Do all houses now need underfloor and ceiling insulation cavities?

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rayonline

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#232052 27-Mar-2018 09:40

Maybe the weather has cooled a bit still ok here till we get the storm.... and the temp drops a fair bit.

I know NZ homes don't have a good reputation with insulation. Our house is maybe 40yrs old and the front of the house (lounge) has a high pointy roof with no accessible cavity. So insulation isn't even possible. Are these still allowed in NZ new builds? Like this image:

http://www.highperformancehouses.co.nz/assets/process-tab_images/INTperspective1.jpg

What about flat concrete floor where no underfloor insulation is possible.

For those of you who have ripped down gib and redid them what was the cost of doing so for a 3 or 4 bedroom typical NZ home? I know this isn't the requirement for existing homes and even rentals for that matter wall insulation isn't needed. There are new suburbs and streets with newer homes where they are more insulated per the building code but there are existing older suburbs like Mt Victoria in Wellington where many houses are over 100yrs old - you know some are inches away from the next door neighbour ;), some are yellow stickered (earthquake) but others are still OK. Thing is the land value there is quite high but the building itself might only be worth $100k, to some owners retrofitting insulation and double glazing windows might not be that beneficial right?

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#1984130 27-Mar-2018 10:43

For new builds, the concrete slabs have big polystyrene blocks placed before pour and these sit with/under the mesh.

You can also choose to underfloor heat (pipework).

wellygary

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#1984135 27-Mar-2018 10:46

You can still build a "raked ceiling" or cathedral roof, you just need to insulate between the outer and inner linings, - there are low profile products for that ie

https://pinkbatts.co.nz/product-range/pink-batts-skillion-roof/

Also you can insulate a new concrete slab, you install poly below and around the pour,

As for the economics of insulating old homes, in many places these are rentals, and new laws will require that they have ceiling and under floor insulation ( if practicable)

mdf

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#1984142 27-Mar-2018 10:54

That's a skillion roof. You just insulate it like you would a wall. You can get special higher density insulation, or use PIR boards.

We relined and insulated two bedrooms and a hallway for about $25K if memory serves; this was a few years ago though so memory may well not serve and there will be some inflation to take account of. We also did a few other things like adding a built in wardrobe at the same time so that may further muddy the waters. The wall linings weren't in a great state in places so it totally made sense to re-insulate while re-lining (we also did some additional cabling while the gib was off).

Depending on your cladding and the state of your current linings, @wheelbarrow1 found a pretty interesting retrofit product and describes his experiences over in this thread.

Note that you need building consent in most places to insulate external walls.

nickb800

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#1984157 27-Mar-2018 11:30

For a skillion roof like yours, there are three ways to retrofit (i'll ignore blown in insulation)

1) Remove roof cladding, add insulation, new wrap (building paper) and replace roof cladding (makes sense if your roof is shot)

2) Remove GIB, add insulation, put up new gib

3) Create that bridges between your exposed beams, fill with insulation, and install new GIB flush with the bottom of your rafter beams (good if you don't like the exposed beam look).

In 1 & 2, you need to ensure there is sufficient gap between insulation and building wrap to support ventilation and prevent moisture transferring into the insulation.

Concrete floors can be insulated with polystyrene pods underneath and/or on the perimeter edges. Neither is required for new builds unless your floor is heated. As hot air rises, ceiling insulation is the most important

The typical home is unlikely to be yellow stickered (earthquake prone) as almost always built with timber structure. However some brick/concrete elements (parapets, chimneys) may be earthquake prone - remove/fix these elements and your building is fine.

Materials wise you would be looking at $30-40 per m2 of wall area for retrofit (GIB, insulation, fixings, plaster, paint). Labour will be the killer. Also expect some upgrades to be triggered in the process - replacing that leaky pipe that you've just uncovered, replacing dodgy electrical wiring you never knew about, fixing that leaking wall, etc

You probably wouldn't recoup the investment straight away, especially if you sell shortly after. I'd be looking at what is happening to the neighbourhood - are houses being bowled for apartments townhouses - if so may as well run down your house and sell for land value. If people are looking after their older houses and reinvesting in them, then it's a different story.

rayonline

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#1984172 27-Mar-2018 11:52

You probably wouldn't recoup the investment straight away, especially if you sell shortly after. I'd be looking at what is happening to the neighbourhood - are houses being bowled for apartments townhouses - if so may as well run down your house and sell for land value. If people are looking after their older houses and reinvesting in them, then it's a different story.

Thanks all guys. Was curious to know. Doing to that skillion roof is quite a bit of work yeah .... We insulated underfloor and celing space where possible at the back ...

