How to insulate 1950/1960-x weatherboard walls?

[ivanp]

Hi

One of my properties is a 1960x house with timber weatherboards and no insulation in the walls.
There's no building paper or cavity. Weatherboards are directly fixed to structure.
Weatherboards have splaycut profile, i.e. internal surface of cladding is very flat, without gaps (that are present with bevel-back weatherboards).

Looking at other 1950-60x houses on open homes I notice that most of them don't have any building paper too...

Question: if some day I decide to remove lining and insulate the walls in such a house - what is the proper way to do it when there's no building paper and no cavity?

Installing building paper from the inside doesn't look like a safe option as it will be hard to keep air gaps behind weatherboards, so moisture will be trapped here...

It seems like insulation from outside is the only safe option, but it's very expensive (remove old cladding, install building paper or something rigid, install cavity battens and install new cladding)

Thanks
Ivan

[Viking]

Why worry unless you live in a cold area?
Most heat goes out the ceiling and the windows. double glaze and ceilings and if you have to the floor.

[jimO]

the correct way is either remove outside cladding or inside cladding, if doing inside you fit the building paper in each gap between studs staple it to the studs making sure its not against the weather boards, I dont think you need to form a cavity on a existing house if recladding but not sure. you can get sprayed in products that is installed by drilling between studs and its pumped in but would pay to check with your local gestapo whats recommended. you also need a consent to fit insulation however i am currently doing one of my properties room by room from the inside and havnt bothered getting one as i firmly believe the council gets enough money out of me already

[Ahar]

I've heard that the sprayed in foam has caused huge problems....at least that's the experience overseas where they've been using this method for some years

The foam leaves no air gap and hence no ventilation to dry the timber if any moisture gets in.....the result has been to create a new class of "leaky homes"

[jimO]

I've heard that the sprayed in foam has caused huge problems....at least that's the experience overseas where they've been using this method for some years

The foam leaves no air gap and hence no ventilation to dry the timber if any moisture gets in.....the result has been to create a new class of "leaky homes"

yes thats why i suggested checking with the council, certainly filling the cavity up doesnt seem like a good idea

[drelly]

Yeah don't do it. You lose ventilation in the walls. Just get a good log fire and they're warm as toast.

[wormdoggy]

Hello

This is my first post so I thought it only fitting to chose a topic of my expertise. I've been in the insulation business for well over 20 years and a home builder for over 10 years.

I don't particularly know the products available in New Zealand at this point but the application would be quite similar to most countries. Certainly the construction of your home is the big question?Removal of the interior drywall or cladding would be your best option. Spray foam insulation would an option either in 1/2 pound or 2 pound spray. It would provide the best seal against studs and cavities and the poundage would be based on the R value you are trying to achieve. It would work if there is an outside sheathing to the home? Certainly not recommended with applications against paper or exterior cladding. In addition no vapor barrier would be required for 2 pound foam.

Roxul or mineral fibre another great choice in order to provide sufficient R value and high temperature burn rate in the event of a fire. Some insurance companies will drop your rates considerably if this product is used. You can do it yourself quite easily similar to fiber glass batts. Its a natural product used extensively in North America for insulating/fire barrier and acoustical ( noise dampening).

Fiber glass is the most common used. The R value will depend on climatic conditions of your area and the building codes.

Mold caused by water accumulation is your biggest concern. Keep in mind that water damage or condensation is caused by cold air meeting hot humid air and inadequate air circulation or venting. A vapor barrier glued and stapled to the studs after the insulation is installed will act as a membrane/ vapor barrier. Sealing all cavities with tape and silicone is extremely important since a pin hole is equivalent to a glass of water per year. I cannot stress the importance of sealing the vapor barrier properly to avoid condensation. These methods are proven around the world and used in North America to prevent " leaky homes". But again one should check with the building code.

One of the concerns I've seen during my visits to New Zealand is the lack of proper venting either behind exterior cladding or soffit venting into attic spaces. The long term deteriorating effects and health issues are problematic if water condensation is not addressed properly within a home.

I live in Canada and will be migrating to New Zealand in 2017 and I have been actively involved in the construction business for many years. I just recently sold my business in anticipation of the migration and look forward to continuing in this field. I am currently designing my new home to be built in New Zealand.

I hope I have helped and look forward to additional posts.

Thank you
Patrick

[John the builder]

Patrick
in NZ we don't use vapour barriers as such as we only get the freezing effect of extreme cold in alpine and certain areas.

You need to read up on NZ approach ad understand why we do this. Having said that we now seal up our buildings to such an extent that perhaps vapour barriers should be introduced.

