Author Topic: Tornado Alley  (Read 14960 times)

PRR

Re: Tornado Alley
« Reply #20 on: May 25, 2013, 01:22:35 AM »
> ground rods buried into the holes, then bonded to the house wiring at each end.

Should be bonded to the fusebox or service entrance. Not to circuits. #8 or #6 from rod to the ground bus AT the main box.

Apologies if I've misunderstood.

> engineers designed grounding grids in the 18-in of clay that surround the buildings

Not too unlike my situation. (20 mil plastic, 20++ feet rock, no great difference.) At some point you really approach a "glass floor" situation. Then it becomes "impossible" to have large stray ground current. If you stand on glass and hold a live wire, no shock. The clay could conduct a lethal current to the perimeter of the campus to Earth, but grounding grids around all likely shock-zones mitigates that. In a lighting hit, the whole building is raised above distant ground by the stroke current times the impedance of the utility feeder. I guess in your case this could punch holes in the plastic.
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PRR

Re: Tornado Alley
« Reply #21 on: May 25, 2013, 01:33:16 AM »
> the devastation seen in OKC.

What you see in the overhead photos of OK is largely "manufactured houses". They are mass produced in a factory and very competitively detailed. In other words: they are equally strong everywhere. Stick-built houses tend to be strong in the panels and weaker where planes coome together. My site-built house would lose its roof then 4 walls fall outward. Large chunks. A manufactured house will hold together and then splinter in every part. Toothpicks.

> ...our standard constructions techniques ... Too expensive techniques for the american market I guess.

No; there's houses built here very much like yours.

Main difference is your mild climate. In the USA we need insulation, either for cold or for heat. Though there are areas where a masonry block wall is acceptable.
« Last Edit: May 25, 2013, 12:12:07 PM by PRR »
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Jdansti

Re: Tornado Alley
« Reply #22 on: May 25, 2013, 01:57:50 AM »
>I guess in your case this could punch holes in the plastic.

I'll have to check the design docs to see if the engineers considered this. ???  It's 40mil HDPE (20' wide bolts overlapped at the edges, double "welded" and leak checked).  I imagine that "punch throughs" could be possible given the energy in a lighting strike. There's 4' to 8' of compacted clay under the liner shaped into 4 grassy mounds (no trees) across the 80 acres to facilitate drainage. We have three buildings at the peaks of three of the mounds with equipment in them including variable frequency drives (VFD) and associated VFD pumps (we pump and treat contaminated groundwater). I don't have evidence of direct lightning strikes on the buildings, but the RF from nearby strikes often trips the VFDs into error mode when we have electrical storms.  There's a power pole just outside the perimeter of the liner that has to have its big fuses that hang at the top of the pole replaced about 4 times a year due to lightning.
R.G. Keene: EXPECT there to be errors, and defeat them...

mac

Re: Tornado Alley
« Reply #23 on: May 26, 2013, 11:44:40 AM »
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Toothpicks.

 :D
I hope Maine is far away from atlantic ocean´s hurricanes path...

Quote
Main difference is your mild climate. In the USA we need insulation, either for cold or for heat. Though there are areas where a masonry block wall is acceptable.

Patagonia isn't a mild place, nor the stifling northeastern provinces.
We have the same insulating needs you have.
It's not only a matter of $$$, but of uses and costumes of each nation as well, ins't it?
If british invasions of the Rio de la Plata in 1806 and 1807 would have been successful, our houses would be all wood instead all bricks!!! (and my english better)

Wood is a better insulator than a solid brick of the same thickness.
We use hollow body red clay bricks that have similar or better thermal and noise insulating capabilities than wood.
IIRC in the recent years light weight bricks were introduced. They are porous as wood, and lighter than clay or concrete bricks.
In my country they are rarely seen because hollow bricks are far more cheaper, even than wood.

mac

mac@mac-pc:~$ sudo apt-get install ECC83 EL84

PRR

Re: Tornado Alley
« Reply #24 on: May 27, 2013, 02:06:17 AM »
> If british invasions ..., our houses would be all wood instead all bricks!!!

Maybe. England hasn't used much wood in houses for several centuries. They cut it all long ago. In North America we had "endless forests" so wood was used for everything. Even siding, which rots, but we have more wood. This went on from Maine to Carolina to Michigan. (Much of our "corn land" used to be forest; hard to imagine today.) With the transcontinental railroad we started axing the West. We nearly ran out, but by then the old clear-cut areas had trees again. Even so we in the North get lots of wood from Canada.

> We use hollow body red clay bricks that have similar or better thermal and noise insulating capabilities than wood.

