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duncan macgregor
18-02-2008, 08:23 AM
My next door neighbour over the back has a small acreage divided into two paddocks fully fenced off, with an existing private road up to their house in the back paddock. They wanted to split the property up to allow their daughter to build in the front paddock. The daughter had to come to me, and the surrounding neighbours first of all to get our approval.
The property has its own water supply, and would be on a septic tank system at no expence to the council. It cost them $56,000 in fees, and other bullsh*t before they were allowed to even start building. They then had the added expence of insulation, and double glazing as if it was being built in the artic circle. Its all this namby pamby crap that will drive the young people off overseas to greener pastures, and cheaper houses.
In the bad old days before leaky homes existed, we used to drill holes in the bottom plate to allow the walls to breathe which equalized the pressure to stop the wall sucking water in and up. Today we fill the wall up with insulation like a thermos flask then try and find the leak. Macdunk

Serpie
18-02-2008, 08:42 AM
So each cavity that you built was a vacuum, and needed a hole drill to equalise the pressure? Come on Macca - really?

You can't argue about the value of insulation (well - I suppose you can if you want). I lined the underside of my weatherboard house in CosyFloor last winter (pink batts with a foil backing) and what a difference!
I was watching a Canadian programme about house construction, and they were talking about using batts with an R24 rating. I thought that they must use a different rating system, until I saw the batts. It was about 18 inches thick. That's what you ned for the Arctic circle.

Double glazing should be optional though, and the "reserve" and "water" contributions that local councils charge are extortion, especially when there's no park within 5km, and you sink your own well.

duncan macgregor
18-02-2008, 09:22 AM
SERPIE, If i fly on an aircraft i expect the designer and manufacturer to have a basic understanding of the principals of flight. The building trade is cotrolled by people with no basic understanding of the laws of capillary action, or air pressure in walls or roofs. Water gets sucked up hill under certain conditions.
Leaky homes started with an airtight plastered wall on a timber frame. The air pressure outside the wall is greater than the air pressure inside the wall. There is no builders myself included that can build a house that wont leak under those conditions. I refused to build that type of house, and argued the point all the way with inspectors since the mid seventies. The air pressure inside your roof cavity is lower than the air pressure on the outside thats why you cant have really low pitch roofs. Place two sheets of corrigated iron on the flat one on top of the other and notice the water inbetween even on a hot day.
If you leave the two sheets of iron you will notice large white spots that you can poke out with your finger. Look at sheets of roofing iron in the store next time, ever wondered why it says stack dry. The ignorance in the building game by the people in control is costing you heaps. Macdunk

Serpie
18-02-2008, 09:52 AM
Some muppet put a lean-to on the back of my house (before I bought it) with a 3 degree slope corrogated iron roof on it, so I've found out that water can indeed run up hill! It runs up hill until it hits the top plate, and then starts running down hill - until it reaches the carpet!!
I thought the leaky homes thing was mainly caused by internal gutters and reducing eave size, so I've learnt something today.
So I take it you don't have a lot of faith in BRANZ? I've never been to BRANZ to have a look (I've read their bulletins) but I imagine it would be quite interesting. Have you visited them?

Financially dependant
18-02-2008, 10:19 AM
Don't forget that a house is dynamic, temperatures, moisture levels, pressures are constantly changing in direction and level, seasonally, daily, climatically and place to place.

Drilling holes throughout a house to ventilate it may work in the Bay of Islands but not in Cromwell, there is no one 'fix all' approach.

tuff'n up does nothing for your health, that is builders logic that put the housing stock in the sh*t it is now, run by builders for builders.

Look at the Canadian building model is see how a house should be built in timber, that is where the smart people in the building industry are looking for help.

Disc. not Canadian!

Serpie
18-02-2008, 10:26 AM
I love watching "Holmes on Homes" on the Living Channel. Those Canadians know all about controlling moisture.

STRAT
18-02-2008, 10:52 AM
Hi Duncan/Serpie, I would suggest vacuum has nothing to do with leaky homes. Capillary action which is only one of many reasons for leaky buildings has nothing to do with vacuum or air pressure either.

