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The Artful Bodger
07-11-2014, 02:37 AM
Can you see any flaws in this scheme?

http://tvnz.co.nz/national-news/christchurch-city-council-testing-houses-flooding-6024347


In a New Zealand first, Christchurch City Council is deliberately flooding a home to test new waterproofing technology.

If it's successful it could be rolled out as a protection option for homes in flood-prone areas like Flockton basin.

A council home was sprayed with a special waterproof coating and tomorrow it'll be flooded to find out just how waterproof it is.


(Christchurch was devastated by an earthquake about 3 years ago and thousands of houses were destroyed or rendered uninhabitable by liquefaction and other land problems. This flood protection scheme is one of the ideas being tried to ease the plight of houses that are in areas now prone to flooding due to changes in land and water table levels.)

:confused::confused::confused::confused:

awemawson
07-11-2014, 03:30 AM
Houses will float off their footings

The Artful Bodger
07-11-2014, 03:53 AM
They will if water gets underneath them, which I expect it will, but they did mention sump pumps.

boslab
07-11-2014, 04:57 AM
I would guess that condensation would turn the house into a mould growing facility over time, many houses over here have suffered that due to lack of ventilation of the wall spaces, damp intirior walls covered in black mould.
Mark

The Artful Bodger
07-11-2014, 05:58 AM
.....deleted by me...........

flylo
07-11-2014, 07:16 AM
Wall & ceilings need to breath or mould & rot occur like when they wrapped houses in plastic here in the '70s.l

SteveF
07-11-2014, 07:33 AM
Every few years my insurance company calls to tell me that I don't have flood coverage on my home owners policy. My response is always "That's because I don't need it because I'm not so stupid that I would own a house that could get flooded".

Steve

Paul Alciatore
07-11-2014, 07:40 AM
What about back-flow through the drains/sewer? Or don't they have indoor Johns there? I mean, I have seen just a foot or two of head lift cast iron manhole covers when the flood water reaches the storm drains and it flows backwards.

A.K. Boomer
07-11-2014, 08:44 AM
Can you see any flaws in this scheme?




Yes, Cancer ? and for 20K You could build a retaining wall around the entire place and keep it totally dry... and have 10K left to go out to dinner...

Rustybolt
07-11-2014, 09:15 AM
Houses will float off their footings


Yep. Better to let the basement flood. If your getting enogh ground water to float a foundation I doubt you can dig a sump big enough.

jep24601
07-11-2014, 10:06 AM
Waterproofed basements have (or should have) extended footings to the exterior to hold them down against flotation . Nothing wrong with what is proposed here.

lakeside53
07-11-2014, 11:26 AM
Not many (if any) "basements" in Christchurch's low lying areas ;) Usually slab-on-grad or rim foundation with piles if older.

loose nut
07-11-2014, 12:03 PM
Just build a barge on your land and a house on top of it. No more flood problems as long as you put out anchors.

epanzella
07-11-2014, 12:52 PM
For 20K you could jack the house up and put a concrete foundation under it. That spray is a joke. The clapboards will flex from the water pressure and the seams will open. Even if you could get it to work when the coating is fresh, how do you check the integrity as the seasons go by and the wood shrinks and expands with the seasons.

krutch
07-11-2014, 01:34 PM
I visited a friend who was living in a trailer house. He had wrapped it in plastic against the winter. I mean the whole trailer! When I got there several people were visiting and no one had a working lighter. One guy close to the door was attempting to light a cigarette when the door opened and the lighter fired up like a blow torch. I laughed and told the guy to open an oxygen hole in the plastic. They could have suffocated without realizing it.

Bob Fisher
07-11-2014, 02:26 PM
Seattle has the solution,concrete basements that float, they also have a bridge supported by hollow concrete floats. They put a stop to it because they couldn't find a way to tax the property the homes, net the bridge. Bob.

Rustybolt
07-11-2014, 02:30 PM
Waterproofed basements have (or should have) extended footings to the exterior to hold them down against flotation . Nothing wrong with what is proposed here.


Enough water can lift anything.

The Artful Bodger
07-11-2014, 03:56 PM
Yes, it really is a daft idea and I thought so immediately I saw it on TV.

Few if any of the houses in that part of Christchurch have basements, the older houses will have a perimeter foundation beam and piles, more recent houses (last few decades) are on concrete pads (single slab for example).

The problem they have is that the houses were perfectly satisfactory, never flooded, for a century or so but the earthquake changed everything.

kendall
07-11-2014, 04:32 PM
On a job site there was an in-ground swimming pool that had been drained. The owner had plugged the drain hole because water kept coming back in. I mentioned that I had seen them float out of the ground and that he should open the drain back up, he said I was full of it because the pool was all concrete and too heavy to float. I told him that they made plenty of concrete boats, and some companies still made them. He said BULL. Next day we came in for work, and the pool was about 16 inches out of the ground on the deep end.

