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55 posts
Posted 48 minutes ago
If they run the heat pump they loose the heat right away through those "windows"
And if they can't afford the following power bill it the heat pump will not run for much longer.
What gets me is that this is known for almost eternity but it is still legal in to install such windows and used religiously by mainstream building professionals.

8 posts
Posted 1 hour 16 minutes ago
Agreed - the windows are bad.

But I wonder whether they are helping the situation by not running the heat pump. Is this not also compounding the situation, or do I have it all wrong?

8 posts
Posted 1 hour 30 minutes ago
I have been looking around at ways of retro fitting LEDs to my existing light fittings. I can easily source cheap LEDs running on 12V, but the typical ebay controllers don’t really fit with what I want to do. I like the use of 12V, as there is no voltage risk to the changes – retro fitting 230VAC LEDs would not be possible, and I’m trying to do this on a budget.

So I have had a hunt around and think I can put together a simple circuit to deliver 12V to the lights from a 24V power source, and allow some PWM dimming as well. Chuck in a cheap micro and a couple of extra components and I can get simple power line comms across the 24V – so I could perhaps later build an app to talk to this via a Raspberry Pi, and control the lights from my phone. I reckon I can sell this to the wife :) If I chuck in a couple of batteries, this alone would sell the wife – we have found recently that candles quickly lose their appeal with young kids around.

I’m not too worried about some efficiency loss in the 24V cables, and the circuit will compensate for the input voltage drop. I thought of going to 36 or 48V, but the costs start to rise on the circuit. Our lounge area presently has the largest single circuit, which with LEDs shouldn’t need more than about 60W at 12V, and this will have about 5A over 5m of 1mm² TPS, and will be by far the worst run in the house. According to this post I should expect about 10% loss in the cable, which I think I can live with. Overall it will be far better than the halogens that are in there at the moment. The 24V run would be about 6m, and drop about 3%.

But before I start building all this and changing my lighting system over to 24V, I’m keen to make sure I haven’t overlooked anything that would force a change back to 230V :(

So some questions:
1. Am I re-inventing the wheel? Is there anything out there that is really cheap (<$30 per lighting circuit) that will power, control and dim groups of cheap LED lights (at 12V?)?
2. Have I missed anything obvious that is a potential show stopper?
3. If you were doing this, what might you do differently (please be gentle!)?
4. I only want to install the LEDs once, and not have to change them ever again. Some LEDs are claiming 50,000 hour life expectancy, so a single install seems reasonable – or is this just marketing? Does anyone have any facts that support/disprove these life claims?

Any thoughts would be appreciated!



12 posts
Posted Today, 11:42 AM
Hi there :)

Sorry I only just saw this now!

We have just done the earthworks for our house as we decided to built a small practice cottage first... I'm totally happy to answer any questions - and of course as I mentioned above happy to see if our plans will work for you (might save about $15,000!) - just contact me via our website


12 posts
Posted Today, 11:42 AM
Hi there :)

Sorry I only just saw this now!

We have just done the earthworks for our house as we decided to built a small practice cottage first... I'm totally happy to answer any questions - and of course as I mentioned above happy to see if our plans will work for you (might save about $15,000!) - just contact me via our website


65 posts
Posted Yesterday, 9:47 PM
No problem Michael. I will need to wait until the weekend though, as I'm away before light and back after dark. Two things to note; the front view (the most useful view) has a fence-worth of timber obscuring part of the lower portion of the wall, and the place looks like a construction site (because it is one!), so is not neat and tidy.

19 posts
Posted Yesterday, 8:08 PM
Thanks for that Leonard. Do you have any pictures of your exterior cladding I could see?

65 posts
Posted Yesterday, 4:59 PM
PS: Not using wood or Magroc does not imply an active decision to not use them, rather a reflection of the situation at the time (i.e. they were either not available, or not freely available) and the desirability of certain characteristics of steel.

65 posts
Posted Yesterday, 4:49 PM
Steel is quicker, lighter, (maybe) stronger, lower cost than wood (if used as-is) and is finished the moment it is up, but has the aesthetic compromise you have noted. Steel offers larger unsupported spans than wood, but this is irrelevant unless you need large clear spans and/or are installing conventional ceilings.

Because I needed to keep costs to a minimum, having walling and roofing that was finished inside and out from the start was a significant factor. I have no intention of ever coating the exterior and am happy with that choice. The living side wall face has some stepped detailing with Shadowclad on the exterior that adequately breaks an otherwise monolithic appearance.

I was hoping that I could live with joins on the interior walls, but it hasn't worked that way. Not that it was a bad decision, as the finish is more than good enough for the interim. I have wondered whether it's possible to use car body filling techniques to fill the grooves on the underside of the roof, but I'm in no hurry to try.

I have successfully used cork tiles to clad a wall in a previous house, so that or similar might be an option instead of plasterboard.

Wood skins (as I understand it) means internal and external finishes are unavoidable, thus more cost. If the cost is acceptable, or external cladding is going to be done anyway, then wood may be the better option. Wood is heavier, so this may be a factor if panels need to be craned into position. Wood (for a roof) will not span as far as steel without additional structural support. If there is now a source in NZ of panels that are essentially whole (or almost whole) sides of houses as is available in the USA and Europe, that is a something of a game changer. I'm not sure what I would have done if that option had been available.

Wood (because of the additional mass) might be better than steel for acoustic damping, but I'm guessing.

