[TowerTalk] R25 towers

[Jim Lux]

A call to your local building department will usually get the information 
about what sorts of "chemical anchors" they like to see.  Not that you 
actually will be getting a permit, or tell them what you're up to (you 
could say "patio cover" or something).  In our local area, they actually 
have a handout on this sort of thing.  You could also ask at a local 
building supply store that sells such things to contractors (they'll stock 
the ones that the city/county requires). I don't know that I'd ask at the 
local big box store, like Lowe's or Home Depot, since the person you talk 
to there may not be all that familiar with local regulatory requirements, 
policies, advice.

You could use any old all-thread and any old epoxy, but it doesn't cost 
much more to "do it right", and the chemical anchor kit comes with a nifty 
thing to squirt the adhesive into the hole, adhesive that is designed to be 
squirted into a concrete hole and anchor to a bolt.  The bolt quality will 
usually be better, too.  Easier to spin the nuts on, less likely to have a 
stress fracture somewhere when the stock clerk bent the all-thread putting 
it in the rack, etc. By the way, it's not all epoxy. They use acrylic and 
other chemical systems as well. All that good stuff...


Big companies like Hilti, Ramset, Unitex, Simpson Strong-Tie, and so forth 
all make these kits, and, by and large, they are available at the big box 
stores.

http://www.simpsonanchors.com/ has lots of info..figure out what you need, 
and go buy it.

Just for an example, for one of the products, from the charts there, it 
looks like 1/2" allthread (A 307 grade C), embedded 4 1/4 or 6 inches is 
limited by the allthread strength (3750 lbs). Going to A193, Grade B7 
all-thread makes the bond the limit at around 4500lbs (the allowable 
capacity of the bolt is 8080 lbs)

Going to bigger bolts and holes ups the strength a LOT.  1" bolts have 
allowable loads like 15,000 lbs.

Jim, W6RMK

At 01:21 PM 11/10/2003 -0500, K7LXC at aol.com wrote:
>In a message dated 11/10/03 10:03:03 AM Pacific Standard Time, k1my at msn.com
>writes:
>
> > I am putting up several 60 foot R25 towers and will be using the Rohn 25
> >  flat base. I would like to bolt the base plate to a concrete pad. What do
> >  you use? Threaded rod epoxyed into the pad? Expanding bolts?
>
>     Either one is FB. You'll need to rent either a roto-hammer or concrete
>corer to get into the concrete. Then either technique is a slamdunk. Your 
>local
>hardware store will probably have the all-thread and the epoxy and not the
>expansion bolts so the former would be easier.
>
>     There's not much stress in a small tower installation like this so you
>don't need anything exotic; i.e. special epoxy.
>
>Cheers,
>Steve    K7LXC
>TOWER TECH -
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