Dear Ones,
I am building a home on the <!—-><!—-> <!—->Oregon<!—-> <!—->Coast<!—-> <!—-> that I intend to grow old in. Building here presents several challenges:
* Category D wind loads (up to 100 mph)
* Tsunamis
* Mold and mildew – caused in part by standing water under houses
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I think the right approach is to build an insulated “short basement†or plenum under the house. A plenum becomes the return air system for the forced air furnace which will probably reside in this 30†high crawl space. This requires a concrete slab between the foundation walls. The return air vents for the first floor are simply holes in the floor with grates. This would keep the underside of the house dry, avoiding the musty smell of the typical beach house, while providing warm floors for comfort.
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In the case of a tsunami, if the house survives the initial event, the most immediate problem will be getting the water out of the house before it warps the floors and ruins the interior. If I include a foundation drain in the floor of the plenum, the plenum will become a big bathtub. All the water would run through the floor vents into the plenum and drain away to the sea. The house could be free of standing water within minutes.
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In order to maximize the view while standing up to wind and waves, I think the foundation walls should come up to the window sills. For shear strength the window wall on the ocean side would be in a steel frame firmly anchored to the foundation. The house will sit on a 20’ bluff above the sea that will help break the force of the waves. If I use hurricane glass and perhaps some drop-down shutters the windows might stand up to a tsunami.
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Please don’t get the impression that I know what I’m talking about. I’m sort of a hobby builder and would really appreciate any ideas from you guys who do this stuff for a living.
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What do you think?
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<!—->Douglas Cochrane<!—->
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<!—->“When the wind stops blowing in Yachats, the cows fall down…”<!—->
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Replies
The other day on a show called "The Daily Planet (Discovery Channel)" there was a clip about some people that have designed houses to survive tsunamis for the people in South Asia. They are masonry houses that have the openings front and back to allow the wave to flow through the house without knocking it over.
There was footage of tests done in a Wave Tank, of a conventional house and their house. The wave flattened the traditional design, but the new one survived. Keep in mind your going to have to have to go out into the neighborhood to hunt down all your belongings.
Short of getting a surplus Russian sub and bolting it down to a deep foundation, (make sure the hatches are closed) no house is going to survive a hit from a tidal wave unscathed.
The idea of building beach houses so that the water will flow under is not new. See attached pic. Typically the under house area would be screened with lattice or other "break away" superficial building material and this underneath area is used for parking and storing trashcans or other disposable type items. In the pic it looks like the house in the background didn't get the memo, but who knows, maybe the skirting is made to break away...
The house that I was trying to describe from the TV show was not a stilted house to allow the water to pass under. But a masonry house to allow the wave to pass through. Hence my reference to going into the neighborhood to find your belongings.Rather than go into more detail about what I saw on the show, I looked up their website and found the piece and another on topic that I hadn't. http://www.exn.ca/dailyplanet/view.asp?date=2/21/2006http://www.exn.ca/dailyplanet/view.asp?date=3/2/2006(They take a moment or two to start.)
that was neat. BOB thinks I,m an idiot
Wow, I'm amazed how generous you all are with your time and expertise. The ideas, pictures, and even video that you shared give me more to think about in designing our home.
Let me share a couple of thoughts:
Wind load is a very real factor. We see winds in the 75 mph range every year or two and have seen winds over 100 mph. Building a house on stilts to let a potential tsunami flow beneath it seems like an invitation to fly our house onto the neighbors land. Plus we have a 16' height limit under the CCR's so it isn't much of an option.
If we get hit by a 60' tsunami, we'll resurvey to find out what we still own and consider building again. But if we get hit by a moderate tsunami, say 20-30', the house might survive, given that we are on a 20' bluff. It is worth consideration in designing the house. I wouldn't spend a fortune on it but since we will be using some steel framing to handle the wind shear there isn't any reason not to make sure it is anchored down well to increase the potential for surviving a wave.
The video that QCInspector provided from Sri Lanka talks about letting the wave flow through the house. This concept has real potential. I wonder if we could even design some interior walls to break away under force?
As I tell my kids, if I die in a tsunami it will have been worth it to live on the Oregon Coast. Better a tsunami than a hospital bed!
Thanks again for your suggestions. Hopefully I can offer something useful in a future discussion.
