Thoughts on this new build insulation

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#2611348 26-Nov-2020 19:11

Arguably running the batts over the top of the joists is preferable, as it means that the timber doesn't act as a 'cold bridge' across the insulation. Timber is substantially more thermally conductive than batts, though less so than air.

There are options with more R value per thickness if you really want to go that route under the walkway, such as foam board, but it costs more especially in small quantities.

LostBoyNZ

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#2611930 27-Nov-2020 16:07

Ah they went in and fixed those, but yeah I understand what you mean by them going over the joists, a thermal blanket.

I really hope the insulation under the walkway and storage area does perform well. Everyone says the ceiling insulation is the most important, which makes sense. With all the small gains you get from various upgrades to windows etc, I imagine a not very good ceiling insulation would lose much more than the small gains give.

The gib is up on the walls and ceiling now, so there's no going back. It was interesting though, we could see next doors which is also under construction, and their pink batts look so carefully installed, no bulges anywhere, cut around the electrical brackets (but only to the depth of the bracket so there's still insulation behind it), wires goes inside the insulation not pushed behind wires etc. They're with Mike Greer, but ultimately I imagine it comes down to the individual contractor and their team.

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timmmay

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#2612052 27-Nov-2020 20:28

Ceiling insulation does make a huge difference. We went from none in our very old house a decade ago when I bought it to blown in wool, which made a HUGE difference. It compacted a bit over time, so I put standard depth pink batts over top, double layer in some places, that made another big difference. Walls made some difference, under floor made some difference mostly due to the vapor barrier I think, double glazing made a difference, but not so much as ceiling insulation. We have lowered ceilings, we insulate the top of the current ceiling, which leaves gaps as the old walls go up higher. I suspect finding a way to insulate in there would make another difference, but diminishing returns.

SomeoneSomewhere

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#2612178 28-Nov-2020 11:21

We had some muppets recently who very carefully cut the insulation around the flushboxes, then stuffed the fire-rated flushboxes full of said insulation.

I have no idea.

Kickinbac

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#2612488 28-Nov-2020 21:44

I saw recently an article where the walkways in the roof was covered with xps foam board to match the insulation rating adjacent, similar to your situation. This is quite a dense insulation board and could be walked on. This was overseas and insulation was R6, think it was in Fine Homebuilding.

LostBoyNZ

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#2612626 29-Nov-2020 12:03

Yeah I'm glad we spent the extra on higher rated ceiling insulation as that seemed to be the cheapest way to make the biggest difference.

Wow someone stuffed the flushboxes with the insulation? :o

Interesting about XPS Foam Board, and that you can walk on it. I'll look into that, thanks!

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Kickinbac

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#2612706 29-Nov-2020 17:27

Found it! Insulated ceiling hatches and walkways.

https://thehtrc.com/2011/air-sealing-attic-walkways-storage

edit: added description and fixed spelling.

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timmmay

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#2612732 29-Nov-2020 19:45

Kickinbac:

Found it! Insulated ceiling hatches and walkways.

https://thehtrc.com/2011/air-sealing-attic-walkways-storage

I did something very like that. The ladder up, some insulation around the side. Up top though I have two pieces of plywood or something similar, with pink batts between them, and wood around the outside. It's pretty heavy so it has hydraulic arms from the back of an old vehicle to help it go up and down. From the house it looks like a white ceiling under the stairs, but does a great job of keeping heat in / out.

LostBoyNZ

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#2613601 30-Nov-2020 20:43

Awesome find with the insulated hatch. As I said to my wife, we have everything there insulated but there's a big hole in the ceiling, the hatch. We do however have the internal walls around the garage insulated too, so maybe it's of minimal effect, but that could be a good DIY project one day.

Sadly despite checking with the builders many times that they'll put double 13mm gib noiseline around the media room, they put double 10mm noiseline around it instead. When I said they've put the wrong gib in and they looked into if they swap it (they'd have to change the doorframe too) they said ITM did calculations for them and they worked out putting R2.8 insulation in between instead of pink batts silencer would give the same or better result as double 13mm noiseline gib on each side. They're going to send through the calculations tomorrow morning so I can see too.

As Pink Batts don't seem to even list the STC rating for their non-silencer batts, it'll be interesting to see and get thoughts on the calculations. I was under the impression the biggest difference for blocking sound is through mass, and I would have thought especially for lower frequencies like bass, a thicker solid surface is better.

Since pink batts silencer doesn't come in r2.8, it's estimated at r1.9 to r2.4, I assume that means they removed all the silencer that was already there and put some other insulation in instead. Although highly possible there isn't much difference with silencer vs normal anyway, but still I can't help but feel this all sounds like a bit of a way around having to re-do the gib and doorframe. If the calculations do checkout though, that's a relief.

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mdooher

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#2613670 1-Dec-2020 07:33

I made my own insulated hatch. Basically put a batt on top of it then lay a piece of the batt plastic packaging on top, stretch it over the hatch, staple it to the edge trim it up and done. looks like a big pink pillow

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Paul1977

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#2613762 1-Dec-2020 09:29

LostBoyNZ:

Awesome find with the insulated hatch. As I said to my wife, we have everything there insulated but there's a big hole in the ceiling, the hatch. We do however have the internal walls around the garage insulated too, so maybe it's of minimal effect, but that could be a good DIY project one day.

Sadly despite checking with the builders many times that they'll put double 13mm gib noiseline around the media room, they put double 10mm noiseline around it instead. When I said they've put the wrong gib in and they looked into if they swap it (they'd have to change the doorframe too) they said ITM did calculations for them and they worked out putting R2.8 insulation in between instead of pink batts silencer would give the same or better result as double 13mm noiseline gib on each side. They're going to send through the calculations tomorrow morning so I can see too.

As Pink Batts don't seem to even list the STC rating for their non-silencer batts, it'll be interesting to see and get thoughts on the calculations. I was under the impression the biggest difference for blocking sound is through mass, and I would have thought especially for lower frequencies like bass, a thicker solid surface is better.

Since pink batts silencer doesn't come in r2.8, it's estimated at r1.9 to r2.4, I assume that means they removed all the silencer that was already there and put some other insulation in instead. Although highly possible there isn't much difference with silencer vs normal anyway, but still I can't help but feel this all sounds like a bit of a way around having to re-do the gib and doorframe. If the calculations do checkout though, that's a relief.

@LostBoyNZ Why would you assume they've already changed the silencer batts to standard R2.8 batts when they weren't made aware of the gib error until after it was up? It sounds to me like they'd still need to rip all the gib off one side to replace the insulation, then re-gib.

I'd want to be VERY sure the calculations stack up, as if R2.8 truly does do a better job with noise then why is Silencer even a product? They'll want to "fix" it in the cheapest and easiest way possible (or if possible try to convince you it doesn't needing fixing at all).

LostBoyNZ

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#2613771 1-Dec-2020 09:44

@Paul1977 Yeah haha we thought the same thing last night so this morning we went and checked and they haven't changed the insulation, it's still silencer. I think there was some more mis-communication though, as it sounds like the installer put standard batts in at first, then before the gib went up they swapped them for silencer. But as I said to them this morning, the silencer is what we asked for originally, so it can't make up for thinner gib, because we'd asked / paid for the thicker gib and the silencer. We're chatting with them later today so it'll be interesting to see what happens.

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Paul1977

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#2613838 1-Dec-2020 10:26

LostBoyNZ:

@Paul1977 Yeah haha we thought the same thing last night so this morning we went and checked and they haven't changed the insulation, it's still silencer. I think there was some more mis-communication though, as it sounds like the installer put standard batts in at first, then before the gib went up they swapped them for silencer. But as I said to them this morning, the silencer is what we asked for originally, so it can't make up for thinner gib, because we'd asked / paid for the thicker gib and the silencer. We're chatting with them later today so it'll be interesting to see what happens.

@LostBoyNZ A quick search of previous threads the consensus appears to be that the thicker gib does more for noise than the batts, but obviously hard to calculate since Pink Batts don't publish the STC for their non-Silencer batts. But double 13mm gib on each side is an additional 12mm gib thickness across the entire wall compared to 10mm gib.

You're well within your rights to get what you paid for, but could the following be an option?

Leave the double layers of 10mm noiseline in place, and put a third layer of noiseline to the interior of the media room. The question would be, and I have no idea, can they do a triple layer of gib or are there specific reasons it can't (or shouldn't) be done?

They'd still need to replace the door frame, which might entail removing and replacing the gib around the door as well - I'm not sure. But if there's no reason you shouldn't do a triple layer of gib this would still work out cheaper, be less work for the builder, and be better noise control for you than your original plan. Would make the media room very slightly smaller though.

Hopefully someone more knowledgeable than me can chime in on whether this is a feasible option.

You also want to make sure they offset the joins on the different layers (so the joins aren't on top of each other) on any additional/replacement gib they put up (too late to check what's already in place).

The below (which I wish I'd looked at before we built) has a lot of info about things other than just noiseline to help (acoustic sealer at corners, acoustic seals for doors, etc). It's an old document, but it probably all still applies.

https://www.gib.co.nz/assets/Uploads/Quieter-Homes-Brochure-2014.pdf

We only did noiseline gib (single layers) and silencer batts, and I'm pretty sure most of our sound transmission is under and around the doors.

LostBoyNZ

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#2613935 1-Dec-2020 13:29

Yeah I learned some interesting things about Pink Batts silencer and Noiseline gib by speaking to technical support people at both companies. The main thing is that their technical team members are fantastic and very keen to help, and Gib have software that calculates the STC rating for any combination of gib.

The end result was that going from double 10mm noiseline gib on each side of our timber frame single wall to double 13mm noiseline gib would only reduce the sound by 2 decibels (so +2 to the STC rating). But adding a 3rd layer of 10mm gib noiseline to one side would increase the STC rating by more, so that is the better way to go, and that's what the builders offered to do this morning.

They also mentioned to check that SoundSeal is being used with the gib, which @Paul1977 that brochure you linked to also details.

When it comes to the door, the brochure says "Use a solid core door with rubber acoustic seals fitted around the perimeter of the doors and retractable self closing sound floor seal on the base of the door". We're part way there, in that we've got a solid core door. I wonder if adding the rubber acoustic seals and retractable self closing sound floor seal can be something we add later. Or at least we can have a convo with the builders about it in a couple of weeks.

While we want to get what we asked for and paid for, and are happy to accept changes for technical reasons (such as not being able to put in the attic trusses above our garage like in the plans), we also don't want to flood them with additional complications when it's something we could do later. Like the insulation for the attic hatch, we might do that later.

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Paul1977

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#2614024 1-Dec-2020 15:17

LostBoyNZ:

Yeah I learned some interesting things about Pink Batts silencer and Noiseline gib by speaking to technical support people at both companies. The main thing is that their technical team members are fantastic and very keen to help, and Gib have software that calculates the STC rating for any combination of gib.

The end result was that going from double 10mm noiseline gib on each side of our timber frame single wall to double 13mm noiseline gib would only reduce the sound by 2 decibels (so +2 to the STC rating). But adding a 3rd layer of 10mm gib noiseline to one side would increase the STC rating by more, so that is the better way to go, and that's what the builders offered to do this morning.

They also mentioned to check that SoundSeal is being used with the gib, which @Paul1977 that brochure you linked to also details.

When it comes to the door, the brochure says "Use a solid core door with rubber acoustic seals fitted around the perimeter of the doors and retractable self closing sound floor seal on the base of the door". We're part way there, in that we've got a solid core door. I wonder if adding the rubber acoustic seals and retractable self closing sound floor seal can be something we add later. Or at least we can have a convo with the builders about it in a couple of weeks.

While we want to get what we asked for and paid for, and are happy to accept changes for technical reasons (such as not being able to put in the attic trusses above our garage like in the plans), we also don't want to flood them with additional complications when it's something we could do later. Like the insulation for the attic hatch, we might do that later.

Sounds like a good solution in regards to the gib.

I would have thought the acoustic seals would be fitted after the door frame was painted. And with a solid door you should be able to make whatever modifications you need whenever you want (may need repainting depending on what's involved). But don't take that as gospel, just an assumption on my part as it's not something we did (didn't know about them when we built).

If the door is over carpet (like ours is) I'm not sure how well a rubber seal at the bottom would work.

Off topic, but why couldn't they do the attic trusses if they were on the plan?

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