The make-up of our floor (not including DPMs etc) is:

 

75mm screed

150mm PIR floor insulation (high quality tongue and groove)

375mm RC35 Reinforced raft foundation - already laid

100mm ST4 blinding layer - already laid

 

To cut a long story short, we may have to raise the internal floor height (and the DPC) by 150mm.

 

The DPC would be easy enough, either extra courses of engineering bricks or a trench block.

 

Regards the insulation, we could of course lay another 150mm PIR floor insulation, making it 300mm overall. But the floor is easily good enough as is for SAP Calcs and another 150mm of PIR floor insulation would cost £1,500+. Is there a cheaper alternative to raise the internal floor height considering it's non structural?

 

Thanks

Use 300mm EPS instead of the PIR (or have you bought that already?)

Just now, ProDave said:

Use 300mm EPS instead of the PIR (or have you bought that already?)

 

Yes have purchased the 150mm PIR floor insulation already. So need to work around that?

Could we lay 150mm EPS below the PIR? Sorry never looked at EPS?

1 minute ago, Johnny Jekyll said:

Could we lay 150mm EPS below the PIR? Sorry never looked at EPS?

Yes, even better from a u-value. Just make sure it's floor EPS which can take the load. Don't go buying roof EPS.

Just now, Dudda said:

Yes, even better from a u-value. Just make sure it's floor EPS which can take the load. Don't go buying roof EPS.

 

Thanks, sorry would it be possible top provide a link to the correct product. I'm very happy to search, just want to make sure it's the correct one.

Just now, Johnny Jekyll said:

Thanks, sorry would it be possible top provide a link to the correct product. I'm very happy to search, just want to make sure it's the correct one.

I'm based in Ireland and the suppliers in the UK are different. Just search 'EPS floor insulation'. This is the first that came up for me with a .co.uk address

https://www.insulationsuperstore.co.uk/browse/insulation/insulation-board/floor-insulation/stylite-eps.html

1 minute ago, Dudda said:

I'm based in Ireland and the suppliers in the UK are different. Just search 'EPS floor insulation'. This is the first that came up for me with a .co.uk address

https://www.insulationsuperstore.co.uk/browse/insulation/insulation-board/floor-insulation/stylite-eps.html

Thanks

Thanks guys. So this would do the job perfect and much cheaper than the PIR

https://www.insulationsuperstore.co.uk/product/jabfloor-100-polystyrene-insulation-24m-x-12m-x-150mm-1152m2-pack.html 

 

May I just check, do you think it's ok to put a 150mm EPS layer and a 150mm PIR layer together? I'm just thinking out the box, they can't react with each other can they?

And which would be best on top? The PIR I already have is very good stuff so think that may be best on top? 

Yes it's fine. EPS at the bottom.

15 minutes ago, Dudda said:

Yes it's fine. EPS at the bottom.

Thanks

6 hours ago, Johnny Jekyll said:

Thanks guys. So this would do the job perfect and much cheaper than the PIR

https://www.insulationsuperstore.co.uk/product/jabfloor-100-polystyrene-insulation-24m-x-12m-x-150mm-1152m2-pack.html 

 

May I just check, do you think it's ok to put a 150mm EPS layer and a 150mm PIR layer together? I'm just thinking out the box, they can't react with each other can they?

And which would be best on top? The PIR I already have is very good stuff so think that may be best on top? 

 

You can get 150mm PIR cheaper than that

4 hours ago, wozza said:

 

You can get 150mm PIR cheaper than that

I thought £30 per board including VAT was pretty good. But if you know where I can cheaper then that would be great? Thanks.  

We are now looking at further raising the finished floor height / DPC to 6 courses of bricks off of our reinforced raft slab.

So that's 6 x 75mm (brick 65mm and 10mm mortar) = 450mm.

 

We have 75mm screed at the top.

We already have the 150mm PIR insulation on site below the screed.

So we need to add 225mm below the PIR?

 

Is it ok to add 225mm EPS floor insulation under the PIR? I guess what I'm asking is there a maximum amount of insulation you can lay under a 75mm screed?

 

Thanks

Make the screed 100mm and the EPS will be fine. Beware though at 450mm some BCOs may ask for a beam and block or suspended floor. 

9 minutes ago, PeterW said:

Make the screed 100mm and the EPS will be fine. Beware though at 450mm some BCOs may ask for a beam and block or suspended floor. 

 

So is it a no no for 225mm EPS and then 150mm PIR and then 75mm screed?

Would like to keep 75mm max screed otherwise the wife will moan when the slab takes too long to warm up in the winter : o }

Just thinking, maybe 75mm MOT and sand below 150mm EPS.

Just need to bring the floor height up.

39 minutes ago, Johnny Jekyll said:

 

So is it a no no for 225mm EPS and then 150mm PIR and then 75mm screed?

Would like to keep 75mm max screed otherwise the wife will moan when the slab takes too long to warm up in the winter : o }

Just thinking, maybe 75mm MOT and sand below 150mm EPS.

Just need to bring the floor height up.

Sorry actually thinking Peter, are you saying 100mm screed because it will be more sturdy on top of all the insulation?

 

Why are you jacking up the FFL so much after the beams are in out of interest?

6 minutes ago, Faz said:

Why are you jacking up the FFL so much after the beams are in out of interest?

 

It's a 375mm reinforced raft slab (no beams). Has gone in well but unfortunately 225mm too low in the ground (long story).

So need to bring up the DPC and finished floor level a little.

Two blocks instead of one for the DPC is easy enough.

Just need to bring the internal floor up as well. Hence 225mm EPS below the PIR or another solution.

Frustrating but needs to be done.

  

Ok - I would make it up with the poly then - a mistake to introduce type 1 and sand I would have thought and it probably wouldn't save much although I had an email from Floorspan this week saying that all of their EPS prices were rising due to a world shortage.

 

Are you able to pass the costs on?

On 30/03/2021 at 22:22, Johnny Jekyll said:

I thought £30 per board including VAT was pretty good. But if you know where I can cheaper then that would be great? Thanks.  

 

The link you included was for 2 boards at £119.60 so PIR would be cheaper at that price.

 

Have you considered using PIR seconds?

EPS will be fine and the difference in warm up will be negligible. 75mm is a thin screed at the best of times. 

75mm is too thin for that amount of insualtion. Up it to 100mm. You should be able to get EPS boards for £20 or less. Ring round local merchants and ask for best price for the quantity you need. Some merchants don't bother much with EPS so you'll never get a good price. Trick is finding one that sells in high volume and trades regularly.

Edited April 1, 20215 yr by Conor

All interesting thanks guys.

Wozza, the Jabfloor was for a 11.52m2 Pack (4 boards). I had to check it twice because I also thought it was expensive. It's for 4 boards so better value. 

 

So shall I change it to this:

100mm screed - question... can I use a self levelling liquid screed at this thickness?

150 PIR insulation (already on site)

200 mm EPS insulation

 

Do you think the BCO will have a problem with this? If so why?

 

Thanks

Edited April 1, 20215 yr by Johnny Jekyll

So I would look at this differently and do the lot in EPS buy it in bulk and save a fortune on PIR prices. 

Sell the pir or use it in the roof. 

 

Go to an eps manufacturer dont  buy it from a re seller, they will cut it to any thickness you want so you can tweak your finished floor height. 

 

 

Edited April 1, 20215 yr by Russell griffiths