Warm / Dry / Clean houses - how should it be done in NZ?

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timbosan

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#298830 20-Jul-2022 08:15

Hey all,

I was reading the thread about Positive Pressure sytsems here Positive Pressure Ventilation Systems 2022 (geekzone.co.nz) and it got me thinking, there are lots of threads on geekzone about specific problems (e.g. ventilation), or specific products (heat-pumps etc.), but is there an actual correct/best way to make a home warm / dry and with clean air?

I know warm / dry are someone related, and I know old houses are very different from new builds. So:

* What is the best approach to achieving this on an old home? For example, I have an old cottage, wooden floor boards, no in-wall insulation, it does have ceiling insulation, by end of Aug half the windows will be retrofit double-glazed with the rest to come later. A lot of achieving these goals will have to be retrofitted. But do I need a ventilation system or just a heat-pump? Do I need a separate purifier? etc.? Is it best to start with basics such as a ground sheet?

* Do new builds achieve this with current standards?

Big topic but I hope it gets a lot of information into one place.

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#2944072 20-Jul-2022 08:37

I can tell you what I've done, and what I might do differently. This is my recommended order, it's roughly the order I did things:

Ceiling insulation, more than the minimum spec. Learn how to install it properly or get it done for you. I found ceiling insulation to be much more effective than wall or under-floor, and adding a second layer in the ceiling helped some more.
Vapor barrier under the house if required / practical. This can make a house smell much better and reduce moisture and isn't expensive, but is a pain to install - it has to be pegged down and taped to any piles, for example. Get under floor insulation done at the same time if you want to, otherwise do the underfloor insulation a bit later as I found it didn't help hugely - but we have carpet with a thick underlay.
Good quality extraction in bathroom and kitchen. The bathroom units with a light aren't much good, you want a proper extractor fan from Fantech, Ming Fans or similar.
Heat pump(s) - high wall, floor or ducted (ducted guide here).
Ventilation - ideally heat recovery but positive pressure is ok. Put it on a timer so it doesn't make your house cold in winter / overnight. I put a HEPA filter and a charcoal filter on mine instead of the useless sock filter, charcoal reduces smoke and petrol fume smells significantly. I pull fresh air from outside, rather than the ceiling space as my ceiling space smells. For ventilation to be worthwhile and work the house has to be reasonably well sealed.
Double glazing
Wall insulation. I had the foam pumped into the walls. It worked ok but made a heck of a mess. Even after repainting it looked a bit odd, it was only after a professional full strip and repaint it looked good. I'm not sure I would do it again. They miss many areas, which we can see in the rooms we took the gib off inside.

The order you do them will depend on the house and the budget. If your house is damp prioritise the items that reduce dampness, if it's cold prioritise insulation and heating. Removal of moisture and ventilation is important for every house.

It's quite expensive to do all that and it will take a number of years - it took me about a decade but took my house from a cold, damp house to a very warm, dry house that's nice to live in.

kobiak

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#2944083 20-Jul-2022 09:15

I'd do in the following order:

- fix moister/dampness issues, as it's the worst of all. So underfloor moister barrier, extraction fans, ect.
- insulation top/walls/bottom
- heating
- ventilation
- double glazing

Also I would not underestimate floor insulation.

I had carpet with underlay directly on concrete slab (I'm sure I had topic on GZ for that :)). During west akl winter, without heating - floor temp was around 8-10C (without heating) when it's 2-4C outside. I put XPS boards on the concrete + underlay + laminate - temp never dropped below 13-15C now without heating.

