Help with Floor insulation

hexosan

Need help deciding on my floor insulation. I need to use 120mm of PIR insulation (Kingspan/quinntherm/ballytherm) the price is working out at roughly €14 per M2. I spoke with the rep from Airpack who claimed 160mm of platinum EPS was the equivalent of the 120mm PIR boards. (Not sure if this is correct) anyone with an opinion of this....
I should mention that the insulation will be placed in a basement floor. The floor is laid on top of an external tanking membrane (Sika proof A-08). From my research PIR insulation doesn't seem to hold up well if introduced to moisture hence why I'm looking at EPS (also cheaper)
I had looked at putting a 50mm screed of hemihydrate on top of the insulation but due to cost I'm now looking at 75mm of concrete 30N10 with reinforcing fibres added to prevent cracking.

fclauson

120 will only just meet regs go for 150 or 200

hexosan

Because I'm below ground it acts as an insulator so there's no need to increase beyond 120mm.

hexosan

Any thoughts on the EPS or how much I'd actually need for it to be the equivalent of the PIR.
The EPS has a thermal conductivity of 0.031

Andrew_Doran

hexosan wrote: »

Any thoughts on the EPS or how much I'd actually need for it to be the equivalent of the PIR.
The EPS has a thermal conductivity of 0.031

mm[PIR] * conductivity[EPS] / conductivity[PIR] = mm[EPS]

So assuming 0.31 for EPS and 0.23 for PIR:

120mm * 0.31 / 0.23 = 161.7mm

Andrew_Doran

Exact performance will of course depend on your floor build up and junctions and so on but basically they are correct with 160mm.

hexosan

Andrew_Doran wrote: »

mm[PIR] * conductivity[EPS] / conductivity[PIR] = mm[EPS]

So assuming 0.31 for EPS and 0.23 for PIR:

120mm * 0.31 / 0.23 = 161.7mm

Thanks for the calculation Andrew.
While I was researching PIR I did come across info which stated that PiR loses its thermal conductivity over time and correct me if I'm wrong is it not closer to .28 long term

Carbonnet

A basement floor is not a 'floor' when calculating u values. The performance of the walls is taken into account when calculating the u value. If none of the companies you ve been talking to has asked you about this you re getting a wrong answer. If there is moisture there, no matter what the insulation type is, heat loss will be thru water, not insulation. Pir thermal vales are quoted as an aged lambda accounting for any losses under en standards.

hexosan

Carbonnet wrote: »

A basement floor is not a 'floor' when calculating u values. The performance of the walls is taken into account when calculating the u value. If none of the companies you ve been talking to has asked you about this you re getting a wrong answer. If there is moisture there, no matter what the insulation type is, heat loss will be thru water, not insulation. Pir thermal vales are quoted as an aged lambda accounting for any losses under en standards.

Wall make up is 250mm RC wall externally tanked, 200mm cavity fully pumped with platinum bead, 100mm internal block wall. First row of blocks will be B5 Quinnlite's.

Site around the basement is fully drained and the cavity will also be drained so hopefully there shouldn't be any moisture issued (fingers crossed)

hexosan

If I was going with 200mm of insulation in the floor is it better to use a 200mm board or (2) 100mm boards laid with the joints crossed & taped.

fclauson

we went 2 x 100 - without tape

whizbang

Has the EPS got sufficient structural strength to use in floor ?

hexosan

whizbang wrote: »

Has the EPS got sufficient structural strength to use in floor ?

It has a compressive strength of <92kPa,

EPS is used in insulated raft foundation systems and they even use it under roads on boggy ground.

In this application the EPS is only supporting the load of the screed on top of it, all the structural elements (the walls) are supported by the raft slab.

Is there a reason you believe if won't ?

Curious Geroge

I'm not at this stage yet but wondered if anyone can take some pictures as it goes down.

I'm interested as how the following is done.

