How do you make a roof mount leakproof? (4 Viewers)

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tsbarker13

Thread Starter
Active SatelliteGuys Member
Dec 1, 2009
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Virginia, USA
I am looking at installing a Slimline 5 at my house, and about the best location I can find would be to mount it on the surface of the A frame roof (atop the shingles). My question is, what is the best technique to mount it and be sure that it won't create any leak point(s) where I install it? I figure I will have the roof mount and the two support stabilizing arms to actually penetrate the roof.

Also, should I use like carriage bolts and go into the attic the put bolts on the inside, or is wood screws sufficient?
 

talos4

SatelliteGuys Pro
May 26, 2005
577
0
SE Wisconsin
Welcome to the forum!

Lag screws into the framing studs esp for the main pole mount. It's not always possible to hit studs when mounting the support arms.

As far as a sealant use what's designed for roofing. Roof Cement.

Drill pilot holes through the shingles and into the deck/studs. Put a layer (1/8-14" thick) of roof cement over the holes (directly on the shingles) and overlap that area approximately 1/2-1" larger than the bracket. Use a trowel to spread the cement. Install the mounts. When you press the mounts into place you should have cement oozing through the holes and out from under the bracket.

I would recommend an additional covering of cement over the screw heads and around each bracket.

Roof cement is available in standard caulk tubes and you shouldn't need more than one.

The roof cement will bond with the asphalt in the shingles and give you a good leak proof install. Silicone sits on top of the granules and will not bond to the asphalt in the shingles.

It's a bit of a rant of mine, silicone should never be used on asphalt shingles. Nearly 20 years in commercial roofing hasn't changed my mind.

Good Luck
 

wildbill129

SatelliteGuys Pro
Jul 31, 2009
1,273
0
Redding, CA
If it was my house, and I was doing it myself, I would buy a Commdeck mount. It's a much better way of mounting dishes....only the monopoles (not shown in the pic) would have to go through the shingles. Less chance of leaks...

CommDeck Satellite Dish Mounting System - Smarthome



 

yorktown

SatelliteGuys Pro
Nov 10, 2009
513
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General Location
It's a bit of a rant of mine, silicone should never be used on asphalt shingles. Nearly 20 years in commercial roofing hasn't changed my mind.

Good Luck

I've used silicone sealant on asphalt shingles every time I've put up my dish and dishes for friends with no problems ever. Nearly 13 years in installing my dishes hasn't changed my mind.
 

raoul5788

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Dec 28, 2004
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Welcome to the forum!

Lag screws into the framing studs esp for the main pole mount. It's not always possible to hit studs when mounting the support arms.

As far as a sealant use what's designed for roofing. Roof Cement.

Drill pilot holes through the shingles and into the deck/studs. Put a layer (1/8-14" thick) of roof cement over the holes (directly on the shingles) and overlap that area approximately 1/2-1" larger than the bracket. Use a trowel to spread the cement. Install the mounts. When you press the mounts into place you should have cement oozing through the holes and out from under the bracket.

I would recommend an additional covering of cement over the screw heads and around each bracket.

Roof cement is available in standard caulk tubes and you shouldn't need more than one.

The roof cement will bond with the asphalt in the shingles and give you a good leak proof install. Silicone sits on top of the granules and will not bond to the asphalt in the shingles.

It's a bit of a rant of mine, silicone should never be used on asphalt shingles. Nearly 20 years in commercial roofing hasn't changed my mind.

Good Luck

Why do you not use silicone on asphalt shingles?
 

cfb

SatelliteGuys Pro
Apr 10, 2009
1,492
1
California
I think the principal problem is that silicone wont adhere well to asphalt, and asphalt expands and contracts while silicone really doesnt. So over time, you'll have a gap between the silicone and the shingle. Still might not leak much, but its not optimal. For sealing a hole through the roof, silicone to the wood sheeting provides good adherence and there isnt much difference in their expansion/contraction rates. Roofing cement will liquefy a bit during the summer and seal any cracking from movement while silicone will remain rigid and is subject to cracking.

