In a message dated 8/18/03 8:18:50 PM Pacific Daylight Time,
> I thought that I had a current Rohn catalog, but it turns out to be
> around 1997 vintage. Great.
Actually the drawings haven't changed in years (decades in most cases!)
so a 1997 version is current.
> I am in the process of installing a Rohn 25G bracketed tower of about 60
> feet. It will be bracketed against my house at around 23 and again at
> 43 feet (yes, I have a tall house).
> However, the base section concerns me. I purchased a short base section
> (SB25G) which is 3'4" and was going to use this as my base section. Is
> this a problem? I didn't have a drawing for it, so I used drawing
> number A871298r1 and modified it for the short section instead of the
> five foot section. That means instead of the hole being 4 feet deep,
> it is 36 inches deep, including the 6 inches of gravel for the drainage.
> The soil is solid georgia clay.
> I was all set to pour concrete today...have the tower plumbed (I think)
> and leveled and decided I'd better check with someone who knows. Has
> anyone used this setup before?
The aforementioned drawing is for a drilled pier but reflects the other
configurations; i.e. 4-foot deep hole.
Is a 3-foot hole a problem? No. The purpose of the base of a guyed or
housebracketed tower is to keep the tower from sinking in the ground. With your
relatively small tower and subsequent relatively small tower/wind forces, it's
not going to exert enough downward compression force on the base to worry
The tower specs fall into the "one-size-fits-all" plus a good-sized
safety fudge factor. In other words they use the same base spec for towers up
190' so you can see the spec is pretty much overkill for a 60-footer.
Also it's interesting that they specify a 4-foot hole and the short base
is only 3' long - hi.
GL on your new installation.
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