I'm considering mounting the tower on my deck which is made from 2" x 6" decking with 2" x 8" rafters on 24" centers.
<snip> Does this sound feasible or am I gambling?
Rod -
Let me ask you two+ questions:
1. Is this configuration included in any installation guidance issued by Rohn? 2. Are you required to get a building permit? If so, what documentation are you required to provide in terms of plans, engineering drawings, and loads analysis?
If the answer to #1 is yes, then you're in the clear. Follow Rohn's directions and you're fine.
If the answer to #1 is no, and #2 is yes, you might find that you may have to provide details that would PROVE that your installation is safe. (This is in contrast to an installation that exactly matches a recommended Rohn configuration, where you could reuse their canned analysis for permit purposes.) And unless you are a professional engineer (or you know one who will work pro bono), your savings of two sections of tower may pale in comparison to the cost of a PE's time to do the required analysis.
And even if the answer to both questions is no, it would probably STILL be a good idea to get someone knowledgeable to review the analysis and see if it makes sense. You might find someone on this list that could do that, but I'm not sure I'd "gamble" (your word) my house on a guess or back-of-the-envelope calculation.
Good luck.
73, Steve W3HF
P.S. I'm NOT a mechanical engineer. But I did take mechanics classes when I got my EE degree 28 years ago, and I did pass the first half of the NY state PE exam back then. And I personally don't think that 2x6 decking on 24" centers would be enough to safely mount the base of a 20-30 foot tower made of Rohn 45G. After all, any lateral loads would be braced by only a few 16d nails or 3" screws, the ones that hold the decking to the joists. (They're called rafters in a roof, but joists in a floor.) But I have NOT done the calculations, and would welcome the inputs of someone who is more qualified to analyze this.
Steve,
Thanks for the reply. Well, I guess the point is now moot since my wife overruled putting on the deck. I have been talking about this with her for about 6 months and she just now said it would prevent her from putting a roof over the deck to make it a 3 season deck..Argggg
I told her I could ground mount it at the end of the deck but it will require more expensive 7/8" hardline due to the distance. Guess that's the way I will be going now.
Thanks to all for the comments and suggestions.
RoD KD0XX
P.S. Floor joists was the word I was looking for but couldn't get it out of my brain :-) At any rate, they could be called rafters OR joists since my back door exit's right under the deck. It depends if your under or on top of it. hihi
Thanks again.
A good friend will come and bail you out of jail, A TRUE friend will be sitting next to you saying.....
"DAMN THAT WAS FUN"
-----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of [email protected] Sent: Sunday, May 13, 2007 9:44 PM To: [email protected] Subject: [amsat-bb] Re: Tower suggestions....
I'm considering mounting the tower on my deck which is made from 2" x 6" decking with 2" x 8" rafters on 24" centers.
<snip> Does this sound feasible or am I gambling?
Rod -
Let me ask you two+ questions:
- Is this configuration included in any installation guidance
issued by Rohn? 2. Are you required to get a building permit? If so, what documentation are you required to provide in terms of plans, engineering drawings, and loads analysis?
If the answer to #1 is yes, then you're in the clear. Follow Rohn's directions and you're fine.
If the answer to #1 is no, and #2 is yes, you might find that you may have to provide details that would PROVE that your installation is safe. (This is in contrast to an installation that exactly matches a recommended Rohn configuration, where you could reuse their canned analysis for permit purposes.) And unless you are a professional engineer (or you know one who will work pro bono), your savings of two sections of tower may pale in comparison to the cost of a PE's time to do the required analysis.
And even if the answer to both questions is no, it would probably STILL be a good idea to get someone knowledgeable to review the analysis and see if it makes sense. You might find someone on this list that could do that, but I'm not sure I'd "gamble" (your word) my house on a guess or back-of-the-envelope calculation.
Good luck.
73, Steve W3HF
P.S. I'm NOT a mechanical engineer. But I did take mechanics classes when I got my EE degree 28 years ago, and I did pass the first half of the NY state PE exam back then. And I personally don't think that 2x6 decking on 24" centers would be enough to safely mount the base of a 20-30 foot tower made of Rohn 45G. After all, any lateral loads would be braced by only a few 16d nails or 3" screws, the ones that hold the decking to the joists. (They're called rafters in a roof, but joists in a floor.) But I have NOT done the calculations, and would welcome the inputs of someone who is more qualified to analyze this.
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