Along the James river after a hurricane years ago, the insurance company paid to have the houses lifted up and placed on stilts. Was a better solution to the problem.
With some of them we were hired to build walls so the owners could use the area under the house as garages and rec-rooms. Seemed to contradict the reason behind the stilts.

Mike Burch
07-11-2014, 06:03 PM
This test is being carried out in a part of Christchurch that was lowered about two feet by the recent earthquake, so one can hardly blame the residents for having bought there in the first place.
There are two main problems with the idea. One, it won't work, and two, they have blocked up all the vents which are there to allow air to circulate under the floor to prevent dampness causing rot. These houses do not have basements, they just have wooden bearers on top of the piles (either wood or concrete) that are set into the ground. The floor joists sit on the bearers, and the floor boards on top of the joists. So there's a lot of wood under the floorboards, and it all needs to be ventilated to prevent rot. Closing off the vents is fatal.
I don't know who's paying for this stupid test, but I would be very surprised if it's not the taxpayer.

jep24601
07-11-2014, 08:00 PM
Enough water can lift anything.

Nonsense! It's a completely common design issue.

A.K. Boomer
07-11-2014, 08:18 PM
Like Epenzella stated it's a joke ---


" That spray is a joke. The clapboards will flex from the water pressure and the seams will open. Even if you could get it to work when the coating is fresh, how do you check the integrity as the seasons go by and the wood shrinks and expands with the seasons. "

i'll reiterate - it's crap, its bogus, it's a bass awkward way of trying to get something done and logical physics on so many levels will slap it directly in the face...

Rustybolt
07-11-2014, 10:38 PM
Nonsense! It's a completely common design issue.


I'm sure it is. " A body immersed in water will displace an amount of water equal to its own mass."

lakeside53
07-12-2014, 12:03 AM
No. Not its mass - its volume.

But that doesn't mean it will float!

An iron bar displaces the same water as its volume, but doesn't float.

Mike Burch
07-12-2014, 01:14 AM
I'm sure it is. " A body immersed in water will displace an amount of water equal to its own mass."

Ahem... "A body wholly or partially immersed in a fluid experiences an upthrust equal to the weight of fluid displaced."

Which is why ships, for example, float in water (but not in air), despite being made of steel. The hull (which is largely hollow) displaces a volume of water the weight of which exactly equals the weight of the ship. The upthrust therefore equals the weight of the ship, which therefore floats.

A hollow concrete tank like the ones in my sewage system might weigh a couple of tons, but that's the weight of only two cubic metres of water. The tank will be almost entirely hollow, and will occupy far more than two cubic metres. Therefore it could easily float out of the ground in a heavy enough downpour unless it's full of heavy liquid. Which is why I had to empty my freshwater tanks into my sewage tanks the moment the latter were installed, just to make sure they stayed installed.

Yow Ling
07-12-2014, 06:43 AM
I watched it on telly the other night, someone has figured out a way to tap the council for some money by solving the last embarrassing issue, the so called Flockton Basin. Should just bulldoze them and buy them out. Reminds me of giving carrot juice to cancer patients , gives them some hope. Ive lived in Chch since 1974 had never ever heard of Flockton , now its a suburb , amazing the power of out of town media.

If they sprayed that stuff on the inside you could fill the houses with water and use them to replace the pools that were damaged in the quakes.

Rustybolt
07-12-2014, 07:40 AM
Sorry. Volume.
I've seen basements pushed up by water pressure. Just the pressure from a foot or two of water surrounding a sandbagged house lifted the foundation. I;ve helped repair the damge of a water main break under the floor of an industrial building. Broke up a piece of slab and lifted it over six feet in the air. water can move anything.

Black Forest
07-12-2014, 08:48 AM
I wonder if the material they are spraying is the same material that gets sprayed on roofs? We had a metal roof sprayed in Texas 20 years ago and it is still water tight. This was sprayed over some rusty corrugated metal with pin holes. I didn't think it would work but I tried it as the company was in business for a long time and gave a guarantee of 10 years. And it was much less expensive than re-roofing the old barn.

Yow Ling
07-12-2014, 04:49 PM
For 20K you could jack the house up and put a concrete foundation under it. That spray is a joke. The clapboards will flex from the water pressure and the seams will open. Even if you could get it to work when the coating is fresh, how do you check the integrity as the seasons go by and the wood shrinks and expands with the seasons.