If this all happens on a part of the roof that see's quite a bit of runoff, you might have a problem. But then again it takes quite a while for enough water to build up in the attic deck insulation for it to seep to and through to the sheetrock, so it might take a while and a good long rain to notice.

Now I might have to again break out the story of my friend who used to get drunk, take off his pants, put them over his head and run through traffic. Never got hit by a car. But that didnt make it a good idea.

I guess if he did get hit, it wouldnt be his fault. Or the drivers fault. It'd be the asphalt.
 

yorktown

SatelliteGuys Pro
Nov 10, 2009
513
0
General Location
I think the principal problem is that silicone wont adhere well to asphalt, and asphalt expands and contracts while silicone really doesnt.

I think the principle use for outdoor silicone is sealing up around windows and door frames. It's made to expand and contract as it get's warmer and colder outside. I've never had any problems with silicone on the shingles cracking and causing gaps.

There's nothing wrong with using silicone on a roof.
It's not like running out into traffic with your pants on your head.
 

jckm78

SatelliteGuys Guru
Apr 21, 2006
136
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I use tar patches or pitch patches, to sealed the lags. Yeap, use this or roof cement is optimal.
 

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raoul5788

Studebaker driver
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Dec 28, 2004
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I think the principal problem is that silicone wont adhere well to asphalt, and asphalt expands and contracts while silicone really doesnt. So over time, you'll have a gap between the silicone and the shingle. Still might not leak much, but its not optimal. For sealing a hole through the roof, silicone to the wood sheeting provides good adherence and there isnt much difference in their expansion/contraction rates. Roofing cement will liquefy a bit during the summer and seal any cracking from movement while silicone will remain rigid and is subject to cracking.

If this all happens on a part of the roof that see's quite a bit of runoff, you might have a problem. But then again it takes quite a while for enough water to build up in the attic deck insulation for it to seep to and through to the sheetrock, so it might take a while and a good long rain to notice.

Now I might have to again break out the story of my friend who used to get drunk, take off his pants, put them over his head and run through traffic. Never got hit by a car. But that didnt make it a good idea.

I guess if he did get hit, it wouldnt be his fault. Or the drivers fault. It'd be the asphalt.

Pure silicon might not work well, but I was thinking of latex/silicone caulks.
 

cfb

SatelliteGuys Pro
Apr 10, 2009
1,492
1
California
Pure silicon might not work well, but I was thinking of latex/silicone caulks.

I wouldnt ever use a traditional latex or latex/silicone caulk on a roof. In a perfect world, I'd use a tripolymer or synthetic rubber based product. "Through The Roof" or "White Lightning" are pretty good options.

I think the principle use for outdoor silicone is sealing up around windows and door frames.

Correctamundo. And neither doors nor windows are on top of your house.

It's made to expand and contract as it get's warmer and colder outside.
But only to the degree that a door or window and its adjacent siding expand and contract, which is substantially less than what a roof shingle does. Depending on where you live, a roof is subjected to temperature ranges from 0 degrees to 150 degrees over the course of a year.

I've never had any problems with silicone on the shingles cracking and causing gaps.
None that you've noticed or observed long enough.

There's nothing wrong with using silicone on a roof.
And yet you have two people here with contractor connections suggesting otherwise.

It's not like running out into traffic with your pants on your head.
Well you see, I think you missed the point. I also dont think you'd be much fun to party with.
 

harshness

SatelliteGuys Master
May 5, 2007
16,660
2,726
Salem, OR
Some of the locals around here use a soft black neoprene gasket material. Among the advantages over rubber materials is that it is highly UV and asphalt resistant.
 

talos4

SatelliteGuys Pro
May 26, 2005
577
0
SE Wisconsin
I think the principle use for outdoor silicone is sealing up around windows and door frames. It's made to expand and contract as it get's warmer and colder outside. I've never had any problems with silicone on the shingles cracking and causing gaps.

There's nothing wrong with using silicone on a roof.

You've made my point. with your "Principle use" statement.

I don't tell SAT installers how to align a dish, Why do installers keep telling me how to seal a roof?

