[bob_the_engineer]

Let me start by saying I think old kiwi houses are fantastic! There is a slight problem and that’s the kiwi attitude to housing (only from a UK perspective).

Many kiwis don’t seem to mind being cold, much like the seasonal diet, seasonal living is a way of life for many. I’m not saying this is a bad thing, I think people from the UK are used to being cosy, they really aren’t very tough when it comes to cold n damp, and that’s not a bad thing either. It’s just perspective and choice, and I for one think personal choice is important (and so is a seasonal diet).

So your from the UK, your in NZ and this cold damp house is giving you chest infections, mould is growing on the walls and your getting more depressed about it by the day. The kids are coughing and the dog keeps getting in your bed. Now your counting the days until summer arrives, I guess lots of us (not so hardy folk) have been there!

Well this post is really about the numbers, I know people sometimes blame this on living in a house made of wood, but that’s not really anything to do with it.

I also know lots of people go blank when you start rolling numbers in front of them, lots of people hated science at school, and I’ve had one too many of my friends eyes glaze over, once I start ranting; I no longer think everyone finds subjects like thermal conductivity gripping stuff. This post is really for those friends who want to know enough to keep warm and have no intention of allowing themselves to be bored to death by some sad dull engineer!

I’ll do my best so here we go….the numbers are dramatic so keep an eye on them!

OK here we go, hope its not too dull.

When you touch something it wants to be at the same temperature as you, it’s called potential but nothing to worry about.

Put your hand on a sheet of metal it feels cold, that’s because it has a low resistance to the flow of heat, so it tries to warm up quickly,,, pulling heat off your hand makes your hand feel cold, this has “low resistance to heat flow”

Put your hand on a blanket and your hand feels warm, that’s because it has a high resistance to the flow of heat, so it tries to slow down the flow of heat, holding heat on your hand makes your hand feel warm, this has “high resistance to heat flow”

Now we have some terms “high resistance to heat moving” and "low resistance to heat moving” so lets throw in the numbers.

Lets call it “resistance to letting heat escape” so lets look at some materials, remember low numbers are bad!

Material: Brick “resistance to letting heat escape” 1.5
Material: Wood (oak) “resistance to letting heat escape” 6
Material: Polystyrene expanded “resistance to letting heat escape” 33
Material: Air “resistance to letting heat escape” 42
Material: Insulation “resistance to letting heat escape” 62

Something you have to note is..

Air, the air inside the wall gap, its very good at keeping you warm (42 ehh), the only problem is it tends to move! Often replacing itself with cold air. It tends to move quicker in wood houses too.

You may find it a surprise that brick appears to let the heat out quicker than wood, I know it doesn’t feel like that,, if the brick is 4 times thicker that the wood (which it usually is) then they are the same as far as letting heat out goes,,,, the big difference is the brick tends to hold the air in the wall gap, compared to wood. The warmth of a brick house comes from the trapped air! Not the brick.

Just look at the numbers here brick 1.5, wood 6 and insulation 62!!!

So a lets compare walls and warmness eh lol

So you choose to build the thickness of your wall on how warm it will keep you, all these walls are the same from a “keeping you warm” point of view, only the thickness is different.

A wall made of insulation 1 foot thick
A wall made of solid Brick 41 foot thick !
A wall made of solid wood 10 foot thick!

All just as good as one another at keeping you warm!!!

These numbers may not be 100% accurate, lots of things aren’t factored in, double skin and trapped air……… but they are ball park and I’m sure you’ll agree they really are amazing. (well maybe not amazing lol).

Well now for the good news, its not that expensive and its really not that hard to get a kiwi house and make it snug. I have to say it makes one hell of a mess!

You need a hammer, a screwdriver, a pile of plaster board and a pile of insulation.

Rip the plaster board off, put the insulation in, screw/glue the plaster boards in place, then call a plasterer to finish the job off. A winter won’t be the same again!

I can go on (at length) about how to do this, but I guess I’m boring enough so I’ll only do it if I’m asked to.

Its summer, your off work so drive your OH up the wall with your latest DIY project and look forward to a cosy smug winter.