Around here 20k wouldn't even get close to paying for the engineers report, then you need a resource consent etc
They have looked at jacking houses to replace the fractured foundations they more like 200k about 50% of replacement cost
Short term rentals are $600 to $1000 per week , say 10 weeks to fix broken house , plenty of money on the magic roundabout in Christchurch

The Artful Bodger
07-12-2014, 05:37 PM
Yow Ling, they should give it all back to the eels and paradise ducks! Earthquakes are nothing new in Christchurch as even the earliest settlers wrote letters home complaining of them.

Paul Alciatore
07-12-2014, 05:49 PM
I lived in a travel trailer in Iowa for 16 years. I did some extra insulation and winterproofing and was worried about making it too tight. One thing I did was add plexiglass panels on the windows for extra insulation. But I skipped the front, sloping window and even kept it open a small crack at all times. The roof mount AC units probably also leaked air. I also had CO2 detectors. Never had any trouble from lack of oxygen.



I visited a friend who was living in a trailer house. He had wrapped it in plastic against the winter. I mean the whole trailer! When I got there several people were visiting and no one had a working lighter. One guy close to the door was attempting to light a cigarette when the door opened and the lighter fired up like a blow torch. I laughed and told the guy to open an oxygen hole in the plastic. They could have suffocated without realizing it.

kendall
07-12-2014, 10:42 PM
I lived in a travel trailer in Iowa for 16 years. I did some extra insulation and winterproofing and was worried about making it too tight. One thing I did was add plexiglass panels on the windows for extra insulation. But I skipped the front, sloping window and even kept it open a small crack at all times. The roof mount AC units probably also leaked air. I also had CO2 detectors. Never had any trouble from lack of oxygen.

Bad idea to over insulate a trailer if in the snow zone. There are 6 mobile homes that collapsed last winter within walking distance of my house.

RoyClemens
07-13-2014, 08:11 AM
For you guys that are building footings that will not float up, Keep in mind that now you need to make the floor and the walls stiff enough that they don't bend. At least not very much. I'm not enough of an engineer to calculate how thick of a slab you would need for the floor of this boat that is not going to float, but I bet its a lot more than 4 inchs.

Roy

flylo
07-13-2014, 09:47 AM
Well did it work? I thought they were going to film a follow up or did I miss it?
BTW A/B do you know Sue Mciver in her 50s, used to work with my wife.


Can you see any flaws in this scheme?

http://tvnz.co.nz/national-news/christchurch-city-council-testing-houses-flooding-6024347




(Christchurch was devastated by an earthquake about 3 years ago and thousands of houses were destroyed or rendered uninhabitable by liquefaction and other land problems. This flood protection scheme is one of the ideas being tried to ease the plight of houses that are in areas now prone to flooding due to changes in land and water table levels.)

:confused::confused::confused::confused:

The Artful Bodger
07-13-2014, 04:06 PM
Sorry, I dont know any Sue McIver.

We have not seen any updates on the project which either means it did not work or the TV people are not interested (which might mean that it did work!).

Mike Burch
07-14-2014, 04:12 AM
The TV news tonight reported that the trial was successful, inasmuch as the coating kept the water out for a couple of days. However, they're now admitting that it's useless in its present form, as all the sub-floor vents have to be blocked up before the rain starts, and portable dams erected in the doorways, and so on and so forth.

The Artful Bodger
07-14-2014, 04:25 AM
Mike, I want some of that paint for a leaky shipping container I have!

Norman Bain
07-14-2014, 05:27 PM
The paint looked very much like the goo that I used to paint a concrete swimming pool some years back.

Mike Burch
07-14-2014, 06:02 PM
A bright blue shipping container, John?! (Though they did say in the first report that it's also available in white.) Is this at your place or at the aerodrome?
It seems that the Christchurch City Council organised and paid for the experiment, so they should be able to tell you where to source the stuff.

The Artful Bodger
07-15-2014, 12:33 AM
Mike, we have two containers at the airport that have serious leakage problems and we can only keep them moderately dry by chaining the doors partly open (it is amazing what a difference that makes).

The one with the really rusted roof I covered with plastic and poured sand on top to keep the plastic down. I earned quite a bit of ridicule for that little 'fix' but no one was going to vote the $$$ needed for a real job. I am somewhat reluctant to check the inside conditions of that one!

I do have a container here at the house which we used for our move from the Windy City, it is insulated with an aluminium skin and a few leaks from damages to the roof. I 'fixed' those with my bodge of soaking strips of old bed sheets in house paint and laying them over the holes. Unfortunately the bed sheet eventually rots but it is good for a few years.

wtrueman
07-18-2014, 12:13 AM
Hi all: I have been away for a while on my leaky Al. Boat. So what is this spray called? Thanks for your time,
Wayne.