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SheepDog

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This topic is about having a home that will protect you from the natural forces that exist in your area.
Here is a list of some natural disasters that might affect you:
1. Weather
a. rain that can cause flooding or landslides and the lightning that can accompany it
b. wind such as tornadoes or hurricanes or just very high local winds
c. snow whether it is a freak storm or an annual event
d. heat that goes dangerously high or for prolonged periods
2. Fire
a. forest, brush or grass
b. house fire from the inside or out
3. Earthquake in the USA there are very few spots where this is not a consideration and those areas have extreme weather concerns
4. Sinkholes from subterranean rivers and ground water loss
5. Tsunamis
 
We are pretty safe here. Arizona has no hurricanes and while tornadoes are possible, they are rare. The last person in AZ killed by a tornado was 50 years ago.
No way we could flood at our house. We do get snow in the winter but very little and if we were snowed in most of the winter would not hurt us.
Fire is an issue for everyone. Our house is almost new so the wiring is up-to-date. We have no large trees within 200 yards of our house (by design). I keep the grass and weeds mowed for some distance around our buildings to reduce fire risk.
It has been more than 130 years since AZ had much of an earthquake.

Not listed:
Do you live near a nuclear power plant? No, we are more than 200 miles from one.
Are there likely nuke targets near you? No, again many miles away and fallout drift maps show us likely in a safe area.
 
I live in an area that has a potential for moderate earthquakes (magnitude 4 to 6), annual periods with high winds (up to 100+ mph) and winters that occasionally bring snow and ice in amounts that are generally not severe but can be problematic. There is a slight danger of grass and brush fires.
I'll cover the earthquake first:
The house should not have "stub walls" which are short walls between the foundation and floors. These typically fail in even moderate quakes. The walls should be bolted to the foundation to prevent sliding off the foundation or lifting at the corners of the house. The exterior walls should have sheet sheathing that resists "racking" of the house under horizontal motion. These are called vertical sheer walls and you need at least 6 feet of shear wall from any corner in both directions. Doors and windows are interruptions in the shear wall and should be minimized and reinforced. Placing sheer walls on both sides adds to the rigidity of the wall. The floor plan should be as close to square or rectangular as possible and not longer than three times its width. Rooms or porches that extend out from the rectangle require twisting reinforcement at inside corners to prevent separation from the rest of the building. Floors and ceilings are also a type of horizontal sheer wall commonly referred to as "diaphragms". These diaphragms hold the shape of the house and keep it from twisting. The sub floor is the crucial bottom diaphragm because it connects under the walls to the foundation sill plate in a compete sheet (as long as it is a boxed flooring system. That just means that the floor has boards to fasten the flooring to completely around each sheet. It is common practice to not box the floor joists but the strength doubles with a blocked floor system. The roof is an integral part of the ceiling diaphragm and must be structurally fastened to the walls and foundation. Trusses and joists are typically fastened by "toe nailing" them to the wall top plates. This is the weakest connection possible and is not acceptable (to me) for earthquake or wind conditions. It was adopted years ago when it was thought that gravity held the house together and it does as long as the wind doesn't blow and the ground doesn't move. In my area type H-1 or H-2 cleats are code enforced but they are just small pieces of pressed steel brackets that nail into the bottom chord of the truss or rafter and then nail into the top plates of the wall. It is much better than toe nailing but offers little support against lift or racking of the roof that can occur with wind or earthquakes. Diagonals on the underside of the trusses or rafter will help prevent racking but do nothing for lift from wind or quakes. My answer is the H-16 ties that wrap around the upper chord of the truss or rafter and wraparound the two top plates and are anchored at the ends with nails or screws. There is little to no force on the screws or nails because the lifting forces have to go around two 90 degree bends before the fasteners are placed under tension of any kind. Diagonals are still necessary to stop racking of the individual rafters or trusses. Roof sheathing is typically 1/2" sheathing and although it does provide for moderate sheer resistance it is easily penetrated which allows wind under the roof that will blow large sections out from the internal forces especially when standard nailing practices are followed. I prefer construction screws instead of nails in all the wood construction due to the fact that common nails work out with vibration from wind, temperature fluctuations and moisture. Construction screws have none of these problems and have the same sheer strength as nails. They also have drill points that prevent splitting of the wood and tapered (counter sunk) heads that seal against moisture intrusion better than nails..

