[TowerTalk] : Nube rebar question

[edk0kl at centurytel.net]

I'm not sure tying the legs of a tower to a concrete base by putting
part of it in concrete. Most big towers taper down to a small point.
That point rests on some iron tied to the concrete. The guyed tower is a
moving load, putting the rotational or lateral force puts stress on the
base and could not be a good thing. Maybe I over think ...

In any event, rebar should never rest red brick, porous material transmitting
water to the iron. Same thing for "chairs" they inevitably attach to the 
iron, in time the rust keeps on going up the iron. "Chairs" are made
to keep the iron off the plywood form in a building or bridge molding
NOT on gravel, etc. Best thing is concrete block, same stuff the concrete
is. On my tower we suspended the foundation in the concrete with a 
horse on the ground over the form. The form is 10ft square using 2x4
and ordinary steel tie wire.

Don't forget to leave a drainage hole, slot, whatever for the condensation to
drain out of the leg.

Good Luck! We're all counting on you

73!

ed K0KL







----- Original Message -----
From: "Bill Aycock" <billaycock at mediacombb.net>
To: jbwolf at comcast.net, towertalk at contesting.com
Sent: Tuesday, December 16, 2014 6:59:10 PM
Subject: Re: [TowerTalk] : Nube rebar question

Jim-
Your terminology has confused me.  Can you describe what you mean by a "Roof 
Mount"?
Thanks--Bill--W4BSG

-----Original Message----- 
From: James Wolf
Sent: Tuesday, December 16, 2014 6:17 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] : Nube rebar question

Gentlemen,

I'm baffled that so many of us put part of a tower in the cement base when
installing a guyed tower.
I know I've said it here before, but on most guyed towers, why not use a
simple roof mount?  Put threaded rods in the cement that rise enough to bolt
to the roof mount so it won't turn or twist.

Reasons to consider this:

- No drainage to worry about in the tower section below ground level.
- Weep holes should be or can be made in the roof mount where they can be
easily inspected and cleaned out.
- You are not locked into changing to a different tower later in life -
assuming the cement base will handle it.
- You don't have to worry about getting the tower section in the cement
exactly vertical.
- For those who worry about lightning cracking the base, there would be a
lot less chance of it.  [maybe an old wives tale by now].
- It's probably less expensive.
- It's certainly simpler.

I installed my 120 ft. of Rohn 45 with a roof mount 25 years ago and I've
seen no issues.

Can anyone provide a good reason not use a roof mount for these
installations?   I would be very interested.

Jim - KR9U



___________________

On Tue,12/16/2014 9:27 AM, Kent Olsen wrote:
> What do you do in the bottom where the rebar sits on the dirt? Is this
just a sacrificial bit?

A layer of gravel at the bottom of the hole. If you put the bottom section
of the tower into the concrete pour as many of us do, the layer of gravel is
important for another reason -- it provides drainage for water that comes
down the legs of the tower.


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