# Inset dormer metal pan flashing



## forsmant (Dec 12, 2008)

Does anyone know where I can find a detailed best practice on this subject? I have been searching for 3 hours to no avail. Today I was responsible for putting down the ice and water shield but was interested in how to do the actual metal pan.


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## red_cedar (Mar 30, 2005)

Soft cover book called 'slate roofs'. published in the 1920's
Should have the details you are inquiring about.


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## Grumpy (Oct 8, 2003)

Metal work is a craft, something that takes practice and one mistake can ruin hours of work. It's measure 4 times and bend/cut once. I live by the motto, if you can draw it, we can bend it. And if we can;t I work with a few fabrication shops who can. 

Do you have a pic of the project, I can likely draw something on cad for you within a few minutes.


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## UpNorth (May 17, 2007)

*Is this what we are talking about?*

I have a similar situation, I think. Wondering how best to detail the deck floor. Materials, walk surface, drop from inside subfloor, pitch to drain or scuppers, etc., etc.

A design is to include a small deck outside a half-story up bedroom. One of those dormer porches that needs to be designed to drain like a deck built on a flat roof.

The attached pic shows the rough workup. As can be seen, the deck in the roof cutout is presently the same elevation as the subfloor of the second floor.

I've not done one of these, and wish to learn best practice for detailing and building. If you have done some, and can share some CAD details, I would appreciate it.

Specifically, I am wondering:

1. Are these done as a membrane roof, pitched to scuppers or drains, and clad atop with duckboard walk surfaces?

2. What is the recommended drop from inside-room subfloor, to outside deck roof surface (the waterproofing layer under the duckboards?)

3. How are the three outside walls that form the parapets around this "roof" best flashed to the roof pan?


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## Grumpy (Oct 8, 2003)

Hi I don't know what a duckboard is, sorry. 

From the pic, i can't quite tell, will this have a wall on all 4 sides, or will it be open on one side? Personally if it were me specifying the project, I would install a single ply membrane fully adhered over a high density fiberboard and install neoprene walk way pads over the top of the membrane. 

If there is wall on all 4 sides, as it appears there is, then you will need an internal roof drain and I have seen these things leak many many times. 

I'd bring the single ply membrane at least 2' up the walls, fastened with a termination bar. Then I've bring a tyvek house wrap to cover the rest of the walls, and overhang onto my single ply memebrane a couple inches and tape the tyvek to the membrane using a tyvek tape. I wouldn't install the siding all the way to the bottom like the pic shows or risk ice back up (assuming you are in a snow area) through the nail holes for the siding. 

Another thing, I would want there to be a 4" step at the bottom of the door to the top of the roofing. having had to deal with many projects in the past and having the threshold of the door flush with the roof, let me tell you that's always good for a ton of swear words from the roofer's mouth. A 4" step is best because if for some reason there were any back up the water could pool in theory 4" before it backed into the house. Also it makes it possible to properly terminate the roofing membrane under the door threshold.


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## tinner666 (Nov 3, 2004)

Just follow SOP from Revere about flat-lock copper roofing. The have details onsite and in 'Copper and Common Sense" details book.


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## seeyou (Dec 12, 2008)

1. Are these done as a membrane roof, pitched to scuppers or drains, and clad atop with duckboard walk surfaces?

My preference would be to scupper it. Less chance of catastrophe.

2. What is the recommended drop from inside-room subfloor, to outside deck roof surface (the waterproofing layer under the duckboards?)

Drop the outside floor level at least 4" as mentioned above with a 1/4"/ft min slope. If the walking surface needs to be level with the subfloor, build a floating deck on sleepers and install it over the waterproofing material.

3. How are the three outside walls that form the parapets around this "roof" best flashed to the roof pan?

The flashing would be a continuation of the roof pan material behind the housewrap as mentioned.


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## seeyou (Dec 12, 2008)

forsmant said:


> Does anyone know where I can find a detailed best practice on this subject? I have been searching for 3 hours to no avail. Today I was responsible for putting down the ice and water shield but was interested in how to do the actual metal pan.


See above. Ignore the scupper advise.