Additional steps that make the house more resistant to quake damage:
Full height ties that bolt to the foundation bolts and connect the top of the wall directly to the foundation.
Reducing the distance between the tie down bolts from 72" to 32" on center and have them penetrate the sill plate, sub-floor, and bottom plates of the wall..
Seismic "tape" triangulation of the walls and roof.
Double king studs (studs that go from the wall bottom plate to the top plates) at all doors and windows.
Full headers (stacked, glued and screwed beams that go over wall openings to transfer loads) over all doors and windows.
Blocking plates (nailing boards at sheathing joints) so sheathing is joined where edges meet in the walls.
Blocking plates in the roofing to join sheathing at the ends
Placing sheathing on both sides of walls adds almost 80% more rigidity to the wall adding strength to the sheer wall.
Using H-16 truss and rafter connectors and using a 7" construction screw (going up through the bottom of the top plates into the rafter or joists) to tie rafters or trusses to the wall.

Most of these tips are best performed with new construction but some can be retro-fitted to existing structures.
You can use anchor bolts to tie the foundation to the walls. You can sheath stub walls to increase their rigidity. If you remodel a room and have to replace drywall you can place sheathing on the studs first and then hang the drywall on the sheathing. When replacing windows you can add the extra king studs and header over the windows.
 
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Arizona, depending on where in the state you are is above 2 and up to level 6 for chance of a moderate earthquake.
You may also be in a place where seasonal heat could be problematic as well as seasonal flash floods.

Since bombs and power plant meltdowns are not natural occurrences I have not chosen to address those. Perhaps a future topic for another discussion?
 
Terri,
New Mexico shares the 2-4 level risk for moderate earthquakes that I live under. When I lived in Seattle it was considered a 6 to 8 level and I lived through two M7 quakes there.
With the threat of Cascadia destroying the infrastructure of the entire area I decided that there was no way to prepare for no water, food, power and fuel for a three year period in a densely populated area.
So I moved to a rural area far enough from the Cascadia area that any effects will be almost negligible.

A note on Arizona quakes: Since 1850, Arizona has had more than 20 earthquakes with magnitudes of 5.0 or higher. The U.S. Geological Survey reports that the largest earthquake on record in Arizona measured 5.6 in July 1959. Arizona, has had: (M1.5 or greater) 3 earthquakes in the past 24 hours 4 earthquakes in the past 7 days; 16 earthquakes in the past 30 days.
 
Terri,
New Mexico shares the 2-4 level risk for moderate earthquakes that I live under. When I lived in Seattle it was considered a 6 to 8 level and I lived through two M7 quakes there.
With the threat of Cascadia destroying the infrastructure of the entire area I decided that there was no way to prepare for no water, food, power and fuel for a three year period in a densely populated area.
So I moved to a rural area far enough from the Cascadia area that any effects will be almost negligible.

A note on Arizona quakes: Since 1850, Arizona has had more than 20 earthquakes with magnitudes of 5.0 or higher. The U.S. Geological Survey reports that the largest earthquake on record in Arizona measured 5.6 in July 1959. Arizona, has had: (M1.5 or greater) 3 earthquakes in the past 24 hours 4 earthquakes in the past 7 days; 16 earthquakes in the past 30 days.
There are web sites where you can see about recent earthquakes. There are places that seem to have several very small ones every day.
 
While wind and tornadoes are definitely threats, our biggest threat is cold/snow. Our home is extensively insulted, well beyond the norm even for this area. We have insulating window film and thermal curtains, we have three heat sources (furnace, infrared electric, propane) and spare propane tanks, gasoline, and 2 generators, plus we have a basement bedroom designated as our stay warm room. That room has an insulated door, has spray in expanding insulation on every wall and the ceiling, has a safe-touch electric heater on a solar charging power supply, and has a large pile of wool blankets in the closet. Of course as residence of the great white North we have massive amounts of cold weather gear, cases of hand warmers, and so on. I recently bought a Fatso oven which could be incorporated into my plans if need be. I am confident we could stay home and survive an entire winter if necessary.
 
At our last place in AZ we had a 4.1 earthquake quite near us. I only knew about it because it was on the news. I never felt it at all. AZ does have a lot of small earthquakes.
The bulk of this state is of volcanic origin. There are many volcano craters. Yet I do not consider volcanoes a real threat here either.
 
You may also be in a place where seasonal heat could be problematic as well as seasonal flash floods.
Heat is not a problem here as the record high ever recorded at my location was in the low 90's.
While there is zero chance of flood problems at our place I never really thought about flooding taking out the roads leading to our place. That is a possibility. The closest highway which is the only real road around us could be taken out by flooding or a landslide/rock slide. When the only road that leads anywhere is taken out we would have no way to go any place until it was fixed, other than on foot or horseback. And I don't like riding horse though I could borrow one anytime from a neighbor, I'm sure.
 
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