One pointer, completely ignore the NZ building regs about how much insulation to use, measure the gap behind the plaster board and fill it with as much as it can bear, the regs give a minimum and it’s a false economy, although if you let your builder choose the insulation level in your new house that’s just what you’ll get… see I told you I was boring LOL

Don’t hesitate, renovate Bob

[cathgates]

Thanks for that Bob, moving to 'a town near you', next year, warming up the house will be a priority for me!!!

Cath X

[Syed]

Thanks....I would love this modification..

[victoria]

Thanks for the "in depth" explanation. I personally found it fascinating & very relevant.Good on yer for supplying a "ooh let's do something different over christmas" project. Have a good one yourself.

[thezorbster]

Insulation is the first thing we're going to be doing to our house when we move in. Well, when I say we, I mean the nice people from Airfoam.

[incredible hulse]

You forgot the second mortgage to pay for the paint over here after the job is done

[Tia Maria]

bob the engineer wrote:

I can go on (at length) about how to do this, but I guess I’m boring enough so I’ll only do it if I’m asked to.

Please do!

Wouldn't mind getting your opinion on the insulation they inject into houses. I've had some people say its great as you don't have to go to all the expense of redecorating the interior and others say its bad for trapping moisture and makes your wallpaper come off and your paint peel.

Wood (oak) “resistance to letting heat escape” 6
Slippers “resistance to letting heat escape” 23 :)

I have to wear footwear on wooden floors, especially the ones with the wind blowing up through them.

By the way, I've just noticed you have a large amount of green boxes for quite a small post count - does that make you one of our wisest members!?

Great info, off to add some more .......

Cheers

Tia

[Lupin]

Nice post Bob :)

We opted for 'silencer' batts throughout our house as one winter in a Kiwi villa brought the matter sharply into focus. The architect, the project manager and the builder all thought it was overkill ... but I'll be the one enjoying the "cosy smug winter" in a few months :)

[katiejay]

As we'll be spending our first kiwi winter in a rented house, any tips for winterising the property without any structural changes? I looked in Spotlight today and saw some Australian wool blankets, for example, but they were about $200! Should I get some in the sales???:uhoh

[Tia Maria]

A few spring to mind:

1) Block up your chimney (if not in use!)

2) Buy rugs for wooden floors (many kiwis I've met then remove them for summer)

3) That sticky insulation stuff for the gaps around sash windows

4) Sausage dogs for the gaps under the doors

5) Always have something on your feet

6) Dehumidifier - as its a lot easier to heat a 'dry' room, plus you will have less damp on your curtains and bedding (the children get it on their pillows, I think maybe they dribble at night!)

7) Close curtains just before it gets dark and open them the minute the sun is out.

8) We stopped using our unflued gas heaters and we had a lot less condensation on the windows - but they were very useful as a back up for when we had a power cut

These are all little simple changes but can make a big difference. Also make sure whatever heating you have is on a timer, there is nothing worse than having to get up to turn the heating on!

Cheers

Tia

[pinkpiggy]

Bob, Excellent post and very useful. :nice1

Tia, great tips. This was the kind of information we were given when we moved over from the UK and will be really useful for any newbies. :D

[PeteS]

We are in the throws of building, and when we started the project we thought we'd get a local builder to do it. Now, the rules have changed in the last twelve months, but the initial reaction of three different builders to our requests for Double glazing with uPVC frames, Concrete tile roof, R5 pink batts in the roof, Insulated floor slab, Insulated walls built with airated concrete, Central heating, was "you don't need that, you need......"

Me and her indoors, without saying anything to each other, just got up walked out of one builders office. It was so frustrating trying to change the Kiwi perceptions that I'm now project managing it myself.

On a similar vein, we wanted some copper guttering and down spouts. We found a company that did it, and the first words the rep said were "Ooooh, copper's expensive, you need..."

[kanatakiwi]

Our house in Auckland which was built in 1992 so not that old, has a second storey (what we would call a half storey in Canada) where the walls are about 5 feet high and then a slanting roof for the rest of the wall. on each side of the upstairs there are attic spaces. When I look in there I can see lots of daylight where the metal roof touches the outer walls of the foundation. Is this normal? I was shocked because when the wind blows its like a wind tunnel in these attic spaces.

