[TowerTalk] Rooftop guy anchoring

[John Parnell]

Hello!

 

This is my first post to this list; my apologies for the lonnng post
 I am
building a tower for myself the first time in 23 years.  I have worked for
my friend Steve, K7LXC/Towertech helping with many of his installations over
the years. I have done quite a bit of research at the Rohn site and found
some excellent resources here on the web ; I am eagerly awaiting the arrival
of Steve’s tower book


 

I have one nagging question that I am having a hard time answering, I
attempted to search the archives here and the www in general, but could not
spot anything that related to this issue. 

 

My installation is a simple one:  40 ft of Rohn 25G ;  it will have a yard
of concrete for a base covering the bottom four feet of tower. It will go up
THROUGH an existing deck at five feet- I will bolt it to a header I will
install as it goes through the deck.  I will also have a Rohn house bracket
installed at the 15ft level , with a sturdy backup structure (as per K1KP &
N1CQ’s excellent QST article of 8/96). There will be a five foot mast
holding an ancient Wilson SY33 yagi (TA33 clone)with 5.9 sq ft wind load.
>From what I can tell from the Rohn specs, I will still need to guy the tower
since it will have aprox 21 ft of structure above the bracket.  

 

My question concerns guy anchors: 

 

My fiancé says it would be fine to guy to the roof but NOT out into her yard
to anchor guys to the ground in her nicely landscaped yard. There is plenty
of room to mount guys on the roof 32 ft back from the tower in 3 places ( I
am foggy on this point, I am not sure if I should calculate the height of
the tower from the bracket or base for guying purposes; I could do either) 

 

My problem is that I need to know the best way to anchor the guys to the
roof. My guess is that the  best way would be to put a large diameter eye
bolt down through the roof to the top plate of the wall at a corner, or -
next to an intersecting interior wall and through-bolt it with a nuts and
washers (or a flat bar). This would be a BIG problem in that I would have to
dig through a lath and plaster wall
it would be ugly. What I would LIKE to
do is place a piece of heavy angle iron (3x3x1/4?) UNDER the rafter tails of
the eaves just outboard of the wall. I would then run the eye bolt through
the roof and and secure it under the center point of the angle. I could
further beef this up by crawling into the attic and bracing the affected
rafters to the ceiling joists below.  I could also anchor it to the peak of
the roof by adding a bit of backup structure. 

 

Complicating this is the need to get a city permit for the installation;
whatever  I come up with needs to be kosher with an engineer; Has anyone
here had experience with roof mounted guy anchors that have passed muster
with a professional engineer?  Any ideas/suggestions greatly appreciated. I
am a former welder/steel fabricator with a welding machine and could make
what I need add structure where needed. Also, if any of you are in the
Seattle area and know of a Ham-friendly prof. engineers, email me off-list. 

 

Thanks!

 

-John, K7HV