[TowerTalk] how much tower can you put on a roof

["FireBrick" <w9ol@billnjudy.com>]

As a retired Chicago licensed contractor I have a bit of experience in this.
First off
You can't equate the dead load capability of a roof to the sq foot of an 
antenna.

I'll give an example.
In Chicago area, roof designs are determined by their type and pitch.
A normal residential roof is designed to withstand approx 20 to 25 PSI.
That's 20# exerted on EVERY square inch.
(it's been a few years and requirements may have changed)

Another design criteria is pitch, flat roof will accumulate more snow than a 
pitched roof.
A steep pitches will accumulate even less.

In past years, they built steep roofs so they could utilize smaller dimensional lumber.

Traditional rafter/joist are now replaced with truss construction.

So it's not how much weight you are putting on the roof before it falls in.
But how much stresses in vectors it can handle before it lifts up.

Only recently have they begun to anchor roof joist, rafters, and trusses to the walls with 
metal brackets to keep them from peeling up in high winds.


So basically, after all that crap. I would get a pro. A carpenter to look at your roof 
from the inside and determine what kind of attachment is needed to SPREAD the loads 
around.
For both the tower base and any guy anchors which may needed.

Roof mount is great, if installed correctly
good luck


-----------------------------------------------------
"The less time planning, the more time programming.
-----------------------------------------------------

Bill H. in Chicagoland


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