I know some some people who have the older 100yr old houses. Esp in the Mt Victoria city'ish area, definitely they others are being bowled over for apartment blocks or the few are bowled over for townhouses. Or like the many there are they quite old looking and simply kept that way. $100k what the building is worth defined by the Wellington City Council / QV. Renovation cost just not worth it ....

evilengineer

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#1984234 27-Mar-2018 12:24

A few points after reading the thread above

A house won't get red/yellow/green stickered until an actual earthquake has occurred and the building has been inspected for structural damage.
Earthquake prone building legislation specifically excludes single dwelling residential properties. Unless its been split into apartments a house can't legally be classified as EQ prone.
It's almost impossible for a single storey timber structure to kill someone during an earthquake. It's the high level masonry that will get you. If you've got an old house with a heavy chimney (particularly if it is unreinforced brickwork) it would be a VERY good idea to get it looked at and removed/remediated. Particularly in a high seismic area.
It is increasingly a good idea to insulate roof spaces and floor voids where possible. It will help with a future sale of the house and is becoming part of minimum rental standards.
Insulating external walls requires a building consent! It needs to be done properly to avoid moisture issues and isn't really a DIY job.
Similarly with skillion roofs, great care is needed to ensure that moisture can't get trapped leading to rot/mold issues down the track.

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rayonline

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#1984246 27-Mar-2018 12:44

Interesting you say that maybe diff to a commercial shop space or home rented out.

One is a small run down shop in a edge suburb someone I know has and it has been yellow stickered, they had the engineers do a report. The outside wall is a concrete wall, single floor and they said needed a post installed to strengthen the ceiling. Basically the work required ran up to the same value as the building it now is :-D but then the catch 22 is that the area is not prime land even if you build it new and sell it won't fetch a good price, I guess with the work put in they might get a 10% assuming it won't take too long to sell and paying interest to the bank etc. Think it has a 23% rating. Dunno what the confirmed rating is now, 23% is by council and basically got given 10 or 15yrs and then has to be demolished or work done.

Wheelbarrow01

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#1984302 27-Mar-2018 14:39

nickb800:

For a skillion roof like yours, there are three ways to retrofit (i'll ignore blown in insulation)

1) Remove roof cladding, add insulation, new wrap (building paper) and replace roof cladding (makes sense if your roof is shot)

2) Remove GIB, add insulation, put up new gib

3) Create that bridges between your exposed beams, fill with insulation, and install new GIB flush with the bottom of your rafter beams (good if you don't like the exposed beam look).

In 1 & 2, you need to ensure there is sufficient gap between insulation and building wrap to support ventilation and prevent moisture transferring into the insulation.

I have a 1960's brick veneer house which I bought almost 3 years ago. It had a cathedral/skillion ceiling with exposed rafters in the lounge/dining/kitchen area at the front of the house which did not appear to be insulated at all, however it had well insulated standard ceilings in the rest of the house. The first winter in this house was unbearably cold (Christchurch) so in October 2016 I basically did option 3 above - nailed up 4x2 'battens' between the rafters, installed R3.6 batts, then installed new GIB attached to the rafters/battens - all myself. I then paid someone else to plaster the GIB and paint as I wanted a quality finish. Total cost was around $3000 for materials and labour (ceiling area of approx 50m2). This made an immediate difference to the warmth of the house, along with a new ULEB log burner.

However after this work was done, the house was easier to heat but I still had problems with the house retaining heat although not nearly as bad as before. The log burner kept the house toasty warm while it was running, but even with full insulation in all ceiling spaces, it still lost heat reasonably quickly once the fire died down, and despite the improvements, the house was still pretty cold in the mornings.

Then in October 2017 I spent just under $5000 having Insulmax loose dry insulation blown in the walls. This is achieved by drilling many 20mm holes in the mortar joints on the outside of the house and blowing the dry insulation into the wall cavities under slight pressure, and then mortaring up the holes. I have previously discussed the full process for retrofit wall insulation as well as discussing some common myths here.

The difference in temperature and comfort in my house since installing the wall insulation has been truly remarkable - more so than the ceiling topup project that preceded it. While increasing ceiling insulation to 100% coverage helped achieve the desired temperatures with heating, the retrofit wall insulation has enabled the house to retain that heat far better and for far longer than with ceiling insulation alone. At the start of the process I wasn't entirely convinced I would see much benefit with the wall insulation, but I took the gamble anyway and the results far exceeded my expectations.

Sorry to hijack the thread, but I am a bit of a convert now in regards to retrofitting wall insulation, and I believe it should form part of anyone's plans to improve the comfort of older homes where it is practical to do so.

