Single brick garage wall advice

[RMS]

Hi all

In the process of installing studwork to my single brick garage wall. The studwork is sat away from the brick wall and I will be fitting celotex insulation boards within the studs then plasterboard with a moisture barrier.

Am I right in thinking I need to fit a membrane on the back side of the studwork? If so will standard roofing membrane do?

When installing this I would plan to nail it to the back of the studwork horizontally starting from the bottom and lap the joints. I would also ensure the bottom piece is placed behind the floor dpm. Does this sound right? Do I need to tape the joints?

All help is appreciated.

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• RMS
• 28 Jul 2014
• 1

 

[LanceCorpralJones]

I was of the opinion that the VPM should always be on the warm side.
Perhaps this link helps:
http://www.energybooks.com/pdf/D1142.pdf
A VPM can be a lightweight palstic sheet and does not need to be anywhere near as substantial as roofing membrane. Once the PB is installed it will be protected from potential damage.

 

[RMS]

From what I've read... A vapour barrier is required on the warm side to stop the passage of moisture from inside the room.

A breathable permeable membrane is required on the back side of the studwork to stop ingress of water from the brickwork and allow moisture to escape from within the studwork.

A lot of websites show this method. Was wondering the membrane used for roofing is the same product?

 

[Grenage]

If you have a gap between the stud/board and the brick wall, I'm not sure you'd even need a breathable membrane - others will no doubt correct me if not the case.

When I insulated a single-brick cupboard, I used breathable roofing membrane; I attached it to the wall using DPM jointing tape, because I happened to have some knocking around. Due to space constraints, I did not leave a gap between the wall (the wall was always dry).

So it was:

Wall
Breathable membrane
Stud/celotex
Insulated board (for thermal bridging reduction)
Vapour barrier
Plasterboard.

Much as you already suggested; I probably didn't need the vapour barrier as the thermal board was foil-backed, but I had some of that knocking around, too.

 

[RMS]

Thanks for the responses

I decided to use Tyvek house wrap for the membrane

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• RMS
• 3 Aug 2014
• 1

Just ready for the insulation to be added. Do you think I need to seal/tape the joint between the house wrap and the dpm?

The only problem I have is what to do with this part of the wall. There was a wall removed (non load bearing) and this small part was left as it strengthens the pillar at the front of the garage. This will be built up to ceiling level. I want this to be plastered but there is no no cavity between this and the external pillar. Wondering if insulated plasterboard would be acceptable or could there be a problem with damp?

Any suggestions are appreciated?

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• RMS
• 3 Aug 2014
• 1

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• RMS
• 3 Aug 2014
• 1

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• RMS
• 3 Aug 2014
• 1

 

[Grenage]

Hi RMS,

I don't think you'd need to tape the joint, especially as the DPM comes up a fair way.

As for covering that small section, I don't know; I suppose in your position I'd be tempted to affix some leftover membrane and board over. It really depends on how much water the wall takes in during wet and windy weather.

Hopefully this bump will get you some advice from someone with more experience.

 

[freddiemercurystwin]

Can't be arsed to read the whole thread but WTF is there a membrane on the back of the studwork for? For a garage conversion you can slap some blackjack on the back of the existing wall, that stops any moisture getting through, foil backed plasterboard is the only membrane required in the whole wall make-up. Are BC involved in this? Jeez louise!

 

[RMS]

Can't be a***d to read the whole thread

Then don't reply to it peeper!

but WTF is there a membrane on the back of the studwork for?

It's a breathable membrane to allow the moisture out of the stud work.

For a garage conversion you can slap some blackjack on the back of the existing wall, that stops any moisture getting through, foil backed plasterboard is the only membrane required in the whole wall make-up.

I'm sure you can. However, it's clear there's more than one way to do this. I am aware a vapour barrier I required on the warm side.

Are BC involved in this? Jeez louise!

No

 

[freddiemercurystwin]

Whatever. Goodluck with you're 'build'.

 

[RMS]

Whatever. Goodluck with you're 'build'.

Okay, thanks for what little help you've been.

 

[Grenage]

As far as I'm aware, the breathable membrane is preferable to a painted DPM, as it allows water vapour out.