Not sure why i can’t do anything after i pasted in that link. had to submit and start over couldn’t even edit it. Did something wrong 🙂
That is a link with the safe room requirments. and the next will be building codes which doesn’t have much in for tornado other than wind speeds. That would be under chapter 3 which is building planning then go to storm shelters and then click on the different stuff like wind load ETC.
But as for further codes and recommendation you have to talk with every township for the actual requirements to see how hard it needs to be tied down . I never did a house in Kansas but the people i work with did one about a year ago. Some townships have a PDF with the requirements but sorry i don’t have one of those.
Oklahoma seems to be pretty popular with tornadoes so I had a quick browse.
In Oklahoma, Table R602.3(1), item 6, Rafter or roof truss to plate . . .
Does that mean no matter what the truss is spanning (20′, 40′ or even 60′) all that’s required to tie that truss down is 2x 3.5″ nails skewed in from 1 side and another 3.5″ nail skewed in from the other side?
Would 24″ centres be typical truss spacing there?
All our tie-down is governed by the area being held down (in square metres) multiplied by the uplift pressure in kPa Stratco has a design guide to help determine the relevant uplift pressure. All Aussie roofing manufacturers have similar guides.The type of fixing is also determined by the Joint Group rating of the top plate and truss timber (the weaker of the two)
Yeah it looks like it. but that wouldn’t work most places because most township make you use special Truss or rafter hangers to fasten them and those i hear are really tied down. But something to keep in mind almost all truss companies send there own fasteners along we use the Simpson H2.5 Clips or a hurricane tie-down strap (pic below is the H2.5 clips) So I’m guessing they use they use something similar.
Yes trusses are always @ 24″ O.C.
Thanks for sharing that Stratco design guide. Want to check it out more later when i have time.