NZ house building is there a light at the end of the tunnel?

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#2663423 27-Feb-2021 18:55

k1w1k1d:

Is the standard NZ house with Gib, 90x40 framing, vapour barrier, external cladding, and some form of insulation shoved in an acceptable building method to start with?

Quite a bit of the wall has thermal bridging through the frame, so lowers the overall R value of the wall.

140x40 framing allows thicker insulation to be installed, but still has the same thermal bridging.

What alternatives are there at an affordable price?

Possibly structural integrated panel systems. Might cost more in materials, but might be suitable for mass-produced but customisable kitsets.

Ge0rge

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#2663435 27-Feb-2021 19:20

My olds recently built, and used 190x40 as the top and bottom plates, with 90x40 studs which were staggered along the wall. Insulation was then weaved along the wall, meaning there significantly fewer thermal bridges from inside to out. Seems to have worked very well - viewing the walls with a thermal camera doesn't show the normal "grid" pattern of heat loss like a typical build.

Jase2985

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#2663456 27-Feb-2021 20:17

Ge0rge: My olds recently built, and used 190x40 as the top and bottom plates, with 90x40 studs which were staggered along the wall. Insulation was then weaved along the wall, meaning there significantly fewer thermal bridges from inside to out. Seems to have worked very well - viewing the walls with a thermal camera doesn't show the normal "grid" pattern of heat loss like a typical build.

how much more did that cost over code?

eracode

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#2663472 27-Feb-2021 20:54

Ge0rge: My olds recently built, and used 190x40 as the top and bottom plates, with 90x40 studs which were staggered along the wall. Insulation was then weaved along the wall, meaning there significantly fewer thermal bridges from inside to out. Seems to have worked very well - viewing the walls with a thermal camera doesn't show the normal "grid" pattern of heat loss like a typical build.

I guess they would have needed 190x40 studs at the corners and where there were openings such as doors and windows?

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Ge0rge

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#2663479 27-Feb-2021 21:09

Not 100% sure about the details, I just remember the old man saying how they were doing the walls. Certainly it would have cost more, but definitely worth it from the results.

neb

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#2663514 27-Feb-2021 22:04

Ge0rge: Seems to have worked very well - viewing the walls with a thermal camera doesn't show the normal "grid" pattern of heat loss like a typical build.

Ooh, I'll have to do that after the Casa de Cowboy redo is finished and it gets colder again and report results, hadn't thought of that. My most recent use for it was to spot possums in the fruit trees at night...

Jase2985

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#2663616 28-Feb-2021 07:33

unless it was in the central platau or in the alps i justs cant see the benefit over 140mm framing. we just dont get cold enough in NZ.

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gzt

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#2663633 28-Feb-2021 08:54

Depends on many tbings. Wind can make a big contribution to thermal loss.

k1w1k1d

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#2663653 28-Feb-2021 10:35

Ge0rge.

Haven't heard of that construction method. Do you have any photos of the framing before gib and cladding were installed?

olivernz

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#2665774 28-Feb-2021 16:05

What you can also do is 140mm stud then air barrier then another batten at 90 degree angle with more insulation (and cables) and then gib. Or do it with 90mm if you want to save but then the thermal bridge is just 40x40mm at intersections

eracode

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#2665807 28-Feb-2021 17:01

olivernz:

What you can also do is 140mm stud then air barrier then another batten at 90 degree angle with more insulation (and cables) and then gib. Or do it with 90mm if you want to save but then the thermal bridge is just 40x40mm at intersections

Probably just me, sounds interesting but I find that description hard to visualise or follow. Maybe you could elaborate?

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Jase2985

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#2665814 28-Feb-2021 17:13

here are some examples

https://zeroenergyhouse.co.nz/walls

neb

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#3257148 7-Jul-2024 18:43

neb:
Ge0rge: Seems to have worked very well - viewing the walls with a thermal camera doesn't show the normal "grid" pattern of heat loss like a typical build.
Ooh, I'll have to do that after the Casa de Cowboy redo is finished and it gets colder again and report results

And I forgot about it until now... so this is an internal wall, you can clearly see the thermal bridging from the studs (the big white square in the middle is a rare unsigned Van Gogh which is picking up the warm air flow from the heat pump):

It's not actually as dire as it seems, the camera is picking up a few degrees difference, and even the smallest thing shows up in the false-colour images. Here's another example, taken from outside, of the ranch slider/window, note the single strip at 12.5 degrees, that's the metal strip at the edge of the uPVC doors that ensures there's a tight seal without risking the uPVC, it's acting as a thermal bridge into the inside:

The thermal drapes are still on order, I expect that figure to go down a bit once they're installed.

tweake

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#3257151 7-Jul-2024 18:52

neb:

good pics. good demo of why homes tend to get mold in the bottom corners. a lot of homes don't have insulation in the corners.

neb

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#3257169 7-Jul-2024 19:15

Yup, there'll be a big thermal bridge of studs in the that corner. However it's also the bit of the room that's most shielded from air flow from the heat pump, so that's not helping. The glowing bit at top left is a metal curtain track which is picking up the heat a lot more than the wall right behind it.

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