Is it so hard to carry a tube of roof cement instead of silicone? and the cement is cheaper too!

There is not one specification from any asphalt shingle manufacturer that will spec out using silicone on their product. It's not compatible...Period.

Silicone doesn't seal to the asphalt, It sits on top of the mineral granules. Put a big enough blob of it on and it will divert the water around the blob until it no longer sticks to the granules.

Roof Cement bonds with asphalt saturated felts forming a proper long lasting seal.

Oh and always, ALWAYS cover the bolt heads, there is no seal between the bolt head and the metal foot pad. Water will migrate between them and down the screw.

20 years of commercial roofing and I still don't know how to properly align a dish.
 

wildbill129

SatelliteGuys Pro
Jul 31, 2009
1,273
0
Redding, CA
You've made my point. with your "Principle use" statement.

I don't tell SAT installers how to align a dish, Why do installers keep telling me how to seal a roof?

Is it so hard to carry a tube of roof cement instead of silicone? and the cement is cheaper too!

There is not one specification from any asphalt shingle manufacturer that will spec out using silicone on their product. It's not compatible...Period.

Silicone doesn't seal to the asphalt, It sits on top of the mineral granules. Put a big enough blob of it on and it will divert the water around the blob until it no longer sticks to the granules.

Roof Cement bonds with asphalt saturated felts forming a proper long lasting seal.

Oh and always, ALWAYS cover the bolt heads, there is no seal between the bolt head and the metal foot pad. Water will migrate between them and down the screw.

20 years of commercial roofing and I still don't know how to properly align a dish.

Ditto, I have been doing construction as a career and now a hobby for 20 years. Silicone on asphalt shingles is not a good permanent solution....if silicone was a good roof sealant it would be marketed as such....it's not.
 

talos4

SatelliteGuys Pro
May 26, 2005
577
0
SE Wisconsin
Some of the locals around here use a soft black neoprene gasket material. Among the advantages over rubber materials is that it is highly UV and asphalt resistant.

Neoprene while used in the roofing industry must have a separation material (ideally metal) between it and an asphalt based product.

Asphalt based products will degrade neoprene and any PIB based product such as EPDM, or any other derivation of rubber products. Over time these products will breakdown when in contact with asphalt and cause it to fail. PIB products should only be used together and not mixed with a dissimilar product.

The idea is to have an asphalt compatible material not an "asphalt resistant" one
 

sddtvtech

SatelliteGuys Pro
Sep 17, 2009
1,202
0
in a van down by the river
I use tar patches or pitch patches, to sealed the lags. Yeap, use this or roof cement is optimal.


what you are saying is Bishop tape...


it is MANDATORY that every installer in Directv to use Bishop tape on roof mount. NOT silicone. we only use silcone to fill lag bolt holes if we are REMOVING the dish from the WALL. if it is on the roof and we're moving it, the base will stay but the mast will be removed.



every roof install gets bishop tape in my installs.

only time i will use a Sealant is at the top of the base so the water isnt gonna go under the mast in high wind rain down pour and will direct the water around or over the base of the mast so no water contacts the lag bolts and the bishop take will remain sealing the holes.

also to keep in mind, always mount your dish at the eave instead of the peak of your house... its stupid UNLESS you got Line of sight issues.
 

ranmic

SatelliteGuys Pro
Oct 11, 2009
300
11
Sun, Sun and more Sun!!!!
I use standard Duck Tape to hold the dish in the desired spot. Usually no more that a two rolls are needed.

For sealant I use the Bazooka Joe brand chewing gum. Chew it 5 or 6 times and then plug the hole with it. It works great. Plus when you are done, you have a cool comic strip to read.

but, that's just my method, you may prefer Hubba Bubba or something.
 

Joe Diamond

SatelliteGuys Pro
May 3, 2004
2,596
6
IF you use silicone the trick (a trick) is to allow it to set up under the mast. Then crank down the lag bolts on the set up silicone. The pressure of the bolts compresses the now firm silicone and seals pretty good. Silicone in the thread holes is good too and a bead across the uproof edge can't hurt.

The Commdeck application looks pretty good!

Joe
 
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