Interior insulation behind the shower wall

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chez

93 posts

Master Geek

#302920 4-Jan-2023 10:37

Bathroom wall is currently stripped off. There is no insulation behind the shower wall and there was a bit of a noise heard when someone was using the shower. It's an interior wall where a bedroom is next to the bathroom. Downstairs shower wall has no insulation as well but I'm not bothered because it's a toilet room next to it. I'm thinking of putting a regular Pink Batts Silencer wall insulation or Bradford Gold R2.2. Can I put an internal wall insulation behind the shower wall without creating a problem in the future? I can't find a building code about this. I can't find any resource in NZ search. All I see is overseas references.

beddy

93 posts

Master Geek

#3017028 4-Jan-2023 20:16

The guy who remodeled my ensuite suggested I do the same, so I assume it should be OK.

billgates

4705 posts

Uber Geek

Trusted

#3017044 4-Jan-2023 21:06

We insulated all our internal walls including shower walls and there was no issues with any code couple of years ago.

Do whatever you want to do man.

Stu1

1734 posts

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#3017179 5-Jan-2023 08:37

We had our ensuite batted out with silencer bats as part of an extension didn’t cause any issues for COC

chez

93 posts

Master Geek

#3017217 5-Jan-2023 10:20

Thanks to you all. Time to get some batts then.

chez

93 posts

Master Geek

#3017859 6-Jan-2023 16:01

I was reading on Gen Less website and it says that the insulation should be as thick as the cavity wall and no thicker. I measured the wall, it's 70mm. Does it mean that I should only use 70mm thick wall insulation? What happens if I put 90mm thick?

tweake

2349 posts

Uber Geek

#3017933 6-Jan-2023 17:31

chez:

I was reading on Gen Less website and it says that the insulation should be as thick as the cavity wall and no thicker. I measured the wall, it's 70mm. Does it mean that I should only use 70mm thick wall insulation? What happens if I put 90mm thick?

all that happens is you waste a couple of dollars buying insulation. the 90mm insulation will perform like 70mm insulation.

Jase2985

13428 posts

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#3018021 6-Jan-2023 19:36

it may not fit in the wall cavity property and cause any wall linings to bow slightly

Backblaze

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esawers

551 posts

Ultimate Geek

#3018086 7-Jan-2023 08:48

A builder told me recently that we shouldn’t insulate internal walls, because it stops heat transfer happening between rooms in the house.. any thoughts? I guess if you have a proper heat transfer system that negates that theory.

The house in question was an art deco with concrete internal walls and as cold as an iceblock, we were talking about rebuilding it like for like with modern materials, which he suggested would be concrete block external walls but wooden framed internal walls.

tweake

2349 posts

Uber Geek

#3018121 7-Jan-2023 10:17

esawers: A builder told me recently that we shouldn’t insulate internal walls, because it stops heat transfer happening between rooms in the house.. any thoughts? I guess if you have a proper heat transfer system that negates that theory.

The house in question was an art deco with concrete internal walls and as cold as an iceblock, we were talking about rebuilding it like for like with modern materials, which he suggested would be concrete block external walls but wooden framed internal walls.

NZ builders suck. they are so used to building low performing homes, they wouldn't know a decent build if it bit them.

in practise even an uninsulated wall stops a fair bit of heat transfer anyway. eg my spare room doesn't really warm up if i shut the door and all the rooms are around it are heated. reality is they leave insulation out to reduce costs then make up excuses and talk smack. (there is builders out there who still complain about having to install ANY insulation into a house.)

concrete walls can be ok, if thermally broken and the house is heated properly (which typical kiwi doesn't do). but concrete is a big expense, there is weight and foundations to consider.

i would be very careful using concrete block unless your talking non structural "brick". kiwis tend to do "brick and tile" very well and its not to hard to give it that art deco look.

chez

93 posts

Master Geek

#3019864 11-Jan-2023 09:46

I got the 75mm thickness batt now. Bradford Gold acoustic wall insulation. I have PVC pipes. How do I put the batt around the plumbing and electrical wiring? I've seen some overseas YouTube videos but I don't know if we have particular building code or regulation in NZ. Should I split the batt and get it right behind and front of the wiring or pipes, simply tucking it in.

Let me know what you think of these techniques.

https://youtube.com/shorts/O2NOhGAYl2s?feature=share

https://www.youtube.com/watch?v=Ev_jSu-Airc

Jase2985

13428 posts

Uber Geek

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Lifetime subscriber

#3019885 11-Jan-2023 10:26

i dont remove sections of insulation like in the video i just cut a split in the and fit it round the obstruction

thenine

37 posts

Geek

#3020443 12-Jan-2023 13:35

chez:

I got the 75mm thickness batt now. Bradford Gold acoustic wall insulation. I have PVC pipes. How do I put the batt around the plumbing and electrical wiring? I've seen some overseas YouTube videos but I don't know if we have particular building code or regulation in NZ. Should I split the batt and get it right behind and front of the wiring or pipes, simply tucking it in.

Let me know what you think of these techniques.

https://youtube.com/shorts/O2NOhGAYl2s?feature=share

https://www.youtube.com/watch?v=Ev_jSu-Airc

It's been a while since I was an insulation inspector but.... 75mm is a good move as if it's too thick you can start popping screws in the gib. The first video is about right although instead of sticking the insulation on the 'open' side of the pipe(s) i'd tuck it so it sits against the gib on the other side. For wall insulation you don't need to worry about pipes, only gas, fire and lights.

The Bahco insulation saws are pretty good, just get the sharpener as they get blunt pretty quickly with wall stuff. If you're using a knife, have a few blades handy.

i like the polyester products over the fibre glass for walls but there's not a massive difference.

thenine

37 posts

Geek

#3020444 12-Jan-2023 13:37

Also if you think you may one day drop a power point on the other side of the wall or something then throw a conduit in there. it's a nightmare trying to drill and fish wire through nogs and insulation.

aucklander

477 posts

Ultimate Geek

#3020758 13-Jan-2023 09:24

I do not believe the building code addresses any insulation in internal walls, apart (maybe) where the "internal wall" is actually inter-tenancy wall, in which case it is subject to different requirements. "Internal walls should not be insulated because prevents heat transfer to the adjacent space" - ha... ha... this is a good one, I believe invented by the industry to justify low cost approach. I added acoustic insulation in shower internal walls (which were actually done with 140mm framing to allow niches to be created into the wall).

I perfectly agree with the impact on wiring, this needs to be taken into account.

chez

93 posts

Master Geek

#3021173 14-Jan-2023 07:37

Thanks to you all. It's good to know that I'm in a right track so far.