Johnny Jekyll

I'm using Cavity Therm full fill (including pre-formed corners) in the walls and currently Xtratherm T&G in the floor. So it's all tongue and groove. They say it's a continuous system that delivers a superior thermal bridging detail. And no need for taping. I have it on site and to be fair it really does fit together very snug.

Hi guys, Can I get your opinions on this set-up with insulation in place and DPM and DPC locations? All good, or any glaring errors. Thanks very much.

Great info thanks very much Peter. This forum is absolutely superb. As I improve I hope to contribute where I can.

Interesting take on things Russell. I'll definitely enquire with the manufacturer. But as I already have the PIR on site it may be easier to just add the 200mm EPS to the set-up. Still the questions below if anyone has opinions thanks: 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?

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

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.

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

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.

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

Thanks very much Faz.

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 joists are already here so another order would cost £1500+ I'll ask the bricky and see what they say. Thanks.

Again great info thanks.

Yes 215mm / 225mm with the mortar joint. No can't really have a run of bricks.

Yes please photos and a website link if possible to where I can see them would be great. Thanks.

The joists were at 253mm so that the mid floor area would have enough room for both steels and MVHR ducts to run past each other. Very annoying I know.

Thanks, unfortunately the posi joists are already on site so gotta find a way around it. Notching the blocks looks like it will have to be.

We're using 253mm high posi-joists (Mitek system already purchased) for our two storey detached house. The reason for using posi-joists is MVHR. The posi-joists will sit on top of the 100mm blockwork inner skin at the required height (we are not using joist hangers). We are planning to use the tony tray technique for airtightness around the joists. The problem is the joists are 253mm high (compared to blocks which are 225mm high with the mortar joint), so am I correct in thinking we will need to notch out a bit of the block above around the top of each joist (to enable the blocks to continue up in sync with the external skin) and carefully lap the membrane around the notch as we go? Thanks

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?

Thanks

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.

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

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

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