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## Tom Struble (Mar 2, 2007)

tinner666 said:


> Just follow SOP from Revere about flat-lock copper roofing. The have details onsite and in 'Copper and Common Sense" details book.


 
i got that book:thumbsup:


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## ApgarNJ (Apr 16, 2006)

I don't think he's talking about like something in that picture, he's talking about a dormer that is recessed into the roof. we just did a farm house a few months ago, where there is a slate roof, 3 A dormers each with a window in it. we were replacing the windows. 
the bottom was flat, down and clipped on the front up the two "triangle" shaped sides and back under the slate going up the sides of the dormers. the back went up and over the framing for the window, soldered and then window was reinstalled and vycored around, then azek. came out really nice.

anyone who is good at copper work can do this. i wouldn't suggest it out of aluminum because it would rely too much on silicone or sealants.
with copper you can solder back two corners.


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## jmiller (May 14, 2010)

I would lose the door and make it a window, then the flat roof decking would pitch off onto the shingles, since it wouldn't need that 'wall railing' opposite the window.

OTOH you could keep the door, make the flat roof pitch onto the shingles (lose the 'wall rail), and build a proper rail, which would give you more square feet of deck as well. I kind of wonder though, why would someone really want to go out there. Is there enough room for two people? chairs?

Whatever the case, you're much better off letting the water run off along the whole width of the roof than creating a swimming pool with scuppers/drains.


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## UpNorth (May 17, 2007)

OK. Here is where I have landed with the design, after seeking and getting lots of valuable input. Thanks to those here for contributions.

A note about overall config. The design is fixed, and a well with a three-sided parapet is what it will be. I cannot control that, but I must specify components and details that will work. This is a three-season vacation house, and will rarely be occupied in winter. A fall shutdown will drain all pipes, and the place will be unheated during winter snowfall time.

One floor drain will be centered along the outboard end of the small deck, and its outflow will exit toward the outboard edge of the flat soffit. An overflow scupper will be made integral to the drain, and will be set atop it, draining straight out through the roof.

The door will be purchased in a custom height, shortened by 6 inches, and set atop a 6" curb. One will need to pretend one is oboard a ship, where one steps over tall thresholds to pass through doors.

The deck will be pitched to drain at a slope of 1/4" in 12 inches, and the waterproofing will be a system such as Dexotex Weatherwear, for which a product description is attached. This product was recommended by two experienced architects, one of them also a general contractor. 

The Dexotex package will be installed by one of their qualfied contractors, and all flashing and details will be per their recommendations. Dexotex has details at their website, in CAD format (.dwg), and all available for download.


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## Grumpy (Oct 8, 2003)

wow 3/16" thick that's pretty massive for what is essentially a reinforced elastomeric. It said latex twice meaning it's water based, meaning water will break it down over time. I know nothing of the product other than what you posted above.


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## UpNorth (May 17, 2007)

Everything breaks down over time. Did you see the article about trowel-on roof deck coatings, the kind that function as "promenade surfaces," meaning you can walk on them, in the recent issue of the Journal of Light Construction?

Go to the Dexotex website and have a look. They make a whole range of materials used in commercial and industrial settings. If you win the award to roof the new downtown lofts being done in near-North yuppieland, those rooftop tennis courts will be clad in a material like this. Our son's condo up on Marine Drive has its rooftop swimming pool court waterproofed with something like this.


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## ApgarNJ (Apr 16, 2006)

EPDM that thing. i'd be more worried about snow filling up that pit and the door leaking as it thaws, freezes. horrible design and the people will rarely go out there. they will regret that little porch/door inset for a while once they see what a pita it is down the road.
I think the front wall should be eliminated as posted above and put a railing there. then the water can drain down the roof and you can slope it. plus gaining a little more deck space. that space is absolutely useless, two people can maybe fit out there standing and no way any chairs or a small table can go there. 
either fiberglass it and make a pit that way or epdm and throw an extra layer of epdm over the first layer loose, then have a removable wooden deck platform to stand on so you aren't putting holes in the EPDM. that will last the longest, any kind of coating or rolled roofing will only last a short while and then leak/rot out the areas below before they even know what's going on because they won't be there every single day.

