# Sealing torch on to existing 4-ply



## Graves (Jun 24, 2009)

I am looking for an easier and less labour intensive way to do a temporary seal from a new Modified bitumen torch down membrane roof to an existing 4-ply roof system. All I need is a temporary seal that will last until the next days rip but obviously it has to be water tight. 

Currently we are scarifying the seal and adding a quick primer coat and torching the seal. 

Let me know any tricks of the trade you have on your job sites.

Thanks,


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## Grumpy (Oct 29, 2008)

I'm confused. Is the 4 ply bur imbedded with gravel? I've never had a problem sealing modified to smooth bur before with nothing more than a quick flame prime.


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## rwolfe (May 14, 2009)

Considering you indicated "scarifying the seal" we'll assume that meant your spudding the tie-in. 

If I'm not mistaken, thats the way to do it. Not sure I would use a torch grade material on it unless that's all you have on site. I always liked to use a patch kettle and mop down a heavy base sheet then glaze.

When the rain is coming and I'm in a hurry and cant get the bur spudded. Used to broom loose gravel back, flood the gravel, let asphalt cool. Then mop a heavy base in fresh asphalt. 

I'd be interested to know if there is a "trick of the trade" on this one.


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## Graves (Jun 24, 2009)

I have never heard the term spudding...lol great word!

Grump: the gravel surfacing is of course removed, primed, and scarified or spudded approximatly 12" to 18" to the base 4-ply membrane . I am just looking for a time saving alternative.

Wolfe: I certainly agree that hot bitumen is the best way to seal. Mop and stick the seal is the best and quickest but this job is a complete torch down system. I don't want to put a pot on-site, and use labour, and propane to heat a pot just for a seal. plus we are talking approximatly 30 272' seals. That is a pile of expensive bitumen. 

After posting this a article I priced using a pourable sealer or adhesive but the cost are close to double that of hot bitumen. So much for trying to reinvent the wheel. If anyone else has any ideas feel free to post.

thanks,


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## Grumpy (Oct 29, 2008)

I do it the way you do it Sean, on modified. It's the only way I know how, except for hot, but we don't do hot.

On single ply we use a pourable sealer. Genflex has a spec for this on their website. We used a night seal of pourable sealer to get us through a tremendously terrible 3 month winter on a roof we started in November but didn't finish until March due to weather. The pourable sealer held without a drop of water into the building.


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## rwolfe (May 14, 2009)

Are you kidding? Pourable sealer $40 a can!

30 tie ins 18" wide. If you used 50 lbs per square which is maybe 20% more than what you would actually need that would cost you about $1,600 give or take. Another $1,100 in base sheet. You'll need two sticks a day or 10 per week. This is hardly a pile. If $1,600 is too much for you, you can tie in 12" instead of 18".

Currently your probably wasting a half of a roll of torch grade interply at around 50 per square? My math is showing a 18" tie in costing about $6,100 in roll goods only, not including priming. and chances are, you may be wasting more than 1/2 roll of torch.

Someone correct me if i'm wrong, but I'm thinking this question just got answered.


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## Ed the Roofer (Sep 15, 2008)

How cheap or expensive would it be to just use a 1/2 roll or even a full width of 43# base sheet and Lexuco Glue or the adhesive they sell for SIS, (Seventeen Inch Selvage), that you used to be able to install with a squeegee?

Ed


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## rwolfe (May 14, 2009)

I dont know what luxuco glue or SIS is. But I would have to think it's no cheaper than asphalt. Whatever it is.

But $1600 is nothing on what appears to be a considerable project.

30 tie ins 270 feet long. 

No matter what, you're spudding or scarifying the existing roof back. Therefore the labor dollars will get spent no matter what.


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## rwolfe (May 14, 2009)

I was wondering if there was a trick to the trade on this one.

Guess not.


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## AaronB. (Nov 23, 2008)

Meka sure the BUR at the tie in is in good shape, meaning able to accept a watertight tie in, sweep the gravel back, prime with gasoline, allow to dry, mop right to it.

DO NOT TRY THIS ON YOUR ROOF! It is unsafe due to the presence of gasoline.


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## Grumpy (Oct 29, 2008)

I do not allow my workers to use gasoline in any form to do anything except its' intended purpose which is to fuel vehicles and mechanical equipment.


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## AaronB. (Nov 23, 2008)

Exactly why I said not to do it. He was asking for tricks of the trade. He didnt ask for SAFE tricks of the trade.

That was how all those old union guys I apprenticed with used to do it. I spud and burn.


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## Grumpy (Oct 29, 2008)

Yeah I knew an old union guy that would use gas for everything. He'd make primer with dope and gas. He'd wash everything with gas, his hands and tools. How he wasn't burnt alive is a suprise to me. Maybe because he didn't smoke. I think if he did, he'd combust from having all that gas absorb through his skin and into his blood. 

I'm not saying it doesn't work because it definetly does, but man it's dangerous!


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## RooferJim (Oct 20, 2008)

scratch and burn, if there is a lot of rain coming trowel down some karnak and membrane over it as well. "another old union guy"


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## AaronB. (Nov 23, 2008)

Yep, don't forget to dope check the tie in!!!!


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