why it all went wrong in the building trade.

In the good old days we all served apprenticeships from practical builders who understood the laws of the trade.
The first law being, that all timber should be kept dry and be allowed to breathe, with a natural ventilation system.
the second law was all roof pitches be steep enough to combat capillary reaction that sucks water up hill.
the third and most important law being that all external walls should be able to breathe to equalize external pressure with internal pressure otherwise the wall will suck water even uphill which no builder can gaurd against.
The only homes that complied in the last thirty years were either brick veneer or weather board homes up to just recently when they introduced cavity external walls on spanish plaster immitation homes over wooden frames.
In the days of very few rules with houses being built by practical tradesmen who understood natures rules there were very few problems.
In todays world we have councils bleeding the life out of the building trade, with people making rules and regulations about things they know nothing about.
I used to marvel at the stupidity at the master builder feferation awards each year when the awards went to what I considered was a high risk potential building disaster.
Where was the master builders federation when they introduced leaky homes to the unsuspecting public?. I know several of my builder friends all held their hands up in horror when that happened. We now have over the top regulation with rules made up by people with no understanding of natures natural laws. This now is placing homes beyond the reach of the average person who simply cant afford to buy. I used to be able to talk to the building inspector about how to over come a minor problem, then come up with a solution, today I have to pay for an engineers report, and wait on approval from the man that knows nothing about anything. Macdunk

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Originally Posted by duncan macgregor

the second law was all roof pitches be steep enough to combat capillary reaction that sucks water up hill.

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Quote:

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Originally Posted by duncan macgregor

the third and most important law being that all external walls should be able to breathe to equalize external pressure with internal pressure otherwise the wall will suck water even uphill which no builder can gaurd against.

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Just out of interest can you please elaborate on these points?

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Originally Posted by Lego_Man

Just out of interest can you please elaborate on these points?

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1, The air preasure in the attic is less than the external air pressure on the external wind side on the exterior. This creates a suction which will cause to low a pitch to suck water up into the roof. On that note if you stack normal roof iron outside on the flat it will develop white spots in a few weeks, and will be rendered useless by electtrolysis. Old roofs rust out quicker by electtrolysis than by rust. Painting a roof is less important than painting the laps between the iron.
2. External walls require ventilation.
If you build a timber frame and cover it inside and out like a thermos flask in a similar way to the immitation spanish plaster homes of the recent past this is what happens.
1, The pressure inside the wall tries to equalize with the pressure on the wind side of the wall. During great gales the difference is considerable. This in turn will force every pin hole in the wall to suck in water even uphill. This might only happen when the wind and rain comes from an odd direction. The modern method of sealing the bad spots is a sealant with a gaurantee of about only little more than ten years on a house expected to last a life time.
Weather boards are not air tight neither is brick veneer so no problem.
The home buyer should never buy an immitation spanish plaster house unless it has an external wall cavity that eliminates that problem. Macdunk

Great post.

Thanks again McDunk.

I am not sure all builders understand this as well as you do, Duncan (and it takes REAL understanding to be able to explain). Thumbs up.
The change from relying on each individual builder getting every little thing right, to the important things having to be on someone's checklist that have to checked off, is partly a response to the fact that as technology advances there are more complicated options and details out there. People keep coming up with new building materials or systems (whether from Italy, China or Germany, or local) and we need this not to become like cowboys flogging off snake oil as construction adhesive that can also be used as paint AND to plasticise cement...and it's low VOC so you can drink it!
Sure we end up with belts and braces just in case you don't wear underwear (and therefore need 99.9% confidence that your pants won't fall down) but there is continual improvement (eg. a checklist that if you have underwear you can dispense with the braces, but not if you are going out in a howling gale in the antarctic (but yes if it's summer), and you can apply to have no underwear or braces by submitting the test results of your special steel belt or your special lycra bike pants.)

ps. I do not work for the council, Duncan, I just think you are being a little harsh when you say "councils bleeding the life out of the building trade, with people making rules and regulations about things they know nothing about." Mostly it is knowledgeable experts (BRANZ, master builders and architects submitting to panels) with a dash of politices. There had to be a substantive change... we couldn't keep going the way we were.

