If in doubt, call a professional rigger. Yes it'll cost you some $$ but it beats the alternative if something fails and you plummet to the ground!

I've decided against removing the tower myself. Can you recommend someone who does tower removal & installation in the GTA?

yes, I agree, don't go past 10ft unsupported above the roof edge, and even at 10 ft you will worry about it, that's not worth it!


I have set up a temporary tubular mast pole for testing antennas which I made telescoping to about 10 ft above the roof and I would not leave it in the air unbraced, it sways a lot!

I still have to take the photos...

here is the prelim. temp. pole mast set-up...


http://s638.photobucket.com/albums/uu110/stanicet/mount/

after reviewing summarily all previous posts, I do not recall seeing the following idea, which a local installer suggested to me today...

He said he has installed masts right thru and out the peak of the roof, supported from inside the attic (onto the joists, & trusses), then sealed from outside. The balance of the equipment is then mounted onto the outside part of the mast, rotor, etc...

I thought he was joking at first, but no!

Sounds interesting, but worry for water infiltration at the base...

:D I thought I was the only one crazy enough to do this! BUT, it's worked now for 10 years, just a small leak a few months ago, but otherwise okay. I used 1-1/4" galvanized pipe, and ran the coax down the inside of it.

fmw63:

how did you seal it, why did it leak, how difficult is it to access the roof if you modify, and can you post photos of the set up here or in photobucket...


Also, where does you pipe come in, did you drop it to the inside of the house...


thanks

I would be very leery about having the mast go through the roof. As wind waves the antenna, it will gradually enlarge the hole and disturb whatever you use to seal around the hole. This is especially true if you have plywood or particle board sheathing.

Vents, stacks, chimneys and other things that normally go through the roof don't catch much wind and won't put as much pressure on the hole. Bolts for tripods should go into a truss or rafter (or at minimum a large solid piece of wood) and should be torqued enough to prevent any movement.

I would be very leery about having the mast go through the roof. As wind waves the antenna, it will gradually enlarge the hole and disturb whatever you use to seal around the hole. This is especially true if you have plywood or particle board sheathing.

Vents, stacks, chimneys and other things that normally go through the roof don't catch much wind and won't put as much pressure on the hole. Bolts for tripods should go into a truss or rafter (or at minimum a large solid piece of wood) and should be torqued enough to prevent any movement.

Vents, stacks, etc. usually have a larger hole than their diameter because the roof is slanted and have a flashing to seal around the hole. Plumbing vents use a rubber one. I wonder if they make one of those to fit a 1 1/2" mast.

I am still considering this alternative to a chimney mount. I was even considering a way to motorize raising and lowering the antenna mast. When a lightning storm approaches or it's extremely windy I could lower the antenna. I'm sure that would win some "geek points" with my neighbors too :rolleyes:

I still maintain that erecting a tower is cheaper and easier.

My concern with pushing a mast through the roof (besides the obvious leaking concerns) is that you introduce the possibility of attracting lightning into your home. With a tower, most of the energy from lightning is kept outside.

roger1818:

I can tell you based on my experience with masts, if you have any mast moving at all at its base, you have a problem and incorrect bracing...

first you need a steel sleeve anchored properly at the highest point, on the joist, just under the roof topping, this should never budge! if done properly...

techluvr:

that's what I made, 2 aluminum pipes one in the other, light, strong, cheap, rotating, telescoping, all you need...


I posted the pics... I raise it, lower it, any height, turn it by hand, all easy, I can even change the antenna from my window...the next step is to put it thru the roof, and into a room cupboard ...


No difference for lighting, that's all BS, just ground it properly like all the others should be...

Jase88:

Jase88: if you have over 500$ to spend on a tower, have the space, and dont mind the headaches and costs of potential modification etc, then go fo it!

I still maintain that erecting a tower is cheaper and easier.

My concern with pushing a mast through the roof (besides the obvious leaking concerns) is that you introduce the possibility of attracting lightning into your home. With a tower, most of the energy from lightning is kept outside.

Sometimes there's aesthetics reasons for not wanting a gangly looking steel tower next to your home. After paying 10's of K$ for interlocking stone paving around the house there's no way I'm ripping it up to erect a tower. Especially when I'm not sure I'll pull in any more than the local stations that I can already get with a coat hanger in the attic. When I lived 'in the wilderness' I had a 50' tower; I couldn't get any stations without that. Now I'm in the big city ;)

I can tell you based on my experience with masts, if you have any mast moving at all at its base, you have a problem and incorrect bracing...

So you are suggesting that you brace the mast above the roof using a tripod or guy wires? If you do that, I agree that it shouldn't put much pressure on the sheathing, but then I am not sure what you are gaining by going through the roof.

first you need a steel sleeve anchored properly at the highest point, on the joist, just under the roof topping, this should never budge! if done properly...

Below the sleeve, the mast won't move, but above the sleeve it will (although if the sleeve is just under the roof the amount of movement at the roof line will be small) so IMHO the support needs to be above the roof.

In my mind, I just don't see any huge advantages of putting the mast through the roof, and the potential for leaks would make me lean towards other solutions.

@balm: I just bought a used 80' freestanding tower in excellent condition with all the hardware for under $175US. I just need to buy the concrete, and spend a Saturday putting it up.

Obviously a tower isn't for everyone. But in terms of potential cost, it's the option I believe should be considered first.