Raft foundation - do I put down some sort of membrane before insulation. Then, how or when do I laid the pipes for drainage and water and what does the floor look like prior to putting on the underfloor piping and the screed. I've not seen it before so any pictures stage by stage, greatly appreciated. Thanks

hexosan

I'm going to lay eps insulation on my raft, do I need to cover the eps with a plastic sheet before the concrete screed is poured or does the concrete not react with eps the same way it does with pir insulation.

Curious Geroge

hexosan wrote: »

I'm going to lay eps insulation on my raft, do I need to cover the eps with a plastic sheet before the concrete screed is poured or does the concrete not react with eps the same way it does with pir insulation.

Hi, looking to use EPS on mine too after reading the diff in cost. Wondered if the plastic sheeting was required ?

Also any suppliers that people may recommend by pm. Thanks

galwaytt

hexosan wrote: »

It has a compressive strength of <92kPa,

EPS is used in insulated raft foundation systems and they even use it under roads on boggy ground.

In this application the EPS is only supporting the load of the screed on top of it, all the structural elements (the walls) are supported by the raft slab.

Is there a reason you believe if won't ?

I know the XPS used by Strabag on the Shannon tunnel is actually 300kPa, so that's what I used, and I've been on a site in UK where they put a raft on XPS and that was 300kPa as well.

BryanF

whizbang wrote: »

Has the EPS got sufficient structural strength to use in floor ?

this is mater for a structural eng to determine on a case by case by case basis. that said EPS has been used for donkeys years under floor screeds and structural slabs. Hexosans eng will determine its suitability in this case.

hexosan

BryanF wrote: »

this is mater for a structural eng to determine on a case by case by case basis. that said EPS has been used for donkeys years under floor screeds and structural slabs. Hexosans eng will determine its suitability in this case.

As Bryan has said it's been used for ages and on numerous projects I'm aware of.

Curious Geroge

galwaytt wrote: »

I know the XPS used by Strabag on the Shannon tunnel is actually 300kPa, so that's what I used, and I've been on a site in UK where they put a raft on XPS and that was 300kPa as well.

Thanks; when you used this in the floor, did you have to cover with plastic and if so, what gauge ? Also, could you PM your supplier and I'll give them a bell. Cheers.

PROJECT K

Depending on manufacturer conductivity for PIR is typically 22mW/m.K (0.022W/m.K) aged value therefore equivalent to 170mm EPS at 31mW - double check the U-Value calcs with the relevant products.

As stated previously water and insulation dont mix, PIR wont readily absorb water but water vapour can be an issue. EPS will take on water but has the ability to evaporate out much easier than PIR - either way moisture content will have a detrimental impact on conductivity so should be avoided (cant imagine you expect water ingress after tanking otherwise you have more serious issues to consider than thermal performance!!!:))

galwaytt

PROJECT K wrote: »

Depending on manufacturer conductivity for PIR is typically 22mW/m.K (0.022W/m.K) aged value therefore equivalent to 170mm EPS at 31mW - double check the U-Value calcs with the relevant products.

As stated previously water and insulation dont mix, PIR wont readily absorb water but water vapour can be an issue. EPS will take on water but has the ability to evaporate out much easier than PIR - either way moisture content will have a detrimental impact on conductivity so should be avoided (cant imagine you expect water ingress after tanking otherwise you have more serious issues to consider than thermal performance!!!:))

EPS will transit water between the beads through capillary action, but not absorb it and the styrene is not affected.

XPS is what I used and does neither.

galwaytt

Curious Geroge wrote: »

Thanks; when you used this in the floor, did you have to cover with plastic and if so, what gauge ? Also, could you PM your supplier and I'll give them a bell. Cheers.

Yes, 600g iirc. The reason is to cut down any leaching of screed down between any gaps in the boards.

Situation

hexosan wrote: »

Thanks for the calculation Andrew.
While I was researching PIR I did come across info which stated that PiR loses its thermal conductivity over time and correct me if I'm wrong is it not closer to .28 long term

Have you got a link for .28 I know it loses its thermal conductivity im just interested in how much it loses.