JimO

i am currently doing one of my properties room by room from the inside and havnt bothered getting one as i firmly believe the council gets enough money out of me already

council didnt make the rules on when a consent is required the govt did. The reason that wall insulation requires consent is to stop the foam pumping boys who tell everyone that their system is exempt on pre-1992 houses which is rubbish. They should have allowed manual placement methods. It is silly you can remove the lining and replace without consent and not put some insulation in at the same time without consent.


when working on an existing dwelling code compliance of the building is not the requirement but we should improve cpompliance.

Insulating with polystyrene sheet carefully cut to the studs as a good option as you can keep the insulation clear of the exterior cladding.

[wormdoggy]

Patrick
in NZ we don't use vapour barriers as such as we only get the freezing effect of extreme cold in alpine and certain areas.

You need to read up on NZ approach ad understand why we do this. Having said that we now seal up our buildings to such an extent that perhaps vapour barriers should be introduced.

JimO

council didnt make the rules on when a consent is required the govt did. The reason that wall insulation requires consent is to stop the foam pumping boys who tell everyone that their system is exempt on pre-1992 houses which is rubbish. They should have allowed manual placement methods. It is silly you can remove the lining and replace without consent and not put some insulation in at the same time without consent.


when working on an existing dwelling code compliance of the building is not the requirement but we should improve cpompliance.

Insulating with polystyrene sheet carefully cut to the studs as a good option as you can keep the insulation clear of the exterior cladding.

Hello John

As I mentioned in my email the building code for your area will dictate the conditions of vapor barriers and their usage,however, the debate over vapor barriers and usage is probably just as old as the big bank theory and the creation of the Universe.

You are right that our Canadian weather is quite different in the winter months but that only accounts for 6 months ( if were lucky ) and the remaining 6 months quite similar to New Zealand weather in varied locations.

Accordingly, if the application of vapor barrier and usage were to be used in Canada similar to New Zealand standards then in theory it should only be acceptable and applicable for our winter months where the humid air within the house is greater then the dry air outside? But how about the summer months? We still have the vapor barrier installed within our homes?

As mentioned in my earlier email, the house construction and "venting" would be the main driver for use of barriers or retarders. It all comes down to pressure and leakage within the home and wether the homes is experiencing exfiltration ( air leaking to the outside of the house ) or inflitration ( air leaking within the house ). In all cases it comes down to the mechanical systems, wind and stack effects. In all my years of building homes, I have yet to see any water damage or condensation with the walls where vapor barriers were installed, in hot summer humid months or cold winter months, but our codes for mechanical systems and venting could be different then New Zealand. I don't know at this point.

Indeed the only areas where I have seen considerable water damage is insulation on concrete or block walls. In all cases Fiber glass insulation was used with improper seals and the wicking effect occurs within the house since the pressure is greater below grade. In addition these areas were not vented properly.

Patrick

[John the builder]

NZ has a national building code.

we dont have requirements for mechanical venting (unless its wc/bathrooms etc without windows) and rely on opening windows which in itself causes issues especially in rented dwellings where tenants seem averse to this or simply ignorant of the need to open them up.

[wormdoggy]

NZ has a national building code.

we dont have requirements for mechanical venting (unless its wc/bathrooms etc without windows) and rely on opening windows which in itself causes issues especially in rented dwellings where tenants seem averse to this or simply ignorant of the need to open them up.

Indeed you are very correct John
Opening windows to allow humidity into a house can be extremely problematic.
Drywall or gypsum in itself is a vapor barrier that prevents water diffusion. I read a book once upon a time about air leakage and water diffusion through drywall or gypsum. Scientific testing performed.
Over an entire season water accumulation was typically 1/3 cup per 1 sheet of drywall or gypsum board , however, and this is the key, if we were to puncture a hole through the gypsum/drywall 6cm, the water accumulation would increase to and incredible 28 litres.

Patrick

[Nesian]

Don't mean to hijack the thread but I'm renovating a 1950's bathroom so there is no building paper on the external facing wall. Seeing as I have all the wall linings down I thought it would be a good opportunity to insulate with batts but if I do this it means I need to get a consent which means spending more money. We are just updating the house before we sell it. Would you give the insulation a miss to save getting a consent or should I insulate and get a consent? Thanks

[jimO]

Don't mean to hijack the thread but I'm renovating a 1950's bathroom so there is no building paper on the external facing wall. Seeing as I have all the wall linings down I thought it would be a good opportunity to insulate with batts but if I do this it means I need to get a consent which means spending more money. We are just updating the house before we sell it. Would you give the insulation a miss to save getting a consent or should I insulate and get a consent? Thanks

make sure you building paper it properly from the inside and bung some batts in

[Wayne]

I'm with jimO on that one.
Just do it in a workman like manner and who would know after the linings are back on?

[John the builder]

you could tell the council what you are doing and ask for an exemption from consent under schedule 1 (2) of the Building act.

A sensible council officer would tell you to get on with it but if Auckland then sensible and building officer may be an oxymoron.