In a message dated 12/8/2005 9:03:16 A.M. Pacific Standard Time,
towertalk-request@contesting.com writes:
jason@creager.com>
Subject: [TowerTalk] Rohn25G Rooftop Mounting
To: towertalk@contesting.com
Message-ID: <200512080806230876.1639674E@smtp.west.cox.net>
Content-Type: text/plain; charset="us-ascii"
Hi everyone,
I hope this doesn't "ramble" too much, but this turned into a kind of
"here's everything I know, what do you think?" post. The time has come for
me to "do something" with the three sections of 25G in my backyard. I have
two regular & one top section, the Guy Bracket with Torque Bars, and a Peak
Roof Mount PR25G. There isn't any information that I can find online about
doing this and the last time I contacted Rohn, they didn't have any info
they were willing to share about putting this on a residential roof. It was
previously installed like this, but with less forethought and design than I
am putting into it now.
I am a professional lighting technician and while I'm not a rigger, I've
taken two week long classes in rigging from Jay Glerum (THE man who wrote
THE book on theatrical rigging) so I am very familiar with doing things the
right way and looking for potential failure points. I also know quite a few
people who fly human beings professionally and know static/shock loading,
load distribution, safety factors, etc. inside and out. Through coworkers,
I have access to every kind of rigging equipment imaginable.
So, if I can't do this safely, I am not going to do it at all.
ROOF LOADING
What kind of reinforcement would I need across the joists in the attic for
that tower? Right now, I have a big ol' TH-7DX, but I would like to replace
it with a SteppIR eventually for better band coverage and less weight. I
have a decent amount of room since it would go in the center of the house
and a buddy with contractor accounts at the local steel and lumber places.
GUY WIRES
Since I have a rather small lot, I don't know if I have the room to run the
guys appropriately. I really don't trust the "anchor it to a cinderblock
wall" concept that I've seen a couple of times. Although, it was previously
installed with one loop of one of the guys *looped through a decorative
cinderblock* and held for 10+ years. The most common phrase in rigging
accident reports is "but we've done it a hundred times before".
What's the thought on anchoring guy wires to cinderblock? I do have a
rather large chimney structure (cinderblock with two clay pipes enclosed
with cement) that could be strap anchored.
What's an appropriate angle for the guy wires? They don't show guys for 30'
towers in the specs at
http://tinyurl.com/8lzbj (110MPH) Would this be considered a 29' tower or a
50' (approx) since it would be on top of the roof?
Can it be guyed to the roof if secured enough through the base?
Until I get those questions answered, I'm not sure if I can even put it up
there because I don't know where the guy anchors would have to be.
GROUND MOUNTING
Alternatively, I could get the Concrete Base Plate and mount it in the
corner of my L shaped house. Unfortunately, that's next to the pool and
about the only option I have for ground mounting since the sides of the
house are too close to the property line. The important code that I'm going
to follow is the one about "the antenna falling on your property".
SCREW THIS (and get a Glen Martin Roof Tower)
No guying required. Probably far less hassle than using what I have.
Definitely designed for the application. Heck, it's probably less hassle
than writing this email. :-)
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