I wanted to put batt insulation to stop this but the guy who came told me no I should not do that, wasn't necessary. He also didn't think the attic walls needed insulating and as to my idea to put the pink batts in and cover with a roll of plastic he said don't do that or your house will sweat and the walls will get damp. Is he right? I remember in Canadian houses the insulation was held in place with plastic.

Any advice here, the upstairs is freezng because of all the cold air coming in through these "air spaces".
G

[katiejay]

7) These are all little simple changes but can make a big difference.

Thanks, Tia - I'd not heard of most of these so I think quite probably you will be a lifesaver! (maybe literally!!).
Thinking of lighting the woodburner today, in fact, as it's so cold, so we will definitely need every one of your tips in the winter. I have saved them as a Word document for later use!

Katie :uhoh

[Tui2too]

>> Any advice here, the upstairs is freezing because of all the cold air
>> coming in through these "air spaces".

Hi G...

Glenn here, Tui2too's OH. It's nice to be close to nature...but not that close. My wife gets tired of hearing me talk about coming home at lunch from teaching in Dannevirke seven years ago and being able to see my breath on the side of the house that wasn't getting the noon sun - *inside* the house!! I thought winter camping in Canada set the gold standard for cold until I lived in a classic NZ villa in winter.

With all due respect to that NZ contractor, I think you're entitled to a warm cozy house. The air leaks from your upstairs area into those knee wall 'wind tunnels' are sucking the warm rising air right out of the place. I think your best option is to completely seal the inside walls, storage doors, windows, etc. from the inside so the warm upstairs air can't be stolen away. This way you won't have to insulate the outside of the knee walls themselves, nor the areas where the metal roof touches the exterior walls.

Insulating the cold side of the knee walls properly would be a major chore, as you'd have to insert pink batt inside them...provided they were already wide enough to accept the batts, and that you also wouldn't have to construct the 'other side' of the knee wall (assuming it's not just one piece of wood thick, for instance).

That said, the contractor is correct in that simply placing batts on the outside of the knee walls and then covering them with plastic is the wrong way to install the plastic. The rule is that the plastic always goes on the *warm* side of the insulation, to prevent the warm air from coming in contact with the cold outside air. Placing the plastic on the outside of the batts on the other side of the knee walls will allow the warm air to pass through the batt and contact the cold plastic and - voila! => instant condensation problems and water damage.

Hope this helps. Don't give up your good fight to stay warm in the NZ winter.

P.S. - If we *DO* get down there, my plan is to fill half a container with bags and bags of R20 pink batt, and you can have first dibbs on whatever we don't use!

[kanatakiwi]

>>

Insulating the cold side of the knee walls properly would be a major chore, as you'd have to insert pink batt inside them...provided they were already wide enough to accept the batts, and that you also wouldn't have to construct the 'other side' of the knee wall (assuming it's not just one piece of wood thick, for instance).


P.S. - If we *DO* get down there, my plan is to fill half a container with bags and bags of R20 pink batt, and you can have first dibbs on whatever we don't use!

Well of course the knee walls are just one piece of wood thick! (well at least they didnt just nail the jibboard to the framing. )
and that's why I was wondering about covering the insulation with plastic. sounds like it would have to be covered with wood?

arrgh!! could be needing your leftover R20. also since we use those attic spaces for storage, do we just forget about insulating where the roof meets the outer wall? sigh. OH is not much help, he grew up in houses like this and says things like "why do we have to insulate under the house, I dont find the floors that cold." :roll

[Björnsdotter]

winter in nz.
(live in a old cottage)
you get home from work, take a shower and get dressed in longjohns and singlette and track suit and wear socks and slippers. Have your dinner in front of the fire. Then off to bed already at 19.00 and watch TV from under the quilt! when fire goes off then house is cold fast!
You make sure NOT to drink something so you have to get up in the middle of the night since your bum will freeze to the toilette seat!
In the morning when the alarm goes off you get out to a kitchen that is only 5-10C. Warm at work so it is like coming to like heaven! :)