Insulation around pipes

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Paul1977

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#270572 15-May-2020 14:00

The insulation is going up in our house at the moment, and where there are water pipes the are just tucking it in behind the pipes.

I've read hear a few times that it's better to cut a slit in that batt so it comes out around the pipe, I asked the installer and he said it wouldn't really achieve anything and they've never done it that way.

I didn't want to make a big deal about it, but was wondering if I should just go in during the weekend and do it myself (i.e. cut a split in the batt and pull it out around the pipes)?

I'm talking about the external walls if that makes a difference.

EDIT: A guide I found on Mitre 10 website says:

Special attention must be given to electrical and plumbing fittings when insulation is installed. Wherever possible, Pink® Batts® insulation should be laid beneath electrical wiring or pipes. However, if the insulation is likely to be considerably compressed in that position, it should be placed over the pipes or wiring.

So now I have no idea, because it doesn't mention cutting the batts to go around plumbing?

EDIT 2: The Actual Pink Batts installtion guide says:

Fit Pink® Batts® insulation tight and close around electrical cables and pipes. It’s important to minimise compression,
gaps and folds in the insulation. For electrical cables and small diameter pipes, partially cut insulation and place around
the cables and pipes

I'm sure I've been told here you can't do that with electrical cable?

So confused!

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#2484456 15-May-2020 14:13

I did the same. The insulation installers were slack when it came around pipes and only cut and installed half the depth of batt from random offcuts. I went on the weekend and used insulation leftover from offcuts which was plenty left and filled it all up. Took photos and showed it to builder as well. Got a apology from Mammoth and some credit from final bill of insulation installers for the horrible job they did on the sections where pipes were running. Also straightened and tidied up the ceiling insulation and other wall insulation sections that were off because OCD kicked in.

Do whatever you want to do man.

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Paul1977

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#2484461 15-May-2020 14:19

billgates:

I did the same. The insulation installers were slack when it came around pipes and only cut and installed half the depth of batt from random offcuts. I went on the weekend and used insulation leftover from offcuts which was plenty left and filled it all up. Took photos and showed it to builder as well. Got a apology from Mammoth and some credit from final bill of insulation installers for the horrible job they did on the sections where pipes were running. Also straightened and tidied up the ceiling insulation and other wall insulation sections that were off because OCD kicked in.

@billgates in my case it's the full thickness batts pushed behind the pipes (so presumably compressed). So you think I should just sort those few ones myself? I just want to make sure that any changes I make are compliant.

billgates

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#2484464 15-May-2020 14:25

Most of ours were not compressed. They were obvious cuts and 40% thickness of normal size batt so it did not even meet the required R value as per law for outer walls. Took me an entire day. I luckily took my own ladder as I originally went to lay and terminate all the low voltage cabling. I was lucky that I picked that weekend with builder to run the low voltage cables as insulation installers had finished all their work day before and council inspection was due on Monday and builders were going to start gibbing straight after inspector left. It is your house and you cannot over do it. There are very few trades you will come across that work attention to detail so do what you can. We are nearly 80% complete now with our build and hoping for house hand over end of June. It is stressful but also fun so enjoy the journey :)

Do whatever you want to do man.

Paul1977

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#2484469 15-May-2020 14:34

Does anyone know if the rules for insulating gas pipes are the same as water pipes in terms of insulation? Can I cut the batt and insulate around the gas pipes?

EDIT: and what's the deal with electrical cables? can the or can't they be fully surrounded by insulation?

DonH

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#2484471 15-May-2020 14:38

Wiring enclosed in insulation may in theory overheat, although I don't think it's much of an issue - it happens anyway with blown-in and spray foam insulation.

Enclosing plumbing in wall insulation is not, in my opinion, worth the effort. The only thing to watch is pipes in exterior walls in freezing areas, the pipes should be on the "inside" of the insulation. Insulation of hot water pipes (lagging) is usually only done for the first metre or two after the cylinder to reduce standing heat loss.

People hear what they see. - Doris Day

Paul1977

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#2484478 15-May-2020 14:54

DonH:

Wiring enclosed in insulation may in theory overheat, although I don't think it's much of an issue - it happens anyway with blown-in and spray foam insulation.

Enclosing plumbing in wall insulation is not, in my opinion, worth the effort. The only thing to watch is pipes in exterior walls in freezing areas, the pipes should be on the "inside" of the insulation. Insulation of hot water pipes (lagging) is usually only done for the first metre or two after the cylinder to reduce standing heat loss.

Thanks @DonH for me it's more that it's compressing the batts and reducing their efficiency rather than wanting to insulate the pipes better.

elpenguino

3376 posts

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#2484501 15-May-2020 15:37

Paul1977:

DonH:

Wiring enclosed in insulation may in theory overheat, although I don't think it's much of an issue - it happens anyway with blown-in and spray foam insulation.

