foundations to our finished floor height will be 1.2m. With 600mm of hardcore in fill that leaves 600mm to be made up with concrete and insulation. Are there any other options to build up the 600mm? I keep reading about EPS blocks, could that be an option? Or is the only option (sounds probable) a beam and block suspended floor?

 

Ideally we'd want to go down the slab route if possible. Having a cold breeze under the house doesn't sound very thermally efficient to me? 

 

Thanks in advance ?

6F2/6F5 - call demolition companies that crush and or the big building waste skip places. I got 10 tons of 6F5 for £45.00

 

FYI: 6F2 is basically crusher run made on site, and 6F5 is crushed elsewhere and brought it.

 

However, I would probably redesign to save removal or material and import of material. 

 

 

 

 

 

 

Edited February 7, 2020 by Carrerahill