Douglas
Have you thought of going with poured concrete walls and precast roof? Your asking for a lot. There is a big difference between the force generated by a little rain blown around by a hurricane and the impact of a wall of water hitting a house.
You may be better off planing for the 100 mph winds because there is a real possibility that may occur from time to time.
Getting hit by a Tsunami is rather remote odds. And by having a concrete structure you may have something to start over with.
But then again you may be better off just getting a really good insurance plan and flood insurance.
The Tsunamis damage is cause partly by the water flowing inland, but mostly it destroys flowing back out again... carrying a whole bunch of junk with it - like cars, trees, boats, etc. The main thing is to keep your house out of the way of that stuff as much as possible. Steel girder stilts down into a strong foundation, 1st floor is disposable space - garage, large dining room, open porch area, whatever. Bedrooms, offices, media centers are upstairs.
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
While living in Kodiak, AK it seemed that our high water mark from the 60ish earthquake was something like 63' if memory serves. Not much is going to be salvagable if all your personal belongings are subjected to that--might be better to simply plan a total rebuild in that case.
Even if the shell of your house survived, the whole works may be below the new beach level.
What height are the tsunamis likely to be in your area? If it's rather mild, say 15', that seems like a totally different beast than 60'. Also, what is the most likely behavior of the wave? From the reports, the Kodiak tsunamis was slow, like watching the tide come in, but it kept coming and coming.
Personally, I'd probably go with an ICF house since it's pretty easy to dry out and they're pretty durable, especially with a beefy upgrade in the rebar. As for the foundation, I haven't a clue since it requires something more than a typical footer.
Radiant heat in slab floors would eliminate having to dry out ducts or whatnot.
As far as saving your personal belongings from a major dunking, it sounds like a perfect situation to store photos digitally and keep valuables either on high ground or easily accessible for a quick getaway.
It is fun thinking about such things.
The current issue of the United Airlines inflight magazine (don't ask - it was a looong flight - LOL) has an article about a very cool dome house designed to withstand hurricanes in Pensacola Beach (click on Feature: Ultimate Houses Stand Up to Mother Nature):
http://www.hemispheresmagazine.com/indexflash.html
Here's some pics & another article:
http://www.csmonitor.com/2004/0922/p14s01-lihc.html
There is at least one dome designer on Breaktime (Cloud Hidden) you could chat with. Domes seem to be the best shape for deflecting the forces of nature.
I agree with most everything previous posters said. I would consider building on steel or reinforced concrete stilts with the break away lattice and using the first floor for storage of stuff I wouldn't care too much about if it got destroyed. I would also think of angling the house so the corner faces oncoming water (and the opposite corner faces water washing back out). I still doubt that would help in case of a tsunami--the forces are so incredibly great.
On the plenum idea--make sure if you have a plenum that it stays dry--otherwise you wil be pumping musty air and mold spores throughout your house!
A window that stands up to a lot is one made of glass block. I was working to remove drywall from a house near Biloxi recently where 7 feet of water rushed through. The glass block window was lying on the patio, undamaged--aprently the water washed it out of the frame and left it.
It's probably cheaper to buy insurance than to pay a lot of money up front to build a house that *might* survive a tsunami. Frankly, I doubt it would survive. I saw the houses in the lower 9th ward in New Orleans and they were totally flattened by a flood that was not nearly as strong as a tsunami.
Think about dropping your house in the middle of a strong river and ask yourself if it would survive.
Building a house on stilts definitely will help, if the water doesn't rise to the living space.
Billy
I can tell you this from hurricane katrina. If a house get hit by water wave, its gone, nothing you can do to stop it. concrete will not stop it. Better to build on high ground. wave will usually not go father than a mile inland, depending on slope of ground.. BOB thinks I,m an idiot
Good point--when I toured Biloxi recently, there were lots of piers sitting around--the houses that had sat on them were nowhere to be seen!
I'm no expert but it would seem to me that if you were to build a house out of icf blocks and reinforced the rebar in it along with sloping the roof line to a pitch that would allow the out going tide to ride up and over it ether puting the frist floor of the house in the ground etc. or building it on a main stilt that would allow you a higher level of ground like this house on an island in the souther carribian. This house has seen many hurricans in the last 20 years.
Edited 3/26/2006 12:33 pm ET by montana nate