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[TowerTalk] Guy Wire Tension and Chimneys

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Subject: [TowerTalk] Guy Wire Tension and Chimneys
From: (Guy Olinger, K2AV)
Date: Tue, 14 Sep 1999 17:06:16 GMT

GUARANTEED to destroy both tower and chimneys in a big windstorm, and
probably do a lot of damage to the roof below. Chimneys are designed
to set on their own weight, vertical. That's why you can get away with
constructing them with bricks. Mortar between the bricks stands up
against vertical compression, but has only FRICTION resistance against
horizontal shear forces. 

That is enough for the chimney itself, because wind forces are SPREAD
OUT over all the chimney, more or less equally spread over all the
courses of brick.

The guys will CONCENTRATE all the wind force against the tower and
create a horizontal shear force against the first course of mortar
under the guy points, many times what the bricks normally experience.

EVEN IF IT DOESN'T pull the chimney over on the roof, it can create
cracks in the flue tiles, or where they join, which is a major
contributor to chimney fires that can spread to the house. Wait until
your insurance company discovers that you guyed a tower to a chimney
that had a fire... Or think about someone that buys your house later
with hidden damage of this sort.

If this is not compelling, call your local building inspector and let
him elaborate.

On 14 Sep 99 09:07:53 PDT, you wrote:

>Bill Jones (WA2HYA)
>I am putting up a 50 foot Rohn 25G tower and want to guy the tower to a
>chimney in two of the three guy points.  Does anyone have any experience with
>guying to chimneys?  Each chimney is 3' by 2 1/2' and in excellent condition. 
>What thickness of strap should be used around the chimney?  Each would have
>two guys attached according to the Rohn catalog - each guy with an initial
>tension of 400#.   Also what is the best way to measure the tension of the guy
>wire? Thanks in advance.
>Get your own FREE, personal Netscape WebMail account today at 

73, Guy
--. .-..

Guy Olinger, K2AV
Apex, NC, USA

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