Joe King
18-02-2008, 11:14 AM
Great post Dunk.
I have a builder mate in Seattle who was involved in the early days of "leaky home syndrome" in USA (5 years before problem in NZ). He took me to several problem houses that were under going "try to fixit" and I saw exactly what the problem was..... exactly as you describe. Admittedly they have a wider range of temperature extremes but the vacume effect you describe was definitely the problem.... A few years later he came to NZ, saw what was happening here and predicted correctly what was down the track... common sense really... he sure was right.
I was totally gutted to discover the lovely new home we had just built was in fact constructed with untreated timber, and clad in the Hardy cladding very popluar in 90's. Just 2 years after completion part of the coloursteel roof needed replacing, in the process the roofer stuck a nail through a cable which required removing a sheet of exterior cladding. Imagine my horror to see white fungus growths apperaing on the lower studs already. Needless to say we moved house. I recently spoke to the new owner who told me that although they had no MAJOR problems the whole house hade been treated with a fungicide applied through the plaster walls into the framing cavity.... Yerk! We made sure there was lots of ventilation throughout the framing space both top and bottom when we built our current home... Hinuera stone.
Cheers
JK

STRAT
18-02-2008, 11:26 AM
Hi Joe, At the risk of being labeled pedantic and sparking an endless debate there is no vacume or differential pressure in the wall space of a house.:eek:

ari
18-02-2008, 11:27 AM
Back to Dunk's original post which mentioned Council fees........a friend of ours has made enquires re the subdividing (really just wants to cut off a small corner of 50 acre farm). 15 acres has to be planted out in native plants as a first step!
Yet, around Taupo they allow 1000's of acres to be converted into dairy!

Serpie
18-02-2008, 11:33 AM
Strat,

Us sparkies go to great lengths to ensure that there are no cavities in new homes that do not get converted into something resembling swiss cheese. And we charge no extra for providing this ventilation service.
(Please remember your local sparky this Christmas - and give generously).

While you're all here - anyone know how to kill mould on timber? I've been chasing rot in old old house, and using a timber preservative to treat those areas that are sound, but that have had mould growing on them. Any ideas?

STRAT
18-02-2008, 11:46 AM
Strat,

Us sparkies go to great lengths to ensure that there are no cavities in new homes that do not get converted into something resembling swiss cheese. And we charge no extra for providing this ventilation service.
(Please remember your local sparky this Christmas - and give generously).

While you're all here - anyone know how to kill mould on timber? I've been chasing rot in old old house, and using a timber preservative to treat those areas that are sound, but that have had mould growing on them. Any ideas?Hi Serpie
Re great lengths, Perhaps you should be looking for that extra cash from the builders whos jobs you are doing.

Re mould, There are products available but I think most of em are based on bleach. Problem is it spreads by producing spores which is about as easy to control as the breeding habits of rabbits. There are anti mould paints available now too which are effective but expensive. The key is the moisture level in the timber. Where is the mould?

By the way mould, wet rot and dry rot are three different problems

duncan macgregor
18-02-2008, 12:01 PM
Hi Joe, At the risk of being labeled pedantic and sparking an endless debate there is no vacume or differential pressure in the wall space of a house.:eek: Sorry to say it STRAT but you are wrong. That is why they now insist in a cavity on that type of exterior wall. Weather boards, Brick veneer etc as they used in days gone by were not air tight creating this vacuum. To smother timber so that it cant breathe is asking for trouble. The air pressure inside your roof is less than the air pressure outside. With exterior walls if you dont equalize the preasure the water gets sucked in, even up hill. Until they understand that which was one of the very first things taught to me as an apprentice then its blame everyone and everything for this shambles. Macdunk

POSSUM THE CAT
18-02-2008, 12:20 PM
Serpie Try oil of cloves

Serpie
18-02-2008, 12:21 PM
Gees Dunc - you're starting to get into aerodynamics there! I was surprised at how much of a builders job is related to ensuring that the house doesn't fly away, rather than making sure it doesn't fall over. Wind pressures, and the pressure differentials created by it, are amazing things.

Strat,
I've got all 3! South side, behind the weatherboards. The rot isn't a problem, because it all gets replaced, but I want to ensure that the accompanying mould is nuked while the cladding is off.

Serpie
18-02-2008, 12:23 PM
Serpie Try oil of cloves

Is that like "eye of newt" - or are you serious Possum?