I think this thread kinda got offtrack from the original post as I don't think the OPer has the same situation with a pit. his may be a dormer with slopped recessed bottom without that wall like the above picture shows. but without a pic of his, hard to tell.


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## Grumpy (Oct 8, 2003)

UpNorth I am very familiar with elastomeric systems. I am simply not familair with that product. Yes every item will break down over time, but putting a product that isn't really puddle resistant in an area where there will be puddles isn't a smart idea. See if the deckotec or whatever has a urethane based product. That'll be much more puddle resistant.


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## neolitic (Apr 20, 2006)

If that pit is in snow country, they are
building a leak, heated or not.
There will be heat gain through
windows, and if the place is insulated
it will be warmer than the outside.
If that door faces south, it's going to
melt the snow trapped in that pit.
Residential doors don't have 
water-proof seals.
I would have a huge liability disclaimer
for that mess, at the very least.
Did I say that is a piss poor design?


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## ApgarNJ (Apr 16, 2006)

neolitic said:


> If that pit is in snow country, they are
> building a leak, heated or not.
> There will be heat gain through
> windows, and if the place is insulated
> ...


that's why i said it was stupid. some people design things not realizing how stupid they really are in a house. super tiny balconies where no one can really spend much time are a waste. and so many of them leak down the road. there are better ways to do that, but making that wall in the front instead of an open railing is asking for disaster.


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## Grumpy (Oct 8, 2003)

neolitic said:


> If that pit is in snow country, they are
> building a leak, heated or not.
> There will be heat gain through
> windows, and if the place is insulated
> ...





ApgarNJ said:


> that's why i said it was stupid. some people design things not realizing how stupid they really are in a house. super tiny balconies where no one can really spend much time are a waste. and so many of them leak down the road. there are better ways to do that, but making that wall in the front instead of an open railing is asking for disaster.


You're both exactly correct on both counts. I don't think I or anyone could have said it any better.


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## UpNorth (May 17, 2007)

Wow! What a bunch of grump nay-sayers! Do you folks get out much, like, maybe into the world of commercial contracting, where deck coating systems by outfits like Sonneborne, Sika, Tremco, Dexotex, and others, get used?

If the client wants a well dormer with observation deck, the client is going to get it. The problem is that the high net worth types, the only ones who are able to afford to build new stuff in my locale, where all that gets built, mostly, are second homes, come here for a visit, and stay here: http://lakeplacidlodge.com/#/information/lake-placid-lodging

Or they stay at the place over on the other lake. This one. http://www.mirrorlakeinn.com/ Well dormers everywhere.

They enjoy their cozy little observation deck in the well dormer of the room, then go and buy a nice view lot somewhere, and want the well-dormer-feature built into their new little "camp."

If we need to heat the drains, we will.


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## neolitic (Apr 20, 2006)

Don't ask for opinions
if you don't want opinions.
I've only seen water proof doors
on ships.


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## UpNorth (May 17, 2007)

It wasn't opinions it was after. It was advice from ones who had done well dormers.

Here is the problem. The high-net-worth clients come here and stay at one of the two bigticket hotels, either the Lake Placid Lodge or the Mirror Lake Inn, both of which have rooms with these well dormers, and cozy little observation decks looking out at the scenery.

Then they want the same feature built into their new little lakeside camp.
See here what I am talking about. http://lakeplacidlodge.com/#/information/lake-placid-lodging. The main building has over a half dozen of them, visible in the photo album.

There are more well dormers with observation decks, and front walls just like all the rest, that can be seen on some of the private lakefront homes, also, while one is touring around in the old '29 Hacker Craft Dolphin Junior runabout.


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## ApgarNJ (Apr 16, 2006)

just make sure the door is water proof. good luck. no one around here has them, and for a reason.

i hope you do your homework good on this one as it would be hard to fix later on when leaks occur.

make one big step into that doorway to avoid ice damage.

one thing about hotels is that they are maintained better and always heated in the winter. you are talking about a house that the people won't be there that often and no