I have known hollow red-clay block buildings.

In most of the US, that is not considered "insulation". We use a lot of fiberglass "wool". A house has 5 inches in walls, 10+ inches in ceiling (12cm/25+cm). In many areas there is another inch of plastic foam under the siding, to reduce heat loss through studs. In my bathroom re-do, I took the fiberglass out of the wall around the tub and put in 4 inches of foam (about double the insulation of fiberglass; the 3X cost was worth it around a steel/tile bathtub).

Wiki has some nice tables. Yours are C-dominant and ours are F-dominant, seasons are reversed, some city tables don't track mean temperature, so I won't try to summarize too much.
http://en.wikipedia.org/wiki/Mar_del_Plata#Climate
http://en.wikipedia.org/wiki/Portland,_Maine#Geography_and_climate
http://en.wikipedia.org/wiki/Washington,_D.C.#Climate
http://en.wikipedia.org/wiki/NYC#Climate
http://en.wikipedia.org/wiki/San_francisco#Climate
http://en.wikipedia.org/wiki/Climate_of_Chicago
http://en.wikipedia.org/wiki/Fargo,_North_Dakota#Climate

In my numbers, you go up to 80 and down to 40 (with 15 and 103 records).

Washington DC ranges up to 88 and down to 29. Several deg C further than you either way.
San Francisco is known for cool mild climate: 71 to 46, smaller range than you.
Chicago runs 84 to 18.
NYC from 84 to 26 (a bit cooler than Wash DC).
Fargo ND runs 82 to zero. (Not a major city, but inspiration for the tornado scale.)
I'm a bit(?) north of Portland ME but those numbers will do. That's on the coast. Inland can be much rougher.

Outliers:
http://en.wikipedia.org/wiki/Needles,_California#Climate - Summer can average 108F (42C) with peaks to 125F 52C. Insulation to hold the cool in.
http://en.wikipedia.org/wiki/International_Falls,_Minnesota#Climate - Average 5 deg F *below* in January and proud of it. Record 40 deg *below* (either C or F!).

> I hope Maine is far away from atlantic ocean's hurricanes path...

Mostly they hit from Central America to Boston. If not, they go toward Greenland, miss me. When a hurricane comes over land, its energy supply is cut. The winds drop. So does ALL the water that has been suspended high in the sky. Several recent hurricanes came hundreds of miles inland (technically no longer hurricanes) and caused major flooding. Parts of Vermont and New Hampshire washed away. That one passed 100 miles west of me and was a really-really rainy windy day, with trees down.

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Jdansti

Re: Tornado Alley
« Reply #25 on: May 27, 2013, 05:03:59 AM »
>In most of the US, that is not considered "insulation". We use a lot of fiberglass "wool". A house has 5 inches in walls, 10+ inches in ceiling (12cm/25+cm). In many areas there is another inch of plastic foam under the siding, to reduce heat loss through studs. In my bathroom re-do, I took the fiberglass out of the wall around the tub and put in 4 inches of foam (about double the insulation of fiberglass; the 3X cost was worth it around a steel/tile bathtub).


After hurricane Ike damaged our roof, we decided to enclose and lay a slab in a 12x24-ft open air atrium located in the center of our house. The insulation they used in the new ceiling and the walls that had now become outside walls was recycled denim batts. The heat loading calculations called for another 6-inches of blown cellulose in the flat parts of the attic for us to avoid having to increase the size of our A/C and furnace system.

Since the roof still had the original layer of wood shingles under the damaged asphalt shingles, the roofer had to rip everything off and lay down new decking. We chose a decking material that had a radiant barrier facing the attic space. We also got rid of the three whirlybird vents and had ridge vents installed, which provided a larger open area for ventilation to match the extra soffit vents I had added years ago. The coolest thing was the solar exhaust fan installed on the roof of the garage.  The down side was since the atrium formerly provided 80% of the natural lighting (very few exterior windows in the house), my wife insisted on two 4x5-ft skylights in the new atrium roof, which lets in much more heat than if there had just been roofing.
R.G. Keene: EXPECT there to be errors, and defeat them...

ch1naski

Re:
« Reply #26 on: May 27, 2013, 12:25:25 PM »
As for keeping the roof attached,  “Tico" clips and 48" straps are what we use for earthquakes here in Los Angeles. Keeps the framing and roof tied together pretty well. But, keep in mind the three little pigs.....
Mockingbird wish me luck.