With regards to grounding a "roof-inserted mast": How do you propose to ground the mast? What gauge of wire would you use?

Vents, stacks, etc. usually have a larger hole than their diameter because the roof is slanted and have a flashing to seal around the hole. Plumbing vents use a rubber one. I wonder if they make one of those to fit a 1 1/2" mast.Physics tells us that apart from bearing the weight load downwards, the point of greatest strain on an antenna mast that is not free-standing is at its highest point of bracing. A free-standing mast that has no bracing or guy wires has all its points of strain occurring down where it leaves the concrete. For that reason, manufacturers make free-stading masts very stout. A non-free-standing mast that is braced by a bracket onto a roof end joist will have its maximum strain at that joist bracket. In the case of an antenna through a hole in the roof its greatest point of strain and wear would be at the collar where it pops through the roof. Even if you put a flexible donut there rather than a solid brace the point of maximum strain will still be only just below it where the mast is braced inside the attic, meaning that the donut will still be forced to deal with all vibration, keeping in mind that the greatest mass on the whole mast is at the upper end point!

For a very Canadian example, hold a hockey stick above your head. No big deal, right? Now tape your skates onto the blade of the hockey stick and hold it above your head again. Notice that while the weight of the stick is on your lower hand, the strain of keeping it straight upwards is on your upper hand. That is the same with antenna mount bracing points. That's the whole purpose for how tripods work, with the pole taking the weight but the tripod legs working against any strain.

I do not recommend vent stack mounts or hole-cuts in a roof. As roger1818 summarized, an antenna above the roof is often in a dynamic state, even if we cannot notice this with our eyes. Also keep in mind that snow/ice load on the roof itself causes flex upon it, again maybe not noticeable to the eye. Any roof punctures, such as that for a lag bolt on a tripod leg going through to a roof joist, need to be sized only for the bolt's diameter and then liberally coated with roofing tar when the bolt is sunk all the way into the joist.

On the West (Wet) Coast the potential for water damage from using vent stacks or other such hole-in-the-roof mount points is way too high.

Jase88:

What about transport, shipping, and the exchange.

That's great, you are obviously a "handy man"... I'm curious what is the method for installing the 80 ft tower, is it in sections, how do you lift...what is the hardware needed...

also have you estimated what your time would be worth if hired and what equipment, (how many man-hours - I assume you are not attempting this alone!)

Also I'm curious where you are, situation, etc to need the 80 ft, that's some great hieght!


Re. grounding...there is a whole thread on that subject...that bridge can be crossed when I get to it...

roger1818:

I'm working on a sketch...to see if feasible

I do not recommend vent stack mounts or hole-cuts in a roof. As roger1818 summarized, an antenna above the roof is often in a dynamic state, even if we cannot notice this with our eyes

I was toying with the idea of a galv. steel pipe secured firmly to the roof trusses for several feet below the roof line; it would protrude only about a foot above the roof line and be sealed from leaking ( hopefully successfully ) with roof tar and flashing. A slightly smaller diameter pipe is inserted into this outer sleeve and is the actual antenna mast. It can be raised and lowered or rotated freely from inside the house. A piece of sump hose securely clamped to the mast could extend to below the point where the mast enters the secured pipe for waterproofing that opening. The sump hose accordions as the mast is raised and lowered.

The advantage for me in this set-up is that if I put it in the attached garage I'm not so concerned about the occasional water dripping on the car. It would be directly above the main house ground; I could run a ground wire down the inside garage wall with ceramic stand-offs.

This is all very scary when considering the consequences of a botched installation. My biggest concern is that in the end I would be no better off than I am now. I have climbed up on the roof with a CM4228HD and a laptop but was not able to pick up any distant (US) stations; only the two local ( 30Km and 5Km away ) broadcast towers.

I'm seriously considering just to hang the antenna in the garage rafters and call it a day.

For a very Canadian example, hold a hockey stick above your head. No big deal, right? Now tape your skates onto the blade of the hockey stick and hold it above your head again. Notice that while the weight of the stick is on your lower hand, the strain of keeping it straight upwards is on your upper hand.

Great example stampeder. Another example is to take the hockey stick and get down on your hands and knees and hold the but end of the stick on the ground with one hand and using the other hand about 30cm above the ground try and hold the stick upright. Now get a friend try to push the stick over at the blade. Even the slightest push will be almost impossible to resist. That is the effect wind on your antenna will have on the upper brace. Even if you do manage to hold it still, the stick will start to flex just above your upper hand. If your brace is below the roofline the mast will flex inside your roof. This flexing will gradually wear on whatever you use to seal the hole. If you do a good job it may not leak this year or next year, but it will eventually leak and once it starts to leak, the leaks will only get worse. Even if it lasts 10 years, that isn't good enough for me as the problems that result from leaks (mold and mildew) can be very expensive to fix.

see my prelim rough sketch here :

http://s638.photobucket.com/albums/uu110/stanicet/roof/?action=view&current=roof.png

this offers many advantage:

1- much stronger than any on top of roof mount
2- much easier to install
3- much faster to install
4-much harder to make mistakes
5-much safer
6-much cheaper
7-much more flexibility (options)
8-can protect indoor rotator, can be made telescopic to drop/raise, can protect amps, (although farther from antenna), can even drop into house
9-easier to take advantage of max house ht

10-no different in terms of the physics than a side wall mounted mast!