486 posts
Posted Yesterday, 4:02 PM
Hello Michael H

I looked into all these options for a build in Christchurch, and can comment as follows:

Thermospan EPS gives you the most cost effective roof system, using raking ceilings designed to say 5m spans with a 250mm thick profile. Design around the characteristics of the material which suits simple gable or monoplanes and not complex hip roof layouts.
The down side is the metal profile to the ceiling gives a ‘commercial / industrial’ effect which is in conflict with a traditional smooth Gib. Ceiling but the cost saving is in about 10% compared to the Magroc equivalent.

For the walls, I used Magroc.
A proprietary high build finish covers the exterior joints giving a smooth textured surface and conventional stopping is all that is required to the interior joins.

For ceiling lights, if you chase in at the joins, the wiring is easy, but be sure to use the correct cable insulation in contact with polystyrene – watch down lights for reduced insulation value and use IC-F not the cheaper incorrectly rated fittings. Pre-planning the cabling is strongly recommended with the electrician progressively linking with the builder as the wall panels go up.

It takes a little time for the builder to come to grips with the system and pre- training with Magroc is to be recommended – starting the wall panel fitting is the most critical construction element – the first panel must be exact in plane, vertical and true or all other panel additions will progressively wander away.

All other SIP have limitations that you have already picked up on and I estimated a 10% cost saving compared to stick building with 140 studs for the equivalent R value.

Best regards - Rex

19 posts
Posted Yesterday, 8:20 AM
Thanks for the Magroc link Leonard. What are your thoughts on the difference between the metal sheet versus "wood" panel SIPs? Thermawise said they hadn't found a way to get rid of the grooves down the wall where the SIP panels meet apart from putting gib board up over them.

65 posts
Posted 24 Jul 15 3:33 PM
Well now. After reading some of the most relevant determinations, it appears that my earlier conclusion is not correct; there are indeed possibilities. I think that reading determinations 2006/72, 2007/109, 2013/055 and 2014/025 carefully will provide all or most of the answers.

Btw - I reckon that John Gardiner is a legend, and that his determinations are works of art.

65 posts
Posted 24 Jul 15 3:10 PM
Also search for "container".

65 posts
Posted 24 Jul 15 11:11 AM
This has been very well covered by the Determinations issued by the Department of Building & Housing (seems to be MIE now). Go to and search for "vehicle". The bottom line appears to be that unless the item is genuinely mobile or used for genuine short term storage, you're out of luck.

65 posts
Posted 24 Jul 15 10:57 AM
FYI - one possible alternative to steel-faced panels are these Techncial manual here

55 posts
Posted 23 Jul 15 2:24 PM
This is something to watch for those who still think that
New Zealand standard aluminium windows are fit for purpose. The reality is that most are not.

17 posts
Posted 22 Jul 15 8:34 PM
gotcha - AAC panel used as a floor - done it heaps - even as a roof with an fibre-reinforced acrylic topping (but more recently using skellerup rubber replacement product)

I've seen it done with both 50mm and 75mm but the latter lets a builder sleep easier at night.

You're right $75psqm is too much - which part of the country are you?

1 posts
Posted 22 Jul 15 8:32 PM
Hi there, I'm wondering if you took this any further? We are currently looking into doing the same but there's very little direction available online. Much appreciated!

13 posts
Posted 22 Jul 15 6:10 PM

I was watching an old episode of Grand Designs the other day and saw a house built with cross laminated timber (CLT) panels that got me interested, then just read today about a house on Waiheke constructed using them. I know they are still pretty new to New Zealand but I was wondering if anyone has any experience with the CLT panels from XLam? What would their thermal performance be like? They have a lot of mass compared to a standard timber construction. Any idea how they would compare costwise with SIP's?

3 posts
Posted 20 Jul 15 5:43 PM
It's must to compare the price,reliability ect,i have a website,you can see by youself

3 posts
Posted 20 Jul 15 5:39 PM
I think this is a technical issue, you can take a look at the renesola to ask customer service staff(, maybe they can help to you

2 posts
Posted 20 Jul 15 2:50 PM
Not there exterior plastering, same AAC panels but laid flat as a floor

7 posts
Posted 20 Jul 15 1:32 PM it! i've already made a few quote enquiries for new windows now, both with german and new zealand suppliers. in case the german option is viable ( including shipping costs ), i will post the results here for everyone...

55 posts
Posted 20 Jul 15 1:26 PM
On the issue of airspace, 6mm is not great idea at all, as there is a big difference between R.32 and R .37.
If 6mm airspace was any good they would use it in Europe for triple glazing to avoid the glass units being so thick as they are with triple glazing.
Of course Metro and the retro fit companies would not say that 6 mm is not good because all they want is to sell their retrofits. If they would tell the clients the truth about retro fits a lot of them would back of.
And they don't care how it performs
The other issue is with bigger glass and small air space is that they one glass can touch the other.

One more big retro fit issue in traditional timber joinery is the fact that IGU,s need a drained and vented rebate.
If you let it sit in unventilated damp or wet rebates it WILL fail.

7 posts
Posted 20 Jul 15 12:09 PM a post scriptum: because of a combination of your answers ( which match the rest of my research ) and what installers have said, i now pretty much accept i have to replace the entire windows rather than retrofitting them. doing some more research on overseas products ( germany ) before probably committing to new zealand installers because of price...thanks, tobias

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