Anybody have 75mm depth polished concrete floor above ufh?

[KillyfadNewBuild]

Hi,

 

I was hoping to get feedback from members who have polished concrete flooring at 75mm (or close to depth) above underfloor heating.

 

I want to maximise my sub floor insulation thus dropping from 100mm recommended by my contractor to 75mm (I have another post getting insulation advice and was hoping here to gain advice from members who maybe have a 75mm slab or close too)

 

I am getting ready for the conversation tomorrow morning with the potential concrete provider and our contractor and was hoping to get advice from others who have polished a 75mm slab on the their experience regarding pros and cons.

 

Many thanks,

 

Joe

 

 

[jack]

What's your 75mm concrete going on top of? If it's to be the sole structural slab, that sounds thin for concrete. 

 

I have a ~65-70mm polished concrete layer on top of a nominally 100mm slab (with many deeper ribs and a couple of spines along structural walls) with 300 EPS insulation underneath. The slab has the UFH pipework.

 

We were told 75mm minimum, but didn't have the height available, so we were required to sign something saying we understood the risks. We do have cracks in a couple of places.

 

 

[KillyfadNewBuild]

Taken from the plans (Already in place);

'150mm insitu concrete on 1200 gauge ‘Visqueen’ D.P.M. on 50mm blinding on 150mm min hardcore

Hardcore compacted in max 215mm layers'.

 

We then hope to have 150mm of Kingspan board insulation below the UFH then 75mm concrete slab on top to be polished.

 

 

[KillyfadNewBuild]

9 hours ago, jack said:

What's your 75mm concrete going on top of? If it's to be the sole structural slab, that sounds thin for concrete. 

 

I have a ~65-70mm polished concrete layer on top of a nominally 100mm slab (with many deeper ribs and a couple of spines along structural walls) with 300 EPS insulation underneath. The slab has the UFH pipework.

 

We were told 75mm minimum, but didn't have the height available, so we were required to sign something saying we understood the risks. We do have cracks in a couple of places.

 

 

 

Thanks for your reply, Jack. 

 

We were meant to have more depth to work with but that wasn't the case in the end so it's now a trade off.  If I want my 150mm of Kingspan insulation, I need to drop the concrete slab over the ufh to be polished to 75mm which my contractor had already recommended against but if the supplier/polisher says 75mm is fine to work with, ultimately the decision is down to us.

[KillyfadNewBuild]

Just to confirm the concrete provider and polisher said the minimum they would do is 75mm

 

He would always recommend 100mm as 75mm would be more prone to cracking but he said it's doable and just a little more prep work would need to be done.

 

Hopefully this can help others down the line in similar position.