STRAT
18-02-2008, 12:25 PM
This post will probably have me labeled as pedantic forever but Im gonna go with it anyway.
One of the things my business does is to set up Pressure regimes in buildings such as pharmaceutical production plants etc.

To create a vacuum ( an air tight cavity, container or compartment ) the contents of the cavity must be removed ( void of any matter including air )

To create a pressure differential in something like a roof space without an almost airtight building structure and the assistance of fans is near impossible. 1 hole as small as a nail hole will cause the pressure to equalize. There are a few rare exceptions in windy conditions where velocity pressure or temporary atmospheric differential pressure could create these conditions but you probably should be more worried about the roof coming off rather than leaking :D

The action I believe you refer to is capillary action being something else again. See below as Im too lazy to write it myself:D

http://en.wikipedia.org/wiki/Capillarity

Serpie
18-02-2008, 12:41 PM
It would be the drawing up of moist air due to a pressure differential, rather than the drawing up of standing water due to capillary action wouldn't it?
(Loving this conversation. Fascinating stuff.)

STRAT
18-02-2008, 12:46 PM
It would be the drawing up of moist air due to a pressure differential, rather than the drawing up of standing water due to capillary action wouldn't it?
(Loving this conversation. Fascinating stuff.)Trust me on this there is no pressure differential in your house unless you spent the cost of 10 houses creating it ;) and if I had a buck for every time I have explained to a building contractor ( not being a smart **** here Duncan )that I cant create a pressure differential because of the smallest of holes I would be retired :D

STRAT
18-02-2008, 12:56 PM
Strat,
I've got all 3! South side, behind the weatherboards. The rot isn't a problem, because it all gets replaced, but I want to ensure that the accompanying mould is nuked while the cladding is off.Dunno mate, best ask a builder about that one;)

Phaedrus
18-02-2008, 12:59 PM
Serpie,
I'd recommend Metalex Green (Copper napthenate) as a good fungicide.

duncan macgregor
18-02-2008, 01:01 PM
Here we go again STRAT. Capillery action is the action of a liquid rising up against gravity the example being water in a glass climbing the sides or blotting paper where the water defies gravity rising up the paper. Pressure in a wall or roof cavity,is less than pressure on the outside of the building. The more air tight the wall the bigger the difference. Timber that is dry, and kept dry with ventilation, wont rot go mouldy or dissintregate with dry rot.
Timber that gets damp either with lack of ventilation or a leak or perhaps wet when installed goes mouldy, can develop into a very dangerous health risk.
To build a timber wall with no ventilation that has a wet or damp risk is asking for trouble.
They build a house stick an airtight exterior cladding that cant breathe like weatherboards for instance, then expect it not to leak. I argued that point with dopey building inspectors for years the bloody house will leak. The first downpipe that gets screwed to the wall is your first leak. The second leak is the gunk that cracks with old age at about five years old.round your widows.
The house sucks the water in simply because of the difference in air pressure. They now make the builders build a cavity in the outside wall which eliminates that problem. You might feel very reassured that half the master builders home of the year awards went to potentially leaky homes in the last twenty years. perhaps you might not want to know that or even question why there were no leaky homes in the days before treated timber was used. Macdunk

Serpie
18-02-2008, 01:06 PM
Thanks Phaedrus,
That's what I've been using, but I wasnt sure whether it was primarily a timber preservative, or a fungacide. I'm not keeping these houses forever, but I try to do everything properly so it lasts.
Much appreciated.

STRAT
18-02-2008, 01:25 PM
Hi Duncan, I knew I was starting something here LOL

Anyway Im no builder mate and will take anything you say with regard to building as being correct. I agree with all in your last post with one exception. "pressure differential"
Perhaps you could explain what you believe would cause a difference in pressure.

Im more than happy to go to a house of your choosing armed with a drill, some silicon sealer and a micromanometer to settle this one :D

Serpie
18-02-2008, 01:34 PM
I'm no aeronautical engineer Strat, but doesn't air passing over a structure create a difference in pressure between the top side and underside of that structure? That's why planes fly - because that pressure difference results in lift.
Therefore air passing over a roof will also create a pressure difference on the underside of that roof.
There's some pretty clued up people on ST - can someone confirm or rubbish that?

