TV Antenna Mast: 2x4 Bolted To Outside Of Garden Shed?

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.
The Question:
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?
--
Pete Cresswell

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(PeteCresswell) wrote:

If this is a 2x4 framed plywood skinned shed you can install 2x6's (6" width against the outer skin) between the studs on the inside , attach your brackets to those . That might be difficult if there is wallboard or sheetrock on the inside . If that's the case , just rip a bevel on the top edge of your 2x4 so it sheds water .
--
Snag



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wrote:

put a membrane between them. This PT eats metal, or so they say. I would also seal up the joint with caulking (coat the material completely at the interface) That will keep the water out
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Hi Pete,

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
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Per HerHusband:

It's waaaaaaaay bigger that I expected - as in 32# and 7 x 11'.....
Accordingly, the mast will butt up on a cinder block on the ground.
Main thing, I want to be able to re-aim the antenna without climbing a ladder... but having it rest on the ground would also seem to alleviate a lot of stress on the W-brackets holding it to the side of the shed.
I think I will go with the 2x4 just for the spacing - to bring the bracket out to match to top one on the eve.
I like the washers... definitely going to do that.
--
Pete Cresswell

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Would something like a chain Vice Grip make a good handle to help turn the antenna? Harbor Freight sells a less expensive version.

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Per Dean Hoffman:

I have a couple of strap wrenches and expect (?) them to do the job.
I'll put a little PVC pipe sleeve in the top bracket so rotating does not score the mast and tighten the bracket just enough to prevent any side-to-side movement, but not enough to prevent rotation - although rotation will not be that easy.
Then I'll tighten the lower bracket enough to prevent rotation.
Might do the PVC thing too if I can still tighten enough to prevent spontaneous rotation.
Come re-aim time, I'll loosen the lower bracket use the strap wrenches to rotate to taste, and then re-tighten.
--
Pete Cresswell

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How tall (far off the ground ) is this antenna ?
Also how far above the roof of the bulding is it ?
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Per Ralph Mowery:

14', which puts it 3' above the roof of the garden shed.
I am pretty sure that will work, because my breadboard implementation has the antenna attached to an 11' pruning pole with the antenna just an inch or so off the roof.
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Pete Cresswell

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Just about anything should hold it up. I have had some ham antennas up without much suport. One was about that size and all I had was a pipe about 1 foot in the ground It stuck up about 4 feet and the main mast went down into that pipe. At the top of the house was a metal strap about 2 inches wide and a lag bolt on each side of that strap.
Sometimes you can over think things.
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Per Ralph Mowery:

Guilty as charged.... and not just sometimes.... -)
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On 10/2/2015 5:10 PM, (PeteCresswell) wrote:

Why not pour a small footer and set a 2-3" diameter pipe in that (i.e., something with a slightly larger ID than your mast's OD) and let the "ground" control lateral movement of that end of the mast?

Perhaps make the above mentioned 2-3" pipe even *longer* and *set* the mast inside it so the outer pipe carries *all* of the lateral mechanical load?

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It seems like you are doing plenty enough with what you propose, unless the antenna mast is a 40 foot tall mast with a humongous log-periodic antenna at the top. Don't overdo it!
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A pair of holes opposite each other, big enough you can put a Phillips screwdriver thru the pair of holes, will allow you to use the Phillips screwdriver to rotate the pole. Like I said yesterday, don't over engineer something so simple.
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