Vapour barrier

[Pocster]

Hey !

 

So UFH installer has taken a look .

He wants 150mm pir on floor then vapour barrier before they put ufh pipes followed by screed .

What type of vapour barrier should I use ? . I assume I tape any joints ( with what ? ) . I assume I run it up the timber frame studs so screed doesn’t touch studs and also to stop screed going under ufh .

Any advice welcome! ?

[PeterW]

Ordinary DPM will do

[Pocster]

8 minutes ago, PeterW said:

Ordinary DPM will do

Oh ?

So nothing special ? Any old DPM ? - what do I tape it with ?

[PeterW]

Overlap it and tape it with duct tape or 100mm pvc tape. 1200g DPM will be fine.  It’s only to stop the screed running under the insulation. 

 

Its an easy job to do yourself - also check Seconds & Co for PIR. Has he specified an upstand too ..?

[Pocster]

8 minutes ago, PeterW said:

Overlap it and tape it with duct tape or 100mm pvc tape. 1200g DPM will be fine.  It’s only to stop the screed running under the insulation. 

 

Its an easy job to do yourself - also check Seconds & Co for PIR. Has he specified an upstand too ..?

He said an upstand . Didn’t spec it ; but when I said 25mm pir he didn’t quibble 

[Onoff]

You want a perimeter expansion strip too I think?

 

 

 

I used Polypipe panels instead of an actual sheet of DPM to both isolate the foil from the screed (wet concrete in my case) and to clip the pipes to.

 

.

[Pocster]

3 minutes ago, Onoff said:

You want a perimeter expansion strip too I think?

 

 

 

I used Polypipe panels instead of an actual sheet of DPM to both isolate the foil from the screed (wet concrete in my case) and to clip the pipes to.

 

.

I thought the pir upstand did that aswell ?

[Onoff]

1 minute ago, pocster said:

I thought the pir upstand did that aswell ?

 

Sorry, didn't realise you were having one. Think you're right. 

[nod]

3 hours ago, pocster said:

Hey !

 

So UFH installer has taken a look .

He wants 150mm pir on floor then vapour barrier before they put ufh pipes followed by screed .

What type of vapour barrier should I use ? . I assume I tape any joints ( with what ? ) . I assume I run it up the timber frame studs so screed doesn’t touch studs and also to stop screed going under ufh .

Any advice welcome! ?

I put a 1 mtr membrane around the perimeter and taped it to the dmp 

Then ran then ran another layer up against the walls 

and and another layer on top of the 250 insulation 

Few pics may help you 

[Onoff]

30 minutes ago, nod said:

I put a 1 mtr membrane around the perimeter and taped it to the dmp 

 

I too did similar taking blue DPM a metre up the two external walls as my picture above. This sits behind the (again blue) DPM that's under the PIR. The window wall was damp as the outside path was above the dpc and the original bathroom floor was on or at the dpc of the internal leaf. I figured any damp getting behind the wall DPM would go straight down and stay under/behind the DPM under the pir. 

[nod]

9 hours ago, Onoff said:

 

I too did similar taking blue DPM a metre up the two external walls as my picture above. This sits behind the (again blue) DPM that's under the PIR. The window wall was damp as the outside path was above the dpc and the original bathroom floor was on or at the dpc of the internal leaf. I figured any damp getting behind the wall DPM would go straight down and stay under/behind the DPM under the pir. 

Yep only one chance to do it  Worth being over cautious

I helped my wife with the sheets of insulation and she did the rest 

[Pocster]

On 04/04/2019 at 23:37, Onoff said:

 

I too did similar taking blue DPM a metre up the two external walls as my picture above. This sits behind the (again blue) DPM that's under the PIR. The window wall was damp as the outside path was above the dpc and the original bathroom floor was on or at the dpc of the internal leaf. I figured any damp getting behind the wall DPM would go straight down and stay under/behind the DPM under the pir. 

Why dpm under pir ?

i was just going to do pir , pir upstands and dpm over that 

[Pocster]

A question !

As I had to raise my outside ‘floor’ by 50mm so my internal floor will raise .

Currently doorway openings are lower . Do I need to raise them ? I.e can I let the screed ‘run’ from one room to the other - or should each room be screeded individually - so screed doesn’t run across doorway 

[Onoff]

25 minutes ago, pocster said:

Why dpm under pir ?

i was just going to do pir , pir upstands and dpm over that 

 

PIR no good if any chance of damp.

 

EPS is the kiddie for damp, that's why all the passive brigade put "300mm of eps" under their slabs.

 

 

[Pocster]

14 minutes ago, Onoff said:

 

PIR no good if any chance of damp.

 

EPS is the kiddie for damp, that's why all the passive brigade put "300mm of eps" under their slabs.

 

 

Ok. I'm on beam and block ( upper floor!)

 

So!

 

DPM around room taped up the sides.

PIR on that taped + PIR up stands 

DPM over that taped up the sides

 

yeah?

 

What about the holes for return and flow fo UFH?. Mine are coming up through the block floor. I don't think expanding foam likes plastic pipework. So what do I fill that with?; also assume just tape around the holes to DPM

[ADLIan]

EPS needs DPM under it too.

[Mr Punter]

25 minutes ago, pocster said:

A question !

 As I had to raise my outside ‘floor’ by 50mm so my internal floor will raise .

Currently doorway openings are lower . Do I need to raise them ? I.e can I let the screed ‘run’ from one room to the other - or should each room be screeded individually - so screed doesn’t run across doorway 

 

Best to stop the screed at doorways as it will perhaps crack. Leave a 10mm expansion gap exactly halfway under where the door will be.  Do the same for tiles if you are having them.

[ADLIan]

No dpm required for upper floor but you will need membrane above the  pur - acts as slip layer and vcl

[Pocster]

4 minutes ago, Mr Punter said:

 

Best to stop the screed at doorways as it will perhaps crack. Leave a 10mm expansion gap exactly halfway under where the door will be.  Do the same for tiles if you are having them.

We will be having tiles .

My doorways are part on the blockwork that the timber frame sits on . So not entirely sure what you mean . Will take a photo tomorrow 

[Pocster]

1 minute ago, ADLIan said:

No dpm required for upper floor but you will need membrane above the  pur - acts as slip layer and vcl

Ok - this is where I’m getting confused 

 

is dpm , membrane , vcl the same thing by different names in this context  ??

[Pocster]

UFH company says for upstairs

 

"We recommend a heavy duty 500G (polythene gauge) / 125m u (micron thickness) polythene membrane for the vapour barrier, green/clear so that you can see any markings made below."

 

I'm guessing by "marking below" he means any markings I place on the PIR to show (for example) where I don't want pipework.

Edited April 8, 2019 by pocster

[Pocster]

Floor to top of timber frame is 23cm 

My floor has to be 50mm higher than planned .

So I assume 150mm pir allows plenty ( 60mm ish ) for ufh and screed .

Edited April 9, 2019 by pocster

[Pocster]

Step in block work at front wall - can’t remember why .

Pack out with pir ; then our upstand in place . Just demo at the moment until someone says it’s wrong . If ok will foam in 

[Pocster]

So in essence this ! ( with upstand at far end of course ) 

[Pocster]

Hmmmmmm

looking back at other photos i’m Not so sure now ! .

Should the upstand be the same height as the floor pir ? I.e in my case 150mm - so it’s all flush ??