Aredwood

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#1984589 27-Mar-2018 23:35

rayonline:

Thanks all guys. Was curious to know. Doing to that skillion roof is quite a bit of work yeah .... We insulated underfloor and celing space where possible at the back ...

I know some some people who have the older 100yr old houses. Esp in the Mt Victoria city'ish area, definitely they others are being bowled over for apartment blocks or the few are bowled over for townhouses. Or like the many there are they quite old looking and simply kept that way. $100k what the building is worth defined by the Wellington City Council / QV. Renovation cost just not worth it ....

Don't take any notice of the "value of improvements" (house value) on your rating valuation notices. As that value is calculated by capital value, minus land value. This means that properties with higher value land value will have lower "values of improvements".

Imagine 2 houses that are exactly the same, except that 1 of them sits on a section that is large enough to subdivide. Not surprisingly, a section that is big enough to subdivide is worth more than 1 that isn't. That higher land value in turn translates to lower improvements value.

Work out how much it would cost you to rebuild on the same section. Keep in mind that (in Auckland at least, don't know about Wellington). There are lots of 100+ year old houses that don't comply with current planning rules. (as the house is older than the rules). This means that if you demolish and rebuild, you might not be allowed to build a new house that is the same size as your old house. Or might not get as much sun, have as good a view etc as the old house. You will almost certainly find that it would cost you far more than 100K to rebuild.

Demolishing and rebuilding will probably only make sense, If it will allow you to subdivide. My house also has a $100K improvements value. But could I rebuild an even basic spec 180m2 house in Auckland for $100K? No way.

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#1984597 28-Mar-2018 00:02

Aredwood:

Work out how much it would cost you to rebuild on the same section. Keep in mind that (in Auckland at least, don't know about Wellington). There are lots of 100+ year old houses that don't comply with current planning rules. (as the house is older than the rules). This means that if you demolish and rebuild, you might not be allowed to build a new house that is the same size as your old house. Or might not get as much sun, have as good a view etc as the old house. You will almost certainly find that it would cost you far more than 100K to rebuild.

Things like council setbacks and recession plans, also may not allow you to build as close to the boundary on a new house, as an old house, depending on when changes were made to the plan. I recall seeing a 'Grand Design' overseas, think it was Oz, where the owner wrongly thought that if they just retained one old wall from the old house, and build a new house around it, that it would be treated as a renovation to the old house, and they wouldn't even need a consent. But it didn't work, which is common sense.

rayonline

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#1984660 28-Mar-2018 08:43

Yes they had a few architects over. They rules now can't build the same land size as before. Unless it's a direct copy of the previous house just newer. That's why maybe the area just become apartments or left alone.

Subdivide no way. Mount Victoria are tight space housing. Apartments only way or townhouses. These places don't even have a garden. Nor garage. Or build new and sell it and earn that 15%. They didn't ask houses obviously but architects said 3 levels of apartments. 1.5 million build cost.

Had a dug thru. Yeah one of them advice was the council allows up to 75% of the land to be built so that is 171m squared. At the moment you probably guessed it the house parks right up to the boundary of the land. One one side there is no fence. Its the side of the building. This $1.5M cost to build 3 floors was dated 2013 so could be higher now. Some of the houses there you could ask your your neighbour borrow sugar or milk by just placing your arm out the window.

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JayADee

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#1984814 28-Mar-2018 11:17

Slightly off topic does anyone know in what year consent started to be required to retrofit insulation to external walls?

mdf

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#1984864 28-Mar-2018 12:29

JayADee: Slightly off topic does anyone know in what year consent started to be required to retrofit insulation to external walls?

Looks like late 2010. The current exemption (exemption 13, you do not need building consent to install insulation unless it's an external wall or firewall) was made then. While its an exemption, I suspect in practice people didn't consider retrofitting insulation before then to be building work. That's certainly the tenor of the official guidance in that link.

rayonline

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#1984867 28-Mar-2018 12:33

I know a friend who moved here less than a year ago bought a house built around 2000 newish u can say. So insulation might not be then... Hmmm.

JayADee

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#1985041 28-Mar-2018 16:17

mdf:
JayADee: Slightly off topic does anyone know in what year consent started to be required to retrofit insulation to external walls?

Looks like late 2010. The current exemption (exemption 13, you do not need building consent to install insulation unless it's an external wall or firewall) was made then. While its an exemption, I suspect in practice people didn't consider retrofitting insulation before then to be building work. That's certainly the tenor of the official guidance in that link.

Thanks, we did it in 2002 and I thought remember it didn't require it then.
Rayonline, I think houses have required insulation of some kind since the late 70s?

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