TT:
The idea of using non-galvanized metal as a bracket system
isn't very appealing. Wood can be painted to match the house,
and spreads the loads to prevent siding damage.
I have routinely made my house brackets from treated lumber,
and not used the Rohn bracket. Three reasons: The Rohn is
too flexible. The Rohn stands out from the house too far.
The Rohn doesn't spread the load across the structure enough.
None of my applications have had a deep-eave to clear; at worst,
just a 4" gutter plus facia. If I had an 18" eave...I'd build a
rohn bracket into my wood system.
I've used 2x8's, spread over 4' of siding, lag screwed into
the joists. If I need more standoff, I double the 2x8
and use longer lags. On each side, I add a piece of 2x6, which is
held by carriage bolts coming from the backside of the 2x8 tie.
Those bolts are long enough to also hold a 2x6, which passes
through the tower, to hold it in place.
So, side loads are captured by the 2x6's and transferred into
sheer loads on the carriage bolts. Pullout loads are captured
by a 2x6 in sheer, and transferred to tensile loads on the
carriage bolts and lags. Nice and solid. I've used it for 25g, 45g to 50',
and MA-40's.
A brief word on the fasteners: The lags are usually 1/2"x12".
YOU MUST DRILL PILOT HOLES. For a 4' tie-beam, I use six of these,
2 each in each of the 3 intersected joists. The Carriage bolts are
1/2", and have to pass through a sandwich of 3 or more 2x8's or 6's.
At 1.75 each, that's a minimum of 5.25". So 6" bolts are the minimum.
Use large flat washers with all bolts. Excess length is not a virtue;
you will bash knuckles.
This system requires some planning, and determining position of internal
wall, roof and floor truss structures, before tieing into them. If you
can thru-bolt with a back plate, rather than use lags, it's obviously
better, and easier.
Removal has proven zero damage to the siding, with three installs,
apart from the lag screw holes, which are easily filled and painted.
N2EA
Jim Jarvis, President
The Morse Group, LLC
732 548 5573 office
www.themorsegroup.net
results@themorsegroup.net
Strategic Planning and Success Strategies
for Sales Professionals and Entrepreneurs.
Sales Excellence Series beginning September 19, 2007
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|