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The Texas Board of Insurance had an excellent book on building in hurricane prone areas … I don’t know if it’s still available. It covered things like roofing (six nails per shingle are recomended), hurricane clips, shear walls etc. It was the best single thing I’ve seen on the subject . If designed and built properly, the type of construction doesn’t make that much difference …..if a tornado occurs, all bets are off, and that little room may be the only thing that saves your life.
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The Texas Board of Insurance had an excellent book on building in hurricane prone areas ... I don't know if it's still available. It covered things like roofing (six nails per shingle are recomended), hurricane clips, shear walls etc. It was the best single thing I've seen on the subject . If designed and built properly, the type of construction doesn't make that much difference .....if a tornado occurs, all bets are off, and that little room may be the only thing that saves your life.
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Dan.
If you use concrete don't forget the rebar, concrete has high compressive strength but poor tensile strength. A grid of 5/8" rebar 2' o/c vertically and horizontally will make a big difference (the more the better). Keep the rebar close to the inside of the form as this would be the side under tension during severe wind loading. Vibrate the concrete or use plasticiser to get good consolidation (I would recommend the plasticiser for ICF's).
Keep roof overhangs to a minimum (they just catch the wind). Make sure the trusses (or rafters) are extremely well secured. Simpson Strong Tie makes many different types of tie downs for these and other structural applications.
I would also suggest using exterior grade plywood (glued and hand nailed with ring nails)for the roof sheathing. Pneumatic fasteners tend to be overdriven thus weakening the connection. If the shingles get blown off OSB swells, the nails pull through the surface of the OSB and the wind rips it off. Exterior grade plywood stands up much better under these conditions.
Good luck.
*Geez Albert,It's the short term memory that I have a problem with. Rebar is long engrained in my concrete fun and games.I'll definately be hand nailing everything as I can't drag my compressor all the way down to Tampa for such a small addition. And also when people want to help me I like to let 'em nail off the plywood. (Heh, heh, I once built a "Jam Hut" for my band to practice and record in. They all said they'd help and that they were pretty good at "hammering nails". I was worried about the oceans of sound waves vibrtating everything loose --our rythm section was over a quarter ton-- so I made them screw off the walls and roof. Every six inches! Heh, heh, heh)I'll use good plywood, glue it and nail with ring shanks.Fred, are you still there?"...And concrete walls would not do that much good without a concrete roof to tie the entire enclosure into a vault. "I had planned on a hurricane clip of sorts to tie the roof to the walls regardless of the wall material. I figured a PT plate bolted to the top of the ICFs, with the roof "clipped" to the plate.Maybe I'll figure the cost with int and ext plywood walls. What about this potential bug damage? How "potential" is it? Can't the ground be treated? Is it worse than plywood walls? How about flashing?As for ICFs, I've used them for foundations in Montana (no termites) and loved them. I'm not sold on them as a whole house system, but am curious to try them.Input appreciated,Dan
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Hi Dan,
You've probably finished designing and building, but for everyone's future referance, The Texas Department of Insurance's code for windstorm resistant construction is available online and is downloadable (acrobat--pdf) at:
http://www.tdi.state.tx.us/company/rswscode.html
Yeah, it's a code, but it might give you all some ideas.
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Muchas Gracias ave,
In fact, I'm still waiting for her to approve the floor plan.
Dan
*Dan,I live and work on the Alabama gulf coast and we have more than our share of hurricanes. Much of my work over the past year has been repair of damage from last years hurricane. One of the most important areas is the rafter to plate connection. there is a great deal of uplift on these connections so be sure to use some type of clip or strapping here. A great deal of damage comes from the loss of shingles and subsequent water damage so be sure to use nails not staples for the shingles. Plywood does seem to hold better than osb,but Ibelieve it is more a factor of propper installation(such as overdriven fasteners) than the materials. As for the walls, we use plywood on all corners for shear strength but if the roof stays on the walls are usually not a problem. Check FHB index, I have seen several articles on hangers and ties and straps with strength and uplift testing. Many of the codes have been updated and should give you a good idea what is necessary for that area.
*Charles,Re: roofing nails, 1 1/2" galvanized? Or is there a better choice? Strapping, ties = Yes.Thanks,Dan
*dan, we use 1 1/4 galv most of the time and they seem to outlast the shingles even right on the beachfront. im sure 1 1/2 would be fine maybe easier to hhold if handnailing. the most important part i think is not to overdrive if useing pnuematics. That is the big problem with staples, especially when working in hot weather.
*Will do. Thanks
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Ed,
Check Texas Tech University's Wind Research Lab homepage (www.wind.ttu.edu/). It should give you about all the info you might need for tornado and hurricane protection in a residence. It will have links to FEMA and other publications.
Gene B.
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I'm going to build a little addition for my sister and her kids in Tampa. Their house is concrete block with ugly stucco. I had planned to frame the addition, but recently thought about insulated concrete forms. Aside from being much faster, it seems like it might make a nicely safe place to hole up during thier many Hurricanes.
Does anyone have experience with Hurricane construction? In a recent issue of FH there was a little article about a hurricane proof room (located at interior of house) framed with 2x6 sheathed with 3/4" ply (both sides)and sheet metal (outside) bolted to slab.
Budget is a huge concern with this little addition, but I don't want to skimp on studs in a high hurricane zone.
Let's hear it: 2x4 vs 2x6 vs ICF's vs Moving out of Tampa.
Anyone know of suppliers of ICF's in Tampa?
I'll be upstairs drawing that addition,
Dan
*Dan,If I were building in any hurricane corridor, it would be with masonry or ICF's. Undersized windows and overbuilt shutters.
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Just a couple of thoughts - How about screwing the roof plywood down ? That would be better than nailing, I would assume.
As for nailing shingles - Wouldn't thicker plywood do a better job of holding the nail shank, and therefore hold the shingles on better ? Maybe just using more fasteners per shingle would be better.
I vaguely remember seeing pictures of a house down in Florida. They built a block wall, then poured a concrete "cap" of some sort along the top of it. There were anchors imbedded in the "cap" which had a U-channel for the trusses to sit in, and a long strap that went up and over the truss to hold it down.
I'm not sure, but I think they actually called the "cap" a "bond beam".