STRAT
18-02-2008, 01:42 PM
I'm no aeronautical engineer Strat, but doesn't air passing over a structure create a difference in pressure between the top side and underside of that structure? That's why planes fly - because that pressure difference results in lift.
Therefore air passing over a roof will also create a pressure difference on the underside of that roof.
There's some pretty clued up people on ST - can someone confirm or rubbish that?The short answer is yes.

An increase in velocity pressure will equate to a decrease in static pressure in order that total pressure remains constant ( relatively speaking ) the curve on the upside of the wing means the air passing over the wing moves at a higher velocity than the air moving over the underside of the wing so the static pressure on the lower face is higher than that on the upper face creating the lift. The faster you go the more lift you create. So air moving across and parallel to a roof would create a temporary pressure differential. This would mean for a moment the pressure in the roof space COULD become positive and the reason you sometimes see roofs just lift off in hurricanes. This is the opposite to Duncans argument though.

From a sparkies perspective Static pressure is kinda like volts and velocity pressure like amps with the total pressure being Watts and remaining the constant;)

POSSUM THE CAT
18-02-2008, 01:49 PM
Serpie A few drops of oil of cloves in a spray bottle of water will kill most household mould or mould on clothing. I have no idea of strength needed for timber or the time needed for the timber to dry. Go in to a good bookshop and ask for the cleaning book by Shannon Lush it will possibly give you more detail. Oil of cloves can be obtained from a Chemist.

Serpie
18-02-2008, 02:19 PM
Thanks Possum,
Will have a look next time I'm in Borders.

Strat,
That's why you get paid the big bucks mate - for talking in a language that no one understands.

Joe King
18-02-2008, 02:20 PM
Congratulations to all contributors to this thread, it would have to be the most interesting thread I have come across in any of the share forums for yonks.
Actually Dunk/Strat, perhaps "vacume" was innappropriate. My friend explained the problem was caused by expansion and contraction, more contraction in colder weather "sucking" in damp air which created undue moisture and mildew/mould. Better ventilation allowed the cavity to dry better.
Serpie, metalex will do the job. Works great on footrot/scald in sheep and tinea (athletes foot) too. Also a mild formaldahyde solution but it will probably kill the applyer first.

PTC. A bit of extra usuless information. Clove oil is also the most efficient organic treatment for varoa mite in bee hives as used in "Apilife Var"
Cheers
Cheers all
JK

duncan macgregor
18-02-2008, 02:20 PM
STRAT, If you think its rubbish feel free to buy a leaky home, and join all the other poor buggers bleating on about whoes fault it is. Take it from me i argued the point about leaky homes and why in the seventies its cost me a lot in lost business. I knew it was a problem then and why, now i dont care, none of it was my doing nobody beleaved me then why should they now. No leaky homes in the days of weather boards and untreated timber still standing today after a hundred years they at least knew to let timber breathe.
The sad part of it all is they have learnt nothing the building trade is a shambles.
STRAT take a table spoon and reverse it into a tap of running water. You will notice how it sucks the spoon in instead of pushing it out which is how a plane wing sucks the plane up. A roof has less air pressure in the attic if the wind is blowing on the outside. Take it from me the more airtight a exterior wall is in a wind rain situation the bigger the air pressure difference. next time you do a renovation take note of what happened to the building paper after a few years, or for a real shock what happened to the damp course under the wall plates. Macdunk

STRAT
18-02-2008, 02:38 PM
Duncan,
I dont think its rubbish and you know I have a lot of respect for you. Im not debating any of the points you have made with regard to leaky home symptoms and for the record my house was built in the 60s and nice and dry thanks ;)

Im not debating whether water is drawn/pushed into houses defying gravity in many circumstances as I know it is. I am also aware that building practices are largely/mostly responsible for the problems. I agree that a key solution is that the spaces are able to breath.

Im simply putting forward an argument for arguments sake that with a few weather orientated exceptions the wall cavities and the roof space in a house will have a static pressure = to the static pressure outside and that differential pressure alone can not be the reason for leaks and there must therefore be other contributing factors at work here.

minimoke
18-02-2008, 03:20 PM
Trouble is in NZ we get a lot of weather and its almost always blowing. Saturday torrential downpour floods with big southerlies and neighbours with the fire on. Sunday, no clouds, not enough wind to lift a kite, time for a swim, today a light 3.5km breeze.