Enclosing plumbing in wall insulation is not, in my opinion, worth the effort. The only thing to watch is pipes in exterior walls in freezing areas, the pipes should be on the "inside" of the insulation. Insulation of hot water pipes (lagging) is usually only done for the first metre or two after the cylinder to reduce standing heat loss.

Thanks @DonH for me it's more that it's compressing the batts and reducing their efficiency rather than wanting to insulate the pipes better.

Batts don't work when they're compressed - for the want of a 20 second slice that can allow the batt to expand around the pipe/cable.

Leaving a batt compressed underneath something like a pipe reeks of slackness, but then insulation installation is a career unlikely to attract the best and brightest.

As said, it's your place, details add up.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

Paul1977

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#2484507 15-May-2020 15:46

elpenguino:

Batts don't work when they're compressed - for the want of a 20 second slice that can allow the batt to expand around the pipe/cable.

Leaving a batt compressed underneath something like a pipe reeks of slackness, but then insulation installation is a career unlikely to attract the best and brightest.

As said, it's your place, details add up.

@elpenguino do you know if it is the same for gas pipes, and also for electrical cables (I have read differing opinions on the electrical side of it).

That said I don't know what they've dome on the electrical side of things, I'll check that out tonight or tomorrow morning.

But the gas line has definitely just had the batts compressed in behind them, can this be treated like a water pipe and just slice the batt to expand around it?

Gibbing is scheduled to start on Tuesday, so I assume the pre-line inspection is being done on Monday. So anything I need to fix needs to be done this weekend.

Froglotion

208 posts

Master Geek

#2484521 15-May-2020 16:20

Yes gas pipe is perfectly fine within the batts. I'd be slicing them all and covering up all of the services if it was my place. If you're concerned about the wires, ask the sparky, it's a quick question and they won't mind answering. Just sounds like they did an average install job on the batts as you say. In theory a circuit should trip long before a wire becomes a heat hazard. Wires you can often just slice the top of the batt vertically, so that the wire doesn't compress the batt.

elpenguino

3376 posts

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#2484523 15-May-2020 16:23

You should slit and expand a batt around electrical cables if you want your insulation to work properly.

The cable won't be able to dissipate as much heat as when in free space so your sparky will de-rate its' current carrying ability - meaning that 20 amp cable carries 16A max (or whatever).

I'm unknowledgeable of regulations in the water/gas area.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

Froglotion

208 posts

Master Geek

#2484524 15-May-2020 16:24

If you're running any draw wires, take photos of them. I took photos of every wall in my place before it was gibbed, was handy when I later wanted to check where i'd have fixings for something.

wellygary

8253 posts

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#2484529 15-May-2020 16:29

Froglotion:

If you're running any draw wires, take photos of them. I took photos of every wall in my place before it was gibbed, was handy when I later wanted to check where i'd have fixings for something.

This + Lots

I walked abound and took a million photos of the walls before the Gib went on,

It costs you a few minutes of time, but will save you a truckload of issues if you want to do wall work in the future,

Paul1977

5001 posts

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#2484530 15-May-2020 16:32

Froglotion:

Yes gas pipe is perfectly fine within the batts. I'd be slicing them all and covering up all of the services if it was my place. If you're concerned about the wires, ask the sparky, it's a quick question and they won't mind answering. Just sounds like they did an average install job on the batts as you say. In theory a circuit should trip long before a wire becomes a heat hazard. Wires you can often just slice the top of the batt vertically, so that the wire doesn't compress the batt.

Thanks @Froglotion I'll swing by tonight and see if what they've done with the power cables. I've just texted the sparky to ask what's allowed and what isn't in that regard.

When you say slice the top of the batt vertically, do you mean do that at top and bottom so the cable runs on the edge of the batt for most of it, bit then gets tucked in where it goes through the dwangs without compressing the batt?

Froglotion

208 posts

Master Geek

#2484549 15-May-2020 16:41

Yeah was just another option i've seen done on sites. You can probably also slice the whole length of the batt and tuck the wire into the batt and close it back up. Batts often don't like coming apart in a uniform manner some times. You'll work out which is your preferred method pretty quickly. It's a good idea to do what you're doing. They won't even notice you've done it at pre line inspection, probably too used to seeing rough jobs done.

You only have to cut the front half of the batt vertically for that above idea too.

Froglotion

208 posts

Master Geek

#2484552 15-May-2020 16:46

Here is my water heater, so by the looks I sliced the front half you can see, and had the pipes tucked into the slot. Rather than cutting the whole thing in half width ways.

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