[TowerTalk] Rebar Cage and J-Bolts

Steven H Sawyers (na0ia) sawyers at inav.net
Sun May 4 14:51:18 EDT 2003

My comments/advise below:

At 01:18 PM 5/4/2003, Jerry K3BZ wrote:
>I'm putting in a base for a used tower, and I can't get exact base specs
>from the manufacturer (Heights).  It's an "old-style" Heights tower, and
>Heights apparently only wants to provide base specs when you buy all the the
>base hardware, and then the specs are for the "new style" anyway.  So, I'm
>planning to install an over-sized base in order to cover all contingencies.
>I understand I'm supposed to wire the elements of the rebar cage together,
>as opposed to welding them, I hope that I have that correct ?

Yes - you can get wire ties that have Loops on each end of various lengths 
from a rebar
supplier other than the "Home Depots" of the world. Usually come in large 
rolls of 5 or 10 thousand. I bought a roll 20 years ago for a garage I was 
doing and have no doubt they will out last me. I go 6" long and take 2 
wraps around the two rebar before I start twisting. You will also want to 
get a hooked spinner tool for about $5. Makes things go much faster and
the tool works great for pulling springs off inside of car or truck drum 

>Also, are the J-bolts supposed to be wired to the rebar cage?  It doesn't
>seem feasible, because the locations of the vertical sections of the J-bolts
>won't exactly touch the rebar cage... so, are the J-bolts simply suspended
>in the concrete?

The J bolts, and all rebar for that matter, need to be at least 3" away 
from any dirt or form so the rebar or J bolts are fully encased in 
concrete. The J bolts can be just suspended in the concrete. If they are 
short - 18" for Rohn base plates on guyed towers - I just stick them in 
after the concrete is formed and struck, but before I trowel it off. I 
usually have to jiggle them up and down to move them around.

For long ones I have wired or tack welded spacers on the bottom to keep the 
spacing and geometry right while pouring the concrete. Wiring is better - 
no heat effected zone in the metal - but welded is more secure and less 
likely to slip.

>Also, the J-bolts I got from Heights are just over 5 feet long... is it OK
>to have the bottom curves of the "J's" sitting on the base of the 5-foot
>deep hole hole?  Or should I dig deeper to fully encase the J-bottoms in the

Dig it deeper.

>Help will be appreciated.
>Jerry K3BZ

73 de na0ia

>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
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