Vapour barrier

[Pocster]

20 minutes ago, CC45 said:

I also put some of the foam on as well - its cheap & just an insurance policy.  25mm celotex as well.

 

19/12/15 I paid £37.89 for 8x4 x 150mm celotex sheets, I've still got 6 lurking in the garage how much are they now?  Have I made a profit by hoarding??

 

You certainly have !

cheapest inc vat was around £54 

You are in the money ? 

[Oz07]

On 08/04/2019 at 16:47, ADLIan said:

EPS needs DPM under it too.

Really?

[Onoff]

3 minutes ago, Oz07 said:

Really?

 

I wondered. Read some stuff and the water take up of eps is minimal.

[Oz07]

Think must be confused for on top of 

[ADLIan]

Yes eps does need a dpm under it. Check MIs and BBA certs

[Pocster]

2 minutes ago, ADLIan said:

Yes eps does need a dpm under it. Check MIs and BBA certs

Pir isn’t eps though is it ?

[ADLIan]

Same applies to pur/pir. Again check MIs and BBA certs for use in GF

[Onoff]

2 minutes ago, ADLIan said:

Same applies to pur/pir. Again check MIs and BBA certs for use in GF

 

What's GF?

[Pocster]

1 minute ago, Onoff said:

 

What's GF?

Ground floor ?

Mine is “technically “ 1st floor 

[Pocster]

2 minutes ago, Onoff said:

 

What's GF?

Or girl friend ! ?

[Onoff]

Take this passive build for example. 300mm of Peripor polystyrene straight onto the compacted sub base - no membrane underneath:

 

 

[ADLIan]

DPM required in ground floors (GF) with just about all insulation types. DPM not required on upper floors but polythene VCL/slip layer/separating layer needed with insulation under screed

[Pocster]

1 minute ago, ADLIan said:

DPM required in ground floors (GF) with just about all insulation types. DPM not required on upper floors but polythene VCL/slip layer/separating layer needed with insulation under screed

I’m ok then ? . Vcl ordered for non GF 

[Onoff]

4 minutes ago, ADLIan said:

DPM required in ground floors (GF) with just about all insulation types. DPM not required on upper floors but polythene VCL/slip layer/separating layer needed with insulation under screed

 

So I've got compacted Type 2, sand blind, 25mm eps, dpm then 150mm of pir. Are you saying I should have had a dpm under the eps?

[ADLIan]

I assume the eps here is only acting as a ‘cushion’ so probably not

[Pocster]

6 minutes ago, Onoff said:

 

So I've got compacted Type 2, sand blind, 25mm eps, dpm then 150mm of pir. Are you saying I should have had a dpm under the eps?

Better dig it up ?

[Onoff]

9 minutes ago, pocster said:

Better dig it up ?

 

If you can find me a Screweys with one of these in stock I might! ?

 

https://www.screwfix.com/p/z1c-ds-65-14-3kg-hex-shank-breaker-230v/9158v

[Pocster]

1 minute ago, Onoff said:

 

If you can find me a Screweys with one of these in stock I might! ?

 

https://www.screwfix.com/p/z1c-ds-65-14-3kg-hex-shank-breaker-230v/9158v

A breaker for 40 quid !!! It would break !

Got my Hilti for that !

[Cpd]

I can definitely say that PUR / calotex does eventually become waterlogged..... i get a lot of seconds given to me for nothing and some gets stored outside until I can find space inside...... recently I really needed a few sheets of 60mm and the only ones I had were at the bottom of a pile stored outside, they had been there for a few years...... the bottom one was like a sponge and even when I cut into its middle it was still wet. It’s the first time I have never seen this as normally water is only present in the first few mm with sheets that have been stored outside for short / medium periods of time. Just goes to show how important it is to use the right stuff and the proper systems for the materials being used. 

[Onoff]

3 minutes ago, Cpd said:

I can definitely say that PUR / calotex does eventually become waterlogged..... i get a lot of seconds given to me for nothing and some gets stored outside until I can find space inside...... recently I really needed a few sheets of 60mm and the only ones I had were at the bottom of a pile stored outside, they had been there for a few years...... the bottom one was like a sponge and even when I cut into its middle it was still wet. It’s the first time I have never seen this as normally water is only present in the first few mm with sheets that have been stored outside for short / medium periods of time. Just goes to show how important it is to use the right stuff and the proper systems for the materials being used. 

 

Fully agree about pir taking up moisture. But eps...the stuff they make swimming floats from???

[Oz07]

Maybe certificates are relevant to some minute level of performance. Refuse to believe that all these passive slabs have been installed wrong but would be a bit of a laugh I suppose. @JSHarris @PeterStarck digging yours up anytime soon

[Jeremy Harris]

EPS has a long track record of being used in wet ground without any problems.  Before being used for passive slab insulation it was used for lots of basement builds in Germany and Austria, for around 50 years now, with no problems from moisture ingress.  I believe they've even used EPS raft foundations to build railway lines across deep bogs, too.

[Moira Niedzwiecka]

I have suspended beam & block grouted with sand & cement.

1200 dpm lapped up the walls & sealed to the DPM with bitumen tape.

I also put butyl grommits over drainage pipes etc coming through the floor & taped them around the edges & the upstands to the pipe

75mm celotex with joints taped. I used duct tape from Lidl.

150mm celotex laid opposite way so joints staggered & then taped.

100mm perimeter celotex

500 gauge dpm

foam perimeter expansion strip

50mm calcium sulphate screed.

Good idea to take photos & measurements of where UFH pipes run in relation to walls & windows etc.

.

[Onoff]

@pocster, are you having a pumped liquid screed at "only" 60mm?

[ADLIan]

The comparison of EPS floor insulation to swimming floats is irrelevant - as a floor insulation it has a critical technical function to fulfill over the lifetime of the building.

In constant contact with moisture, say under a DPM, EPS can absorb water something like 3-5% by volume (there are some newer products with enhanced water resistance where this figure may be 2% or better - these are often coloured pink, green, blue etc to make them look like extruded poly).

This moisture absorption can add between 2-4 mW/mK to the thermal conductivity of EPS. Other physical properties generally not affected hence their use as inert fill/void formers.