Oversite for suspended concrete floor

[cwr]

Hi Folks

If I use a  suspended concrete ground floor, how best should the ground below be finished?

I know that the the ground needs cleared of topsoil, 150mm void, and periscope ventilators will be required. However, should I put down a layer of blinding, or hardcore topped with  blinding, or can I get away with leaving the earth exposed?

The area I'm in does not require any radon gas layer, and the stony clay is about 1 to 1.3m deep before bedrock is hit.

Thanks,

Chris

[nod]

Normally you would have a hardcore raked out 

Our engineer insisted we put six mtrs of concrete sloping to a drain with an anti flood valve 

I was pretty pissed off at the time 

having to do this 

But I suppose it covers All basis 

 

Pictured is ME You can’t see my face but I think I was sulking 

[scottishjohn]

well with a concrete blinding you won,t get mushrooms  or other fungi growing  in the bare soil 

so seems a sensible idea to me .

 

[nod]

2 hours ago, scottishjohn said:

well with a concrete blinding you won,t get mushrooms  or other fungi growing  in the bare soil 

so seems a sensible idea to me .

 

Yes there is that John

His reasoning was If there is ever a flood the contents of your tank would finish up under your house

Plus he did say that anything growing under there can get a bit pongy 

[the_r_sole]

.

Edited September 26, 2019 by the_r_sole

[Mr Punter]

It is normally acceptable to have bare earth as long as it is weed free.

[epsilonGreedy]

37 minutes ago, Mr Punter said:

It is normally acceptable to have bare earth as long as it is weed free.

 

 

I am watching a pro builder executive size house build near me, the beam and block floor is over bare weed free earth dug 3 weeks ago.

[scottishjohn]

57 minutes ago, Mr Punter said:

It is normally acceptable to have bare earth as long as it is weed free.

not to me It wouldn,t  be -

-but hey everybody to their own .

 

[cwr]

Thanks for the replies folks.

 

This is the floor system that I am planning on using:

 

https://www.creaghconcrete.co.uk/spantherm/construction-detail.html?p=272

 

My research so far (google) shows people doing a variety of things as above comments, from leaving the soil bare to hardcore to 100mm of concrete.

 

I spoke to someone in our local building control today (erm, suppose I should have just done that in the first place...) who said of the follow options oar acceptable:

1. 100mm hardcore under 150mm void, with  periscopic vents

2. DPC, with a few stones sprinkled over keep it down, under 150mm void, with  periscopic vents

3. DPC over it, with hardcore up to underside of the spantherm units. ie no void and no periscopic vents needed

 

So I'm currently thinking that 2. is the cheapest option on the basis that periscopic vents will be cheaper than 100mm of hardcore.

 

Does that make sense? Comments on that welcome!

[Oz07]

Don't think 3 is ok but might be misreading it

[sean1933]

On 31/05/2019 at 08:02, nod said:

Normally you would have a hardcore raked out 

Our engineer insisted we put six mtrs of concrete sloping to a drain with an anti flood valve 

I was pretty pissed off at the time 

having to do this 

But I suppose it covers All basis 

 

Pictured is ME You can’t see my face but I think I was sulking 

 

Hi Nod. I'm in a similar situation and our BCO has requested a concrete oversite below B&B with a slight fall to drain. Plan is to lay a DPM then slurry above. I was just wondering, what mix did you use, and how deep? Just trying to decide if I mix on site or order premix - 80m2 to do soon on the garage (house will come later!). I already have the fall created by the soil so was hoping for a 20-30mm cap will suffice.

Thanks

Sean

[nod]

Hi Sean 

I didn’t use a membrane I laid a drain and sloped 5 cube of c3 premix in heavy rain I took me about 5 hours on my own to cover 153m2