Mounting a mast to an external wall

[jonzilla]

Hello all, I have a question about mounting a mast to an external wall. I would like to use a 10' length of 1.25" EMT, and attach it to an exterior wall using 8-inch standoff "Y" brackets. I would end up with about seven feet of mast over the peak of the roof, with three feet of the mast supported by the two brackets.

My question is if standoff brackets such as these are suitable to support the full weight of a 10' mast, or would I instead need to use a longer mast, attached to/supported by the ground, and just use the standoff brackets as an additional support to keep the mast a constant distance from the wall.

Thanks for any suggestions.

 

[mrweather]

What kind of antenna are you planning to mount on the mast? EMT is pretty heavy stuff and the standoffs may not be able to support the vertical weight of both the mast and antenna.

 

[QDP2012]

Welcome to RR,

If you haven't already considered it, when selecting brackets and number of brackets, you might want to consider not just the antenna/mast vertical weight, but also the effect of wind from each direction -- whether wind would try to pull the antenna/mast away from the structure, or whether it would try to blow the antenna side-to-side and rotate it down along the wall-face.

A longer mast, with more length below roofline than above roofline, with more than 2 mounts/stand-offs would certainly be more stable. Are you planning to run grounding-cable to the ground? If so, it might be easier to have the mast reach the ground too.

Hope this helps,

 

[jonzilla]

What kind of antenna are you planning to mount on the mast? EMT is pretty heavy stuff and the standoffs may not be able to support the vertical weight of both the mast and antenna.

Hi, right now I'm thinking a J-pole for two meter is going to be about as heavy as I might get.

Welcome to RR,

If you haven't already considered it, when selecting brackets and number of brackets, you might want to consider not just the antenna/mast vertical weight, but also the effect of wind from each direction -- whether wind would try to pull the antenna/mast away from the structure, or whether it would try to blow the antenna side-to-side and rotate it down along the wall-face.

A longer mast, with more length below roofline than above roofline, with more than 2 mounts/stand-offs would certainly be more stable. Are you planning to run grounding-cable to the ground? If so, it might be easier to have the mast reach the ground too.

Hope this helps,

Thanks, I will be grounding the mast and antenna, so this is a good consideration.

 

[profiledescent]

Add a triangular truss at the bottom to support the downward weight, and you should be good to go.

 

[jonzilla]

Add a triangular truss at the bottom to support the downward weight, and you should be good to go.

You mean like a cantilever at the bottom? That's a great idea, thanks!

 

[RC286]

I made a mast out of 1 1/4" EMT it is attached to my fence.
Been up for about 1yr now and nothing has budged or come loose.

https://www.youtube.com/watch?v=7KG1PJ23vHk
There is a video of it. The antenna is actually larger than the mast. It has stood up to 90kmh gusts of wind.

It might give ya some ideas.

 

[jonzilla]

Nice setup RC, thanks for the link; I'm glad to know the 1.25 EMT is able to stand up to the weather!

 

[milkman21218]

A very nice install.