Hi Pete,

I am going to make the breadboard TV antenna installation on my garden
shed permanent.
To that end, I will use two 4" standoff brackets to hold the mast:
- One up at the eve, so it will bolt into a frame member.
- The other a few feet off the ground. Seems pretty obvious that
the skin of the shed lacks the strength to support something like
that so I will bolt a 2x4 to the outside with bolts going trough
the skin into 3 of the vertical frame members inside the shed....
and then I'll attach the lower standoff bracket to the 2x4.

Are there any Good Practices for something like this?
I'm thinking in terms of the 2x4 up against the skin of
the shed and rot growing between the two as rainwater
seeps into the joint.

Something inside the shed instead of outside ?

# of lag bolts per vertical frame member? 1 centered
in the 2x4 or two spread apart?

If you have access to the inside of the shed, I would install some 2x6
backer boards between the studs where you plan to attach the brackets.
This will give you a secure mounting point without worrying about rot on
the outside of the shed.

If you need to install a 2x4 on the outside of the shed for some reason
(spacing to match the eave at the top, or no access to the studs inside),
I would treat it like a deck ledger. Cut the top of the 2x4 at a bevel so
water can run off easily. Then use a few washers between the 2x4 and the
shed where the lag bolts attach to the shed. This will allow space
between the 2x4 and the sheathing for moisture to run off and dry out.
Make sure the lag bolts are long enough to penetrate the blocking inside
the shed. It wouldn't hurt to caulk around the lag bolts where they
penetrate the wall.

Unless you are dealing with hurricane force winds or something, one lag
bolt per stud should be plenty. I'm guessing the brackets only have one
hole each side anyway.

If the antenna cable enters the building through the wall, make sure to
droop the cable down before it enters the building. This will allow any
water to drip off the bottom dip in the cable instead of running inside
the wall.

I don't know how big your antenna is, how tall your mast is, or if it
runs all the way to the ground. I have a five foot mast mounted at the
top of our gable end. It's simply lagged into the 5/8" plywood sheathing
with two brackets, haven't had any issues in 10+ years.

Good luck!

Anthony Watson
www.mountainsoftware.com
www.watsondiy.com