Found this example:
“It is not the wind that blows your roof off, it is the higher pressure still air inside that blows it off. Even with just a 0.1 psi (pounds per square inch) pressure differential adds up, that works out to 14 psf (pounds per square foot) and in a typical house, with perhaps 2000 square feet of area under the roof, that totals more than 14 tons of force. Imagine 10 cars parked on your roof, except in this case they are pulling up instead of pushing down. Venting can help to equalize this pressure differential.”

Year of the Tiger
18-02-2008, 08:49 PM
I see this thread has been sort of high-jacked along the "leaky homes" line and it is so interesting to read the opinions of those in the know....

I think the score so far is
STRAT - (who is into "pressures regimes stuff") 9
Duncan - Chippy 5
Umpire Serpie - Sparkie.... lots of soothing attempts to keep the peace.:D

C'mon, just kidding guys...

Anyway....
I've been looking at a Mortgagee Auction on an Apartment and when I went to have a look at it, I find the whole Apartment Building is in the middle of a 'leaking home' saga.

The Apartment block is approx. 15 years old, very well presented and has location, location, location.

Trouble is, the wet walls etc... :(

Remedial work is currently underway (approx 2.5M worth) and should be completed around August. The Body Corp, Contractors and Owners are working very closely with Council and a Legal Action is underway to try and re-coup some of the remedal work costs and this should get to arbitration soon, expected end date early 2009.

The apartment I am looking at is being sold up by the financial lending institution... not one of the main banks in NZ, e.g. BNZ, ANZ, Westpac.... in fact the name given to me by the Realtor didn't ring a bell...

The proceeds from the sale will NOT pay the costs to the Body Corporate that have been due by the owner for 18 months or more for his share of the remedial costs. At this stage the remedial costs, interest and legal fees due by this Apartment are currently sitting at in excess of $78,000. The body corp manager has told me that the building repair will go over budget and the figure he gave me yesterday for the over-runs for the apartment I am looking at is somewhere between $6,000 - $7,000. (So far!!!!)

So, the story at this stage is to buy at auction then have to pay roughly $85,000 to clear the debt to the body corp.

Now, the apartment itself is very nice, but filthy. The Asian onwer flitted back to China about 18 months ago and the debts have risen since then... He had it rented to a couple of Asian students and it is obvious they didn't care too much about keeping the place clean. But hey, a bit of Jiff and some elbow grease can sort that out. It will need new carpets (due to the leaking debacle that has caused water to invade the property on the Eastern side). and I'm not too sure of the working condition of the applicances.. Smeg)

I think at this stage I have decided to walk away from the place due to the following reasons:

1. The unknown cost of what might just crop up between now and when the remedial work is completed.
2. The price that I would be prepared to offer is well below the figure that agent is saying "it should sell for". (And I'm not just talking 10 or 20K below....I'm talking 100K).
3. Even when the remedial work is completed, there will always be the stigma attached to the building because of the leaky building thing... I seek macdunk's professional opinion on whether a building can ever get a clean bill of health or is it forever doomed?)
4. I see in the documents of Body Corp meetings that the owners are seeking compensation for "stress and suffering they have endured". I think to myself, do I want to pay money to take over someone elses stress and suffering?

At the end of the day, I am sure I have made up my mind. I just thought I would post on here to tell of my very limited experience in this sort of thing, but to show how much info you can find out by asking questions.

Thanks for reading my ramblings.

YOTT

STRAT
18-02-2008, 09:02 PM
Hi YOTT,
IMO you have made the right decision not buying based on the little info supplied.

Couple of things to consider if you did buy
Once the repairs are done this probably will not guarantee that is the end of it. If further problems surface it could be round 2 for the building owners.
If you are taking a punt on such a thing you will probably be tied into it till the issues are resolved 2009 of later and the whole time in an uncertain market.
You would want to have a huge safety margin in the purchase price something like market value less the expenses to body corp less 20% market uncertainty less 100k for your trouble and stress.

