LEAKY HOMES & REASONS

[minimoke]

The house that he was working on a few months ago had actually won the Master Builders Home of The Year two years ago. It still leaked.

There must be some mistake? Dunc started this thread in 2005 - and leaky homes had been around before then. The master builders home was probably built in the last four years - hopefully the tax payer isn't stumping up to repair this one!

[airedale]

That is the point, Minimoke, "leaky homes" have been around since building standards were changed for the worse, and they are still being built.

[ari]

Finally someone is talking sense........

quoteesign, not the timber, leads to leaky buildings, says expert
19.07.05
By Arnold Pickmere

Poor design, not untreated timber, is the leading cause of leaky buildings, says a Canadian expert.

Dr John Straube told an Auckland University symposium yesterday that the biggest problem was modern designs which exposed building seams to wind and rain - simple things such as not having eaves or proper flashings on windows, flat roofs and enclosed decks.

Better design of wall systems would ensure that water which got in could also get out.

Dr Straube, who has a joint role with the University of Waterloo's civil engineering department and school of architecture in Ontario, said using untreated timber in a modern building in which moisture and rain were not controlled was like using a canary in a coalmine.

"You put some untreated timber in a building, so you found out [about leaks] sooner," he said.

Moisture problems in buildings had occurred in various countries with both wood and steel framing.

Untreated timber was also used in many countries. But the qualities of such timbers varied. Dr Straube thought the best of untreated New Zealand pinus radiata was equal to the worst of Canadian timbers.

But when the timber was treated to H1.2 [full sapwood penetration timber] it was better than the best of untreated Canadian timber.

But the essential thrust of Dr Straube's lecture was that buildings leak. Even a glass-clad building may eventually leak round the sealants.

He said there were buildings hundreds of years old which had been designed to cope with the present problems. "It's not new technology and its not rocket science."

Professor Geoff Duffy, of the Auckland University's faculty of engineering, said: "Wood is hygroscopic as well as bio-active, so we must keep water away from it or remove it when it does invade."

Greg O'Sullivan, of buildings surveyor Prendos, said comparing untreated pinus radiata with, say, douglas fir in Vancouver was not comparing like-products.

The douglas fir was much slower-growing and had a lot of natural turpentine, which increased its resistance to insects.

Mr O'Sullivan said the biggest problem New Zealand faced was to educate designers and builders.

[dinosaur]

Sorry Ari, I might be sounding like the little boy in the story, The emperor has no clothes!
What if the system they want to educate us on is wrong?

Do you need to be an academic to know the problem, and is a academic "an expert"?

Building seams have been exposed to wind and rain for hundreds of years, in buildings built of untreated timber. I do agree about his comment on NZ Radiata Pine, as I have always believed our best wood is exported. Our pine now seems to have a very open cell structure because it has grown so quickly, hence it will take up moisture if exposed to it.

Take your average 100 year old victorian villa. Small to no eaves, large exposed faces, very exposed seams as in boxed corners, especially in two storied gabled villas, no back flashings, no silicone, no building paper and no rotting and built of untreated kauri which will rot quite quickly when exposed, especially prone dry rot. OK, they are as cold as heck in winter.

The reason for not rotting seems to be the top to bottom wall cavity ventilation, although I have recently been involved in a villa restoration and although the weather boards were only 12mm thick with as little as a 20-25mm lap and no weather grooves there was no sign of water staining which is associated with periodic water penetration and no rot. It did have borer though.
This villa was on a very exposed hill in the country. Looking from inside out through the weatherboards there was plenty of daylight showing hence you would expect that driven rain would have come in.

This breaks all the new rules yet it has stood the test of time for over 100 years????? Maybe it due to pressure equalisation, that is if the pressure behind the cladding is equal to that on the outside, water is not drawn in, even if there are gaps.

The new cavities E2/AS1 (the new acceptable solution for external claddings) calls for are NOT ventilated cavities, but in fact drainage cavities as there is no requirement to have vents at the top of the cavity, like in brick veneer constuction, only at the bottom, which will be prone to being blocked by insects, especially mason bees and wasps.

Having seen the verification method they are using to test claddings, my first reaction was that it didn't represent a real situation with unequal pressures on each side of the wall system that you get in a house, infact there was no internal lining and the test wall was open at the top to the back.

[duncan macgregor]

DINOSAUR, It is all very simple to understand really. All this treated timber, or untreated timber, or bad builders has very little to do with the problem. The problem lies solely with the people that make the rules. The rules up to the seventies never encountered the leaky home problems that we have today. They had bad builders idiot designers, untreated wood, so lets concentrate on what changed. The spanish look was born, thats when the rules changed. We had air tight walls full of insulation like it was the artic circle. That in its self is a great mistake the pressure inside the wall is less than the pressure outside the wall, so that the wall will suck water up hill like drinking with a straw. They still dont know that, that is the problem they run round like headless chooks each blaming the other.If you want a ROLLSROYCE job dont try and do it with LADA parts. If you want a Spanish house build it with blocks the way the Spaniards do not like these clowns on a timber frame. macdunk
PS brick or weatherbrds or nothing

[ari]

quote:PS brick or weatherbrds or nothing

I have moved from a brick house of 16yrs old into new 'chilly bin' house. This new house (with gas fire) has no condensation what ever as the aluminium joinery allows the rooms to breath. Whereas the brick house had the earlier joinery and condensation was such a problem that the varnished window sills had started to rot.
The new building system, whether it be weather boards or insulclad has a far superior system as a secondary barrier than anything before.
If certain persons on this site took the time instead of jumping on the wagon along with everyone else to familiarise themselves with systems such as Themocraft coverup and Protecta sill systems we might just have an informed debate.

[duncan macgregor]

ARI, Good luck with the new house, but it is you that has a lot to learn. Windows that can breathe are great . Your cavity system on your chilly bin house leaves a lot to be desired. It stops the suction problem but it falls over very badly later on as you will find. Lift a bottom plate up and look at the state damp course gets in after a few years. Remove the outside cladding and see what happened to the building paper. Fix lots of jobs up like i have done then you wont be so smug about living in a chilly bin. macdunk

[ari]

Yes I agree there have been major probs with earlier 'chilly bin' houses. I assisted on repair of one 3 years ago and I tried to get owners to reclad as the probs are still onging. My bro built with monotek system and his probs are just starting so I certaintly did not go into this lightly.Time will prove whether paper rots just like the black paper did on the brick house.
What I am saying is that if people took the time to avail themselves of info available (it's not rocket science as someone said) and not keep saying it never happened 100 years ago!
The sealing system around doors and windows is certainly superior to anything (none) available in the past. As is the requirement to champher doors/ window bottom plates to outside for drainage.

[duncan macgregor]

ARI, The sealing system round windows and doors creates a great problem. In the old days there was a gap between the window liner, and the frame, other than wedges with a scriber on the outside. Today under the latest rules we have a 10 mm gap between the liner and the frame that gets filled with gap filler, which creates a suction in its self, plus a capillary reaction. The people making the rules never went to night school like we old timers did, and know nothing about the science side of building. The mastic sealers have a short life read what it says on the tube sometime. macdunk

[ari]

Duncan...I give up, you win.
Pity you did not put your name forward for the Auckland Uni Symposium to expound your views.
Good luck with your crusade.