# Good flashing detail for 1 1/4" pipe?



## bheilig (Jun 14, 2012)

Hi,

I penetrate a lot of Modbit roofs with standoffs for solar arrays. The standoffs are 1 1/4" steel pipe, and they meet the roof at a steel flange that is about 4" square and 3/8" tall. For structural stability, I cut away a square of existing felts all the way down to the deck, sometimes 1-2" deep on older roofs. This way I can land my flange right on the wooden deck.

I've been using a trowel to tightly fill the resulting square holes with Karnak #19 flashing cement, then topping the pocket with a rubber pipe flashing, sealed at the edges with Chemlink Duralink - this is a general industry practice that I've picked up here and there from other tradespeople. So far, 1+ year in the field and no leaks. But I'm wondering if anyone has any feedback about this; am I making a serious mistake or skirting very close to it? If not, is there a way to improve this detail's lifespan? I'm considering adding an aluminum coating to the pocket before the pipe flashing goes down.

Feedback much appreciated!


Bret


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## Grumpy (Oct 29, 2008)

1 year is temporary and long enough to get paid. If it lasts 5 years that's adequate, and 10 years you'll have my respect. 

Having said that, the rubber pipe flashing is a great touch. I would first wrap with ice and water shield before installing the boot however.


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## bheilig (Jun 14, 2012)

Hey thanks Grumpy, can you link me to this water-shield product you're talking about?


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## 1985gt (Dec 21, 2010)

Metal pitch pan 1 layer of base sheet around pitch pan 1 layer mod bit over that. Fill pitch pan with karnak.

View attachment MB-P-04_2006_01_01.pdf


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## Grumpy (Oct 29, 2008)

1985gt said:


> Metal pitch pan 1 layer of base sheet around pitch pan 1 layer mod bit over that. Fill pitch pan with karnak.
> 
> View attachment 1128


This is a shingle roof we are discussing, no?




Ahhhh crap I just reread and saw it was a mod bit roof. I take back what I said in my previous post. Sorry. 

A metal pitch pan is the best way to go.


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## 1985gt (Dec 21, 2010)

Grumpy said:


> This is a shingle roof we are discussing, no?
> 
> 
> 
> ...



On the same note has anyone else tried the chem curb kits? 

http://www.bestmaterials.com/detail.aspx?ID=16749

We tried these not to long ago on some guy wires for a tall paint stack on a BUR roof. We let the customer (long time customer) that this would be an experiment and if something went wrong we would come replace it with a normal metal pitch pan. The installers loved them, much nicer then working with mastic. I hope it holds up we will see though. 

Just wondered if anyone else had any long term luck with them.


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## Grumpy (Oct 29, 2008)

I have had a chance to inspect a few that have been done by others and they really seemed like a decent product. I've used the chem sealant for other kinds of pitch pans in the past though. 

GT, even when installing a pitch pan on a modified bitumen roof, which you probably know I've eliminated the installation of modified bitumen for the most part from our service offerings, we still would use a product similiar to the chem sealant in the pitch pans. I've seen way too many problems using mastic as a pitch pan sealant, and mastic as a pitch pan sealant requires way too much maintenance when compared to other pitch pan products.


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## 1985gt (Dec 21, 2010)

A good amount of the time we will use SL-1 very good product but you can have absolutely no holes in the bottom. You have to detail around the pipe or what ever first then install the SL-1, otherwise it all ends up inside of the building.


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## Jared (Jul 9, 2012)

Sl1 truly does run like water. I love it and and np1, both made by sonalastic.


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## Grumpy (Oct 29, 2008)

1985gt said:


> A good amount of the time we will use SL-1 very good product but you can have absolutely no holes in the bottom. You have to detail around the pipe or what ever first then install the SL-1, otherwise it all ends up inside of the building.



No matter what sealant we are using we will typically fill all holes, often with caulk, or with mortar or spray foam if larger than caulk will fill, before adding the pitch pan sealant. That's just our S.O.P.


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## 1985gt (Dec 21, 2010)

Yeah we do to, but you have to be extra careful with SL-1, it will flow through the smallest of holes.


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## Grumpy (Oct 29, 2008)

Never used it... more runny than the versico pitch pocket sealant?


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## 1985gt (Dec 21, 2010)

Yes not as thick as the pour-able sealer. Has about the consistency as TPO cut edge sealant.


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