You do raise a good question that I need to think further about - the idea than we need a way to produce an uncomplicated house at an affordable price.
(I am aware that there is a new scheme where the likes of fletcher homes can get a general design approved that accomodates re-using for many homes. It only goes part way as every house needs a site plan, with drainage connections and sun orientation etc. And this does nothing for one-off houses.)
And the other way to create affordable housing is to use less land ( by building apartment buildings. Typically these larger constructions will be unique designs, but here, too there is possiblity for re-using standard details and still not building identical buildings. [Rows of apartment blocks in Russia or 1960s Britain do not seem attractive, but I was quite happy with the repetitive 'Nelson blocks' and prefabs at school when I was growing up.]

ToBo
(I am an architect doing commercials buildings, but this post is not to be taken as architects advice or financial advice. Just a rant. DYOR)

Quote:

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Originally Posted by duncan macgregor

In the good old days we all served apprenticeships from practical builders who understood the laws of the trade.
The first law being, that all timber should be kept dry and be allowed to breathe, with a natural ventilation system.
the second law was all roof pitches be steep enough to combat capillary reaction that sucks water up hill.
the third and most important law being that all external walls should be able to breathe to equalize external pressure with internal pressure otherwise the wall will suck water even uphill which no builder can gaurd against.
The only homes that complied in the last thirty years were either brick veneer or weather board homes up to just recently when they introduced cavity external walls on spanish plaster immitation homes over wooden frames.
In the days of very few rules with houses being built by practical tradesmen who understood natures rules there were very few problems.
In todays world we have councils bleeding the life out of the building trade, with people making rules and regulations about things they know nothing about.
I used to marvel at the stupidity at the master builder feferation awards each year when the awards went to what I considered was a high risk potential building disaster.
Where was the master builders federation when they introduced leaky homes to the unsuspecting public?. I know several of my builder friends all held their hands up in horror when that happened. We now have over the top regulation with rules made up by people with no understanding of natures natural laws. This now is placing homes beyond the reach of the average person who simply cant afford to buy. I used to be able to talk to the building inspector about how to over come a minor problem, then come up with a solution, today I have to pay for an engineers report, and wait on approval from the man that knows nothing about anything. Macdunk

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Spot on MCDUNK,

the same applies to the plumbing game, you went to the Drainage board and the inspector pulled out the drainage plans and you discussed what was required for an addition or whatever. Any problems and you sorted it amongst the two of you, the inspectors usually were ex plumbers or drainlayers.
Alot of these problems arose when things changed, now most of these guys would,nt know s!!!t from clay.
Today any mug can buy a made flashing and gunk it down, most would/nt know how to flash a chimney or knock up a flashing let alone use a soldering iron.
And your right 'gunk' is only good for a short while---look at all the leaks ,spouting flashing etc.

Tobo, Good post, but being an architect the first thing you would have learned that air pressure must be equalized in exterior walls. The wall must be able to adjust internal pressure with fluctuating external pressure otherwise a suction is created where water gets sucked up hill. No builder can build against that when it happens, and the blame placed entirely upon the designer, and the people stupid enough not to foresee the problem. The master builders assc have endorsed this type of design by awarding leaky home buildings in their home of the year awards for numerous years, right back to the late seventies. I argued with countless inspectors for years, long before leaky homes was a problem. I was told not to be so stuborn, or stupid and get on with it. What has happened now that they have woke up is, they have gone into an overkill mode resulting in enormous unnecessary expence to the home buyer. The building game is managed by straight out incompetents in NZ resulting in the homes in this country are over priced compared to most countries due to ignorance and down right stupidity. Macdunk

Hey, Duncan, I agree with you on that...Might have sounded as if i think it's all okay because, having to deal with the increased bureacracy and overdetailing on day-to-day basis, we try to tell ourselves 'just get on with it and don't moan'.
But we still have our "you won't believe what the council just asked for!" outbursts.

(And, although we learned about pressure equaisation, we also have an arsenal of other systems (eg. basement/lift pit tanking), some of which are still the subject of debate. One current debate is the idea that blockwork should not be used as an exterior surface as it is even more porous and absorbant than concrete, and relies on paint (a membrane paint) to be waterproof.
Tobo

Ron, something that has been circulating among architects is the idea that when you design weatherproofing details, the flashing should completely work without any sealant. Ie. you assume there is no sealant.
(This relates to external sealants, since another role is sealing the inside side of the drained cavity idea, although here too there can be some failure allowing air leakage through the internal side, and the whole cavity system still works)