Breathable Membrane: Renovating & Retrofitting Brick Veneer

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Breathable Membrane: Renovating & Retrofitting Brick Veneer

(16 posts) (6 voices)

Started 4 years ago by BAP
Latest reply from Francis

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BAP
Member

I am in the process of stripping the gyprock from a house with the view to insulate inside timber framework with brick veneer exterior. I am keen to install a breathable membrane (sarking?) before installing the insulation and would like to make the building as weather tight as possible.

If it was a new building the membrane would be put on the exterior of the timber framework prior to brickwork.

I haven't found any recommendations from membrane manufacturers for retrofit of a renovation. Any suggestions on how best to install?

One idea I have is to cut the breathable membrane into smaller sheets, staple inside stud work and push insulation in for a tight fit but maintain air gap with exterior brick wall.

Another idea is to put the insulation on as a continuous layer on the inside over the top of insulation before re-sheeting with plasterboard.

Or, both.

Has anyone done this before or have recommendations?

Many thanks,

Brad

Posted Friday 22 Sep 2017 @ 3:06:44 pm from IP #
Annette
Member

There have been posts about this on the forum previously - so a search will bring up more responses.

I have retrofitted insulation, by removing the internal plasterboard and stapling sarking inside the stud 'pockets'. I also used string looped behind the studs to prevent the sarking pushing out and touching the bricks.

I used breathable reflective foil laminate (RFL) when I did the first section of the house.

However, when I do the remainder, I will likely use something with even more breathability like Proctorwrap or similar.

I used Bradford Soundscreen R2.5 wall batts which are perfect for 90mm studs in rooms I wanted some sound protection. In rooms where I wasn't so worried about sound, I used Earthwool R2.5 wall batts which are a bit cheaper.

If you end up putting sarking on the internal face of the studs, (directly under the plasterboard) you have to consider how you will glue the plasterboard to the studs as the glue has to be on the wood, not on sarking.

Posted Friday 22 Sep 2017 @ 11:48:21 pm from IP #
BAP
Member

Thanks Annette,

Very helpful. Confirms much of what I was thinking so great to have someone who has done this before.

Posted Saturday 23 Sep 2017 @ 10:43:01 am from IP #
AndyG
Member

Annette said:
If you end up putting sarking on the internal face of the studs, (directly under the plasterboard) you have to consider how you will glue the plasterboard to the studs as the glue has to be on the wood, not on sarking.

I would install a counter batten on top of the membrane between the membrane and the gyrock giving you another air gap and even better thermal properties.

Posted Saturday 23 Sep 2017 @ 9:41:45 pm from IP #
dave lawrence
Member

agree with both posts above . counter battens a good idea. one further thing to add... you don't have to glue the plasterboard ... you could also screw fix it.

Posted Sunday 24 Sep 2017 @ 5:11:53 am from IP #
Johnnojack
Member

Sounds to me like putting foil on the brick side would be best as there is a ready made air gap so the foil can do its job of reflecting. On the plasterboard side you have insulation on one side hard against it and plasterboard on the other, no air gaps at all, doesn't that make it next to useless? Putting battens on the inside is a bit of a job and brings complications of no longer fitting around Windows etc.

Posted Sunday 24 Sep 2017 @ 7:04:29 am from IP #
AndyG
Member

Its not hard to get wider window reveals fitted from the factory if you're updating your windows, or adding wider reveals yourself if using the existing windows.
Certainly easier than trying to get foil on the outside of the frame. As suggested earlier though, if thats your plan of attack, than carefully attaching between studs is the way to go (only way really!)

Posted Sunday 24 Sep 2017 @ 8:37:51 am from IP #
BAP
Member

Thank you. All very good ideas.

I am thinking I might line the studs with breathable membrane and push the insulation in. Glue the central area of the plasterboard and screw along the edges as normal. For other areas e.g., corners or top plate where it might not be possible to put in breathable membrane behind the insulation I am thinking of putting a strip of breathable membrane on the plasterboard side so it overlaps the nearby insulation and breathable membrane that sits behind.

Posted Sunday 24 Sep 2017 @ 9:45:34 am from IP #
dave lawrence
Member

very difficult to install membrane correctly on the inside (cavity side ) of the studwork.
Hence the idea of counterbattens installed on the outside face of the studwork . more woerk but far more effective ..but you end up losing 20 -35mm from the width of each external wall.(depending on the thickness of the battens you use )

Posted Monday 25 Sep 2017 @ 12:44:06 am from IP #
Johnnojack
Member

There was some time ago an article/thread about some one who removed just a section of gyprock across the middle of his walls, from memory it was about 300 or 400mm top and bottom of the noggin. He then slid batts in to the top plate and to the bottom. Replaced gyprock and reflushed wall. May be easier but won't get foil in.

Posted Monday 25 Sep 2017 @ 2:36:04 am from IP #
Francis
Member

Alan Pears: http://www.ata.org.au/wp-content/uploads/renew_98_99_wall_insulation_retrofit.pdf

Posted Monday 25 Sep 2017 @ 4:48:18 am from IP #
Annette
Member

Francis said:
Alan Pears: http://www.ata.org.au/wp-content/uploads/renew_98_99_wall_insulation_retrofit.pdf

Interesting article. However, the author chose not to use paper tape on the joints - or any tape. The joints are bound to crack as a result.

Posted Monday 25 Sep 2017 @ 8:40:14 am from IP #
Francis
Member

You're probably right but I think it was more a demonstration of how to retrofit insulation than how to plaster. He is a regular contributor to renew and an RMIT lecturer: https://en.m.wikipedia.org/wiki/Alan_Pears

Posted Monday 25 Sep 2017 @ 10:06:49 am from IP #
Johnnojack
Member

Good work Francis.

Posted Monday 25 Sep 2017 @ 11:42:22 am from IP #
BAP
Member

Thank you all. I'd read Alan's article previously but couldn't locate it. I already have the plasterboard stripped throughout the house so I could check all the timber (oregon) frame as there had been termite activity in the past but no evidence at the moment. I thought before I insulate and plasterboard I'd but a breathable membrane in behind.

Everyone's post has been very helpful.

Posted Monday 25 Sep 2017 @ 3:11:12 pm from IP #
Francis
Member

I think before putting any kind of wrap you should read the guide on http://yourhome.gov.au/passive-design/sealing-your-home on "Avoiding condensation from air sealing". Placement of vapour barriers and permeable membranes need to take into account your climate, ie whether it is more humid outside or in and whether it is heating or cooling dominated.

Posted Monday 25 Sep 2017 @ 10:14:08 pm from IP #

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