Johan

Re: Sv: Tornado Alley
« Reply #27 on: May 27, 2013, 02:06:44 PM »
I'm really glad I live where I do. No severe storms, no earthquakes, no volcanoes. we worry mostly about keeping the heat inside in the winter, our roofes not collapsing from the waight of the snow and moisture destroying our wood constructions. As a consequence we build differently from most of the US. We expect our houses to stand for at least 100 years(my house was built 1911 ), but with the kind of winds we are talking about here, I doubt there is anything but a concrete bunker that would survive that timespan
J
DON'T PANIC

mac

Re: Tornado Alley
« Reply #28 on: May 28, 2013, 12:38:10 AM »
http://en.wikipedia.org/wiki/Ushuaia#Climate
http://en.wikipedia.org/wiki/Santa_Cruz_Province,_Argentina

What the do there is to use double walls of 8cm hollow red bricks, with fiberglas wool or expanded polystyrene between the bricks.
Same below the roof tiles or steel shets.
By themselves wood or bricks are not enough.

It's very difficult to compare insulating materials since in the case of bricks, it depends on the type of clay, the number of hollows and the thickness of the brick. Also the exterior waterproofing layer + lime, and the interior lime + plaster helps.
Where I live this is more than enough.
The only thing needing insulation here is my Ge FF because we have variatons of 15C in minutes...  >:(

mac


 
mac@mac-pc:~$ sudo apt-get install ECC83 EL84

PRR

Re: Tornado Alley
« Reply #29 on: May 28, 2013, 02:37:11 AM »
> depends on the type of clay, the number of hollows and the thickness

So I see. I've been looking around.

Around 1920 there were major suppliers of terra-cota (fired red clay) blocks in the US. I knew several buildings made with this stuff. Blocks were cheap and light so walls were thick. But the cell-hollows inside were simple circles or squares. Significant air convection inside each cell, and significant conduction through the cell walls.

I found a German (or Swiss?) block maker and their inner walls were all parallel to the face with thin spaces which discourage air convention inside the cells, and thin side walls giving little direct conduction. Really very artistic! And must demand a very good grade of clay, very well processed, to form those thin walls without a lot of trouble in the extruder or the kiln. Apparently some buildings use only clay block (no wool/foam) and get good thermal performance. (This may be more true of multi-unit apartment buildings with only limited outside exposure per tenant; here I heat all four walls but back at the apartment I only had one wall.)

There's also real difference in fire rating, though the statistics didn't show a huge difference in fire losses. (Germany 80% block, 10 fires/million population; USA 80% wood and 20 fires/mill; you would expect a bigger difference; also the USA has some of the world's worst wiring and poor enforcement of wood-stove safety.)

A real factor is the price of wood. I got a quote last summer for paneling, $0.80/ft. I bought this spring: $1.15/ft. I thought the store made a mistake: Apparently I missed the spike to $1.30 the month before. I have a table of HomeDepot wood prices from a year ago, and ALL lumber prices are up 20%-40% in a year. I guess it means the recession is fading (more home construction than in recent years) but this roof over my lawn-tractor is costing more than the tractor is worth! Maybe time to build a brick out-house?
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mac

Re: Tornado Alley
« Reply #30 on: May 28, 2013, 08:15:51 AM »
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A real factor is the price of wood. I got a quote last summer for paneling, $0.80/ft. I bought this spring: $1.15/ft. I thought the store made a mistake: Apparently I missed the spike to $1.30 the month before. I have a table of HomeDepot wood prices from a year ago, and ALL lumber prices are up 20%-40% in a year. I guess it means the recession is fading (more home construction than in recent years) but this roof over my lawn-tractor is costing more than the tractor is worth! Maybe time to build a brick out-house?

Here wood and bricks walk hand in hand, same $$$/m2 rate!!!  >:(

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There's also real difference in fire rating, though the statistics didn't show a huge difference in fire losses. (Germany 80% block, 10 fires/million population; USA 80% wood and 20 fires/mill; you would expect a bigger difference

I was in Berlin a couple of times, and in my limited experience, I saw a lot of wood inside their buildings, like floors and stairs.
Any german member reading this thread?  :)
 
mac
mac@mac-pc:~$ sudo apt-get install ECC83 EL84

Johan

Re: Sv: Tornado Alley
« Reply #31 on: August 08, 2013, 01:18:17 PM »
just because we discussed house construction...we are tearing down an inside wall in our house..this is nothing like the paper walls we see in hollywood movies...but I realize hollywood might not have much to do with the true story..8)
J
DON'T PANIC

Johan

Re: Sv: Tornado Alley
« Reply #32 on: August 08, 2013, 03:16:14 PM »
DON'T PANIC