Serpie
18-02-2008, 09:09 PM
And if the tipsters are right then you're coming into a buyers market YOTT, so no harm sitting on your cash for a while and seeing what else comes up. Nice position to be in.

tobo
18-02-2008, 09:57 PM
Wow, this is what makes NZ the place it is. We all have an opinion on house construction...I mean, it's not rocket science, right?
I work in the construction industry (as an architect) and am impressed at Dunc's understanding of vapour transfer through building walls. And Strat's 'static pressure'.
I'm sure this disagreement is a matter of terminology. I think Dunc is partly referring to the fact that air round a house is not still air and, just as they wind-tunnel test cars for votexes and wee flurries around wing mirrors, there are gonna be tiny suctions going on all over the place, sucking water through cracks if there's water handy.
So Strat, I don't know what you call that in technical air pressure lingo.
But the cavity is there to dry out the internals of the wall if any water gets in. We put a vapour barrier on the inside of the wall structure, but as Dunc says, we must be dreaming if we think we can make an entire building air-sealed

Actually this thread raised so many issues I'm trying to control myself not to react.

- Tobo. (I also know sommit about acoustics ... I play drums)

PS YOTT, I agree with Strat, based on info, not worth risk of potential problems. (I advise friends looking at apartments to not even consider it unless it's all precast concrete walls, but that's being conservative because I know I'm not gonna be there when they are lookin.

STRAT
18-02-2008, 10:15 PM
I'm sure this disagreement is a matter of terminology.


Actually this thread raised so many issues I'm trying to control myself not to react.


(I also know sommit about acoustics ... I play drums)



Re terminology Im sure you are right there Tobo


Dont hold back Tobo, Get into it.


A drummer eh? Your neighbours must hate you even more than mine hate me:D

George
19-02-2008, 05:39 AM
Who needs anything with a body corp involved. The name alone
makes me nauseous.

duncan macgregor
19-02-2008, 07:41 AM
Duncan,
Im simply putting forward an argument for arguments sake that with a few weather orientated exceptions the wall cavities and the roof space in a house will have a static pressure = to the static pressure outside and that differential pressure alone can not be the reason for leaks and there must therefore be other contributing factors at work here.STRAT The reason leaky homes started in the late seventies is simply because of the new type of building that was introduced to the unsuspecting public. some builders myself included, argued, pleaded, and did everything we could to bring it to the attention of the people setting the standards.
My own brother in law in Hamilton asked me to inspect a house before they bought it before leaky homes was even an issue. I told him for christ sake what ever you do dont buy it. Needless to say even my own family wouldnt listen, the house has now cost him a fortune, and is a leaky home. It is all pressure related with untreated timber not allowed to breathe end of story.
The only way to fix the problem is pull that plaster crap off the outside, and replace it with weatherboards or some other cladding that allows the pressure to equalize. Thats why when you want that spanish plaster look on a wooden frame you must now have a cavity. The pressure on the wind wet side is greater than the pressure inside your roof, walls, inside your house and even on the outside of the sheltered side. You would be surprised at how a pin hole in circumstances like that can leak so much water, even up hill.
Untreated timber must be allowed to breathe, otherwise even in dry situations lack of ventilation can cause all sorts of problems and health hazards.
YOTT, Dont whatever you do buy a fixed up leaky home, there is no such thing as i told my brother in law. Unless they change the exterior cladding to something that allows air to equalize you will still have a leaky home. Macdunk

minimoke
19-02-2008, 02:49 PM
....

When in doubt always get your own professionals to check it out. It is worth the few hundred dollars to save hundreds of thousands.

And that’s kind of where my sympathy runs out – except for the rate payers will fund an ever increasing bill and builders in the future who have to put up with more compliance red tape. So many properties have sold during this past boom without a registered valuation, nor any kind of building check in an effort to keep a competing bid at bay. But now those hasty buyers want our sympathy and money

Year of the Tiger
19-02-2008, 07:21 PM
Thanks Guys, I really appreciate your comments and I'm now totally convinced that I've made the right choice.

Cheers
YOTT

Steve
19-02-2008, 07:27 PM
And that’s kind of where my sympathy runs out – except for the rate payers will fund an ever increasing bill and builders in the future who have to put up with more compliance red tape. So many properties have sold during this past boom without a registered valuation, nor any kind of building check in an effort to keep a competing bid at bay. But now those hasty buyers want our sympathy and money

I agree Minimoke. A numberof them have jumped in without doing the basic homework, while blinded by the potential $$$ they could make. So it is a bit unreasonable for them to be expecting sympathy or a financial bail out... :o