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mattenz

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#2944125 20-Jul-2022 10:43

Probably want to be sealing the windows properly as well, including the voids around the framing.

tweake

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#2944151 20-Jul-2022 11:28

most of the above is fine.

moisture barrier first because it will take a year to dry out the floor and the floor may open up a bit. do as much as you can. if you can only cover 50% you will get 50% reduction in moisture. if you cannot wrap the piles, don't worry about it. make sure the ground is dry first. if its wet sort the drainage/slope etc first. don't forget drain holes in plastic.

do not underestimate floor insulation. your in contact with the floor so it can make a big difference to how you feel. don't skimp on it like most do. the whole ceiling should be a lot more insulation is only relevant when you have low insulation levels. on well insulated houses the effect is a lot less. remember heat travels in ALL directions.

double layer ceiling insulation is cheap to do.

ventilation depends a bit on how well sealed the place is. if its breezy already then ventilation system won't do anything. however i highly recommend sealing the house as much as possible and using a ventilation system. that provides far more consistent ventilation without so much over ventilation.

big thing to look at is the floor. old plank or T&G floors leak air like crazy and pulls tons of moisture in. once its dried out, look at sealing it.

a lot of the really old plaster ceilings can be really air tight, unless someone cut holes in it for lights. make sure you fit led lights as they are a lot more air tight.

heating, there is a lot of options.

wall insulation is the hardest most expensive. i do not recommend the drill holes through the cladding and blow stuff in crowds. even branz has pulled their recommendations on that. remove the gib, pocket install WRB and insulate. regib.

on my place the biggest drop in condensation was after doing the moisture barrier. it was instantly noticeable. the 2nd was after after installing flooring insulation, the 3rd was ventilation system.

Shindig

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#2944211 20-Jul-2022 13:39

Just wanted to say this is a great topic! I will be keeping an eye on it for future reference! Thanks to all who respond

The little things make the biggest difference.

SpartanVXL

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#2944214 20-Jul-2022 14:09

I don’t know if theres a standard thats not being met for double glazing, but in quite a few of the buildings I’ve been in the windows frames are still a problem. Either not sealed properly or maybe just not made of the right stuff, freezing cold and condenses moisture all winter long.

Somewhat of a design flaw in leaking energy, but it must be ticking a box somewhere to keep getting installed like this.

tweake

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#2944217 20-Jul-2022 14:22

SpartanVXL: I don’t know if theres a standard thats not being met for double glazing, but in quite a few of the buildings I’ve been in the windows frames are still a problem. Either not sealed properly or maybe just not made of the right stuff, freezing cold and condenses moisture all winter long.

Somewhat of a design flaw in leaking energy, but it must be ticking a box somewhere to keep getting installed like this.

there is a bit of a story about that and i don't know all the details. but thats actually code. its what the regs allow.

its caused by non-thermally broken aluminium frames and yes it leaks a ton of heat. i think branz has an article showing that a old school style wooden window with single glazing is more efficient than current double glazing aluminium window of the same size.

my understanding is that the industry lobbied to keep the old style aluminium window frames citing cost. ie double glazing was going to cause such a massive increase in cost as it was. which didn't really happen.

this is a perfect example of what happens when govt fails to regulate and allows industries to be the fox guarding the hen house. which of course is one of the basic causes of leaky homes.

edit: i forgot to mention that new insulation regs come out in within the next year. hopefully those dreadful windows will no longer be used.

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Handsomedan

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#2944218 20-Jul-2022 14:29

One thing to think about is replacing Internal Gutters (or Taylor Fascia gutter systems). They create dampness, through channelling any overflow inside the walls.

Replace those, let the walls dry, ensure the house is well ventilated, well insulated and use either a burner of some sort, or a Heat Pump to warm the now-dry air.

If you're replacing gib internally, ensure you pack the walls with insulation. Many homes in NZ were built without adequate insulation and are colder than they should be as a result.

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tweake

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#2944277 20-Jul-2022 14:50

Handsomedan:

One thing to think about is replacing Internal Gutters (or Taylor Fascia gutter systems). They create dampness, through channelling any overflow inside the walls.

Replace those, let the walls dry, ensure the house is well ventilated, well insulated and use either a burner of some sort, or a Heat Pump to warm the now-dry air.

If you're replacing gib internally, ensure you pack the walls with insulation. Many homes in NZ were built without adequate insulation and are colder than they should be as a result.

thats a bit of major work to fix those internal gutter systems.

there is also a bit more to it than "pack the walls with insulation". a lot of older homes have no wrb/house wrap/building paper on the walls. you must provide a means for water that gets behind the cladding to drain away and keep the insulation dry.

Handsomedan

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#2944286 20-Jul-2022 15:24

tweake:

thats a bit of major work to fix those internal gutter systems.

Around $16k of work on a small single-storey 3brm house that's got flat gables front and rear...

We're about to have it done. It's more than just "a bit" major!!!

But - as the moisture guys said to us as they came in and checked our house out - if they don't get changed, rain comes in every time there's a heavy downpour. You may not see it, but you can certainly feel it.

And the comment on packing the walls with insulation was referring to internal walls - not external walls, being re-lined internally. I know that is a major job often requiring re-cladding.

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vexxxboy

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#2944342 20-Jul-2022 15:42

i have a 1964 weatherboard house with insulation in the roof and under floor. The floor is a metre of the ground. We have one huge heatpump in the lounge that heats the whole house . We never get condensation on the windows or i have never had to wipe water off the window sills. The House is warm and dry and it has to get near 0 degrees outside before we need the heat pump on. the difference between winter electricity bill and summer is about $60. i must admit this is the warmest house i have been in .

Common sense is not as common as you think.

tweake

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#2944348 20-Jul-2022 15:54

timbosan:
* Do new builds achieve this with current standards?

one of the things worth mentioning is how border line we run houses.

i'm sure you have seen the gazillion adds and articles saying that you must ventilate, don't dry clothes inside, have bathroom fans, range hoods etc. however i think thats over played a tad.

for eg i have older house with no bath fan, no range hood, i dry clothes inside and do i have moldy walls? no. does my indoor humidity increase after showing, cooking or drying clothes inside? no. they are all fairly minor sources of moisture. the real issue is many homes are borderline damp and it only take a minor sources to go from 'dry' to damp/mold.

so why are they borderline damp. sometimes its not dealing with the major sources of moisture. eg moisture coming up out of the dirt under the house, moisture coming through things like block walls, retaining walls in the basement, raised gardens pushed up against the house walls, poor site drainage (rain not draining away from the house), house surrounded by moisture producing plants, air flow pulling moisture in and finally one of the biggest is failing to heat the whole home.

tweake

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#2944353 20-Jul-2022 16:11

vexxxboy:

i have a 1964 weatherboard house with insulation in the roof and under floor. The floor is a metre of the ground. We have one huge heatpump in the lounge that heats the whole house . We never get condensation on the windows or i have never had to wipe water off the window sills. The House is warm and dry and it has to get near 0 degrees outside before we need the heat pump on. the difference between winter electricity bill and summer is about $60. i must admit this is the warmest house i have been in .

so what temp do you heat the house to?

not trying to attack anyone here but i hear this story a lot. most of the time it turns out to be a case of running the house cold, ie not heating. some people like it cold, but also many are simply just used to it. kiwis have been well taught to put up with it.

however the other factor that can come into play is the low humidity. low humidity means you can be comfortable at much lower/higher temps. plus older homes tend to be drafty which tends to keep them dry.

this is why most moldy homes are auckland/northland, not mainland.

Handle9

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#2944376 20-Jul-2022 16:57

Handsomedan:
tweake:

thats a bit of major work to fix those internal gutter systems.

Around $16k of work on a small single-storey 3brm house that's got flat gables front and rear...

We're about to have it done. It's more than just "a bit" major!!!

But - as the moisture guys said to us as they came in and checked our house out - if they don't get changed, rain comes in every time there's a heavy downpour. You may not see it, but you can certainly feel it.

And the comment on packing the walls with insulation was referring to internal walls - not external walls, being re-lined internally. I know that is a major job often requiring re-cladding.

I’m not sure what insulating internal walls achieves other than sound insulation. Your heat losses are through the building envelope, not internal walls.

lxsw20

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#2944380 20-Jul-2022 17:03

Yeap I've spoken to a few builders who see zero point in insulating internal walls. If the customer wants it and is happy to pay for it they are more than happy to do it.

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