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LA3222

VCL & SIP

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Just been doing a bit of reading and the answer seems inconclusive.  Some say a seperate VCL is still required with SIPs whilst others suggest that as long as the seams are taped then the SIP structure itself will perform as a VCL.

 

I'm interested in hearing what members who used SIPs did in this regard.

 

TIA

 

Jamie

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we definitely needed vcl, though I just boarded it out with foil backed plasterboard instead

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I made sure all panels were glued all the way round, I then siliconed all joins before adding the VCL. MVHR will also help.

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So you did use a VCL then @oranjeboom The company I'm considering replied yesterday to say that provided it's erected correctly and a ventilation system is used, a VCL is not required.

 

I don't like the idea of not using one.  I intend to add an internal layer of Kingspan insulation which if the joins are taped acts as a VCL.  I'm considering using this approach to create a VCL - not sure if this is the best way to skin this particular cat yet though.

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Yes, I did VCL it. With regards to " it's erected correctly" comment, I would always assume that it won't be. Most installers want a quick erection (ahem) and not all panels will be sealed. Even if they guarantee their work, it will be difficult to prove the installers were at fault years down the track. I would emphasize that you are after a Passivhaus level of build (if they even know what PH is). They may take a bit more notice. But I would definitely add a VCL.

 

As for the PIR - how much are you going to add? If you add to much, there could be issues with condensation on the SIP structure. IIRC, it's best to add any insulation on the outside of the SIPs, but see what the SIP company say (or simply go for deeper SIP panels). Don't forget that you'll need a service void also for cables and pipes so adding celotex on the inside will need battening perhaps still.

 

Adding a VCL is a straight forward job if you are doing this yourself (I would not trust anyone else to do it properly). Staple gun, spray glue and plenty of tape is all you need. And this of course: https://www.screwfix.com/p/capital-valley-plastics-ltd-vapour-barrier-green-300ga-2-5-x-20m/12869

 

As an aside note, have you considered insulating your soleplate? There's mention on that on this forum also as well as GBF.

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Right...this time is upon me. What's best practice for installing this? Spray glue onto the SIP panel then seal the joins around windows and lapped joints? I'll need a separate thread likely but thought I'd start here. @LA3222 I know you got a great result, I'm not planning added internal insulation but defo tape and VCL. Was thinking of taping all SIP panel joins then doing VCL but I can imagine this would be fortunes in tape? 

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@SuperJohnG don't over think it bud, it's easy. I used Intello products. I used the intello plus membrane with the tescon vana tape. They do a double sided tape too. I ran strips of that along the wall near top, middle, bottom so it would hold the membrane temporarily. Then used the tescon to seal it to ceiling, floor, windows etc. By time you've done that it effectively takes the weight. I would then batten the wall so it pins the membrane in place. 

 

A couple of times on sloped Ceiling and one wall I didn't batten straight away and the membrane sagged which was a bit of a pain to re-tension.

 

I used orcan f in joins such as membrane to concrete slab, not really for that but I used it that way.

 

Around joists, studs etc its a pain. Just a case of suck it up and use lots of tape. Don't underestimate how much tape you will use, I think your build is a similar size to me and I think I used over two full boxes (think its 20 to a box iirc). Try and source it all from Germany, it's far cheaper, they stopped exporting to UK just after Brexit, not sure if they have resumed? If they haven't I would almost say it's worth a trip to Germany as I think there's a couple of thousand in savings to be made potentially.

  • Thanks 1

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On 31/08/2021 at 08:39, LA3222 said:

@SuperJohnG don't over think it bud, it's easy. I used Intello products. I used the intello plus membrane with the tescon vana tape. They do a double sided tape too. I ran strips of that along the wall near top, middle, bottom so it would hold the membrane temporarily. Then used the tescon to seal it to ceiling, floor, windows etc. By time you've done that it effectively takes the weight. I would then batten the wall so it pins the membrane in place. 

 

A couple of times on sloped Ceiling and one wall I didn't batten straight away and the membrane sagged which was a bit of a pain to re-tension.

 

I used orcan f in joins such as membrane to concrete slab, not really for that but I used it that way.

 

Around joists, studs etc its a pain. Just a case of suck it up and use lots of tape. Don't underestimate how much tape you will use, I think your build is a similar size to me and I think I used over two full boxes (think its 20 to a box iirc). Try and source it all from Germany, it's far cheaper, they stopped exporting to UK just after Brexit, not sure if they have resumed? If they haven't I would almost say it's worth a trip to Germany as I think there's a couple of thousand in savings to be made potentially.

Thanks for this only just noticed you'd replied.

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