Spray Foam Insulation

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#1199869 18-Dec-2014 12:34

I considered going down this path also, but decided that because of the shrinkage and because the installers are essentially working "blind" when they install spray foam insulation, that I'd rather rip down all the gib and install insulation myself.

The advantage was I could close up every single little gap, and install conduits for extra power points and network outlets.

The disadvantage is a lot of mess to deal with, and a big job re-gibbing.

Whatifthespacekeyhadneverbeeninvented?

timmmay

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#1199874 18-Dec-2014 12:47

DK, how much difference did wall insulation make for you?

AACTech

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#1199897 18-Dec-2014 13:10

The advantage to the proper closed cell insulation is that moisture is not an issue whether you are heating or cooling your dwelling.
As water and humidity does not pass through it does not promote the growth of mold which is a very big issue in New Zealand
Air does not pass through.
It is water-blown and its cells are filled with air.
Once it has cured after 24 hours it is inert and does not shrink or expand.
As it is rigid it contributes to the structural integrity of the building. I think I like this idea.
All the other types are subject to sagging and water damage.
It is not attractive to rodents and insects.
By removing the interior wall

What's not to like about it ? The immediate expense yes but recovered by year round savings on heating and cooling. It solves a number of problems in one go.

As I've already mentioned the only down side I can see is finding the qualified tradesmen to correctly install it and oh yes and maybe the local council.

I have no idea what product Airfoam was and it seems neither does any one else. Maybe it was a UFFI (urea formaldahyde foam insulation)?

mattwnz

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#1199945 18-Dec-2014 13:49

Don't you need building consent to take off the gib on external walls and put in insulation? Probably worth it to check, because you may not have insurance cover if you need to claim for something that hasn't had a consent.

If I had a big budget for insulation, I may look at something like XPS http://www.forman.co.nz/products/Insulation/Thermal-Insulation-Residential/Walls

jonathan18

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#1199966 18-Dec-2014 14:01

AACTech: The advantage to the proper closed cell insulation is that moisture is not an issue whether you are heating or cooling your dwelling.
As water and humidity does not pass through it does not promote the growth of mold which is a very big issue in New Zealand
Air does not pass through.
It is water-blown and its cells are filled with air.
Once it has cured after 24 hours it is inert and does not shrink or expand.
As it is rigid it contributes to the structural integrity of the building. I think I like this idea.
All the other types are subject to sagging and water damage.
It is not attractive to rodents and insects.
By removing the interior wall

What's not to like about it ? The immediate expense yes but recovered by year round savings on heating and cooling. It solves a number of problems in one go.

As I've already mentioned the only down side I can see is finding the qualified tradesmen to correctly install it and oh yes and maybe the local council.

I have no idea what product Airfoam was and it seems neither does any one else. Maybe it was a UFFI (urea formaldahyde foam insulation)?

Would you still not have the issue identified above, that of the foam shrinking over time?

We had Airfoam in Lower Hutt install their product in our last house, and had the same results and reservations as timmmay. We found the polythene on the ground and recylced plastic under-floor insulation FAR more effective in reducing heat loss and damp (a big problem in the area we lived in, with a high water table). The foam made a negligible difference to warmth, though I guess much of this could be down to the flaws in the installation method used.

I do recall that airfoam contained formaldahyde; apparently one of the reasons they required you to air the house out for a decent period afterwards! Not the nicest thing to be surrounded by.

Whether different variations of foam and alternative installation methods can mitigate many of these problems, I think I'd stick with something more conventional - for our current house I'm waiting to win Lotto to be able to do afford to do so via ripping current wall linings and then re-gibbing, using a more conventional product.

Hammerer

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#1199982 18-Dec-2014 14:31

The problem with only insulating between the studs and dwangs/nogs is that the thermal barrier is breached/bridged by the wood and nails. This is the same issue with ceiling insulation like batts. Where they are used it is not unusual to see visible signs of the thermal bridging provided by the framing. The internal wall or ceiling surfaces with wallpaper show a lighter or darker colour. Mould and mildew can also be form where the room is cold enough or there is enough moisture in the air or condensation on the walls.

The foam or batts will prevent convective transfer by preventing air moving in the otherwise empty spaces but they don't prevent heat and moisture transfer through the framing. An effective method should do both and usually requires some sort of blanket that covers both the framing and the spaces. But this is real difficult to do properly for walls so most of us accept the compromise and put up with the bridging and gaps.

"Gaps around the edges of insulation, either on all four edges or with gaps on both sides and a double height gap at the top, will reduce the effective R -value of the insulation by approximately 3% for every 1mm gap." That's just one useful bit of info contained in the relevant documents that are available online. They also have some useful pictures to illustrate how to install insulation properly:
NZ Standard 4246:2006 Installing insulation in residential buildings
Guide for retrofitting wall insulation

PS the standard doesn't cover "Expanding in situ foams" and some other forms of insulation e.g. acoustic.

AACTech

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#1199985 18-Dec-2014 14:36

Haha ! So Airfoam used UFFI (urea formaldehyde foam insulation). One more question answered.

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timmmay

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#1199988 18-Dec-2014 14:38

AACTech: The advantage to the proper closed cell insulation is that moisture is not an issue whether you are heating or cooling your dwelling.
As water and humidity does not pass through it does not promote the growth of mold which is a very big issue in New Zealand
Air does not pass through.
It is water-blown and its cells are filled with air.
Once it has cured after 24 hours it is inert and does not shrink or expand.
As it is rigid it contributes to the structural integrity of the building. I think I like this idea.
All the other types are subject to sagging and water damage.
It is not attractive to rodents and insects.
By removing the interior wall

Those sound great in theory, but I don't trust anyone in NZ to actually understand what that means or adhere to it. They may tell you it does all that whereas fact may be different. Plus the airfoam guys were just sloppy.

mattwnz

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#1199994 18-Dec-2014 14:53

Hammerer: The problem with only insulating between the studs and dwangs/nogs is that the thermal barrier is breached/bridged by the wood and nails. This is the same issue with ceiling insulation like batts. Where they are used it is not unusual to see visible signs of the thermal bridging provided by the framing. The internal wall or ceiling surfaces with wallpaper show a lighter or darker colour. Mould and mildew can also be form where the room is cold enough or there is enough moisture in the air or condensation on the walls.

The foam or batts will prevent convective transfer by preventing air moving in the otherwise empty spaces but they don't prevent heat and moisture transfer through the framing. An effective method should do both and usually requires some sort of blanket that covers both the framing and the spaces. But this is real difficult to do properly for walls so most of us accept the compromise and put up with the bridging and gaps.

"Gaps around the edges of insulation, either on all four edges or with gaps on both sides and a double height gap at the top, will reduce the effective R -value of the insulation by approximately 3% for every 1mm gap." That's just one useful bit of info contained in the relevant documents that are available online. They also have some useful pictures to illustrate how to install insulation properly:
NZ Standard 4246:2006 Installing insulation in residential buildings
Guide for retrofitting wall insulation

PS the standard doesn't cover "Expanding in situ foams" and some other forms of insulation e.g. acoustic.

You could stagger the studs. Ceiling you can have two layers that go over the ceiling framing. But having 140 framing and over insulating should offset any the thermal loss from the timber framing. But timber does have some insulating properties, and it is a thermal break. You can always have the insulation layer on the outside of the building, like you can do with some of these polystyrene cladding systems.

If people want decent info on this subject, this is the website to go to, and they have a forum discussing just insulation in NZ! www.designnavigator.co.nz

mattwnz

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#1199996 18-Dec-2014 14:55

timmmay:
AACTech: The advantage to the proper closed cell insulation is that moisture is not an issue whether you are heating or cooling your dwelling.
As water and humidity does not pass through it does not promote the growth of mold which is a very big issue in New Zealand
Air does not pass through.
It is water-blown and its cells are filled with air.
Once it has cured after 24 hours it is inert and does not shrink or expand.
As it is rigid it contributes to the structural integrity of the building. I think I like this idea.
All the other types are subject to sagging and water damage.
It is not attractive to rodents and insects.
By removing the interior wall

Those sound great in theory, but I don't trust anyone in NZ to actually understand what that means or adhere to it. They may tell you it does all that whereas fact may be different. Plus the airfoam guys were just sloppy.

Are you pulling the old stuff out of the walls, and putting in higher R value insulation?

timmmay

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#1200000 18-Dec-2014 15:14

If you're asking me - nope, not around the whole house. As I happen to reline rooms yes I pull the foam out and put in pink batts or similar. The foam in there's better than nothing.

mattwnz

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#1200020 18-Dec-2014 15:42

timmmay: If you're asking me - nope, not around the whole house. As I happen to reline rooms yes I pull the foam out and put in pink batts or similar. The foam in there's better than nothing.

Yes I meant on the walls where you had removed the lining. No point in removing the other, unless you are replacing the wall lining, as most of your heat loss is through the ceiling or through the single glazed windows anyway. We had a quote for that pumped in foam system for a few uninsulated rooms and it was very expensive, and didn't work out as cost effective, compared to putting in under floor insulation, and more insulation in the roof, and perhaps even putting in some insulating glazing units.

timmmay

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#1200040 18-Dec-2014 16:19

Proper double glazing is really expensive, around $3K per window or door I've found. Ceiling insulation for a whole house can be done or improved for less than that.

Distorter

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#1200331 19-Dec-2014 08:59

Seen some good wall fires from the foam insulation reacting with electrical cables and sockets. Have been to jobs where we have had to re-run circuits because the foam can absolute destroy electrical cable, I am not sure what type of foam it is but polystyrene under-house insulation can have the same effect if not installed properly.

gazbo

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#1200353 19-Dec-2014 09:32

Spray type foam will shrink away from the framing during setting which leaves uninsulated gaps at framing lines that leak heat to the exterior.

Depending on your finish to the internal linings and the type of external cladding you have, you will get better performance by removing either of these two linings and install a standard fitted product such as batts. This is more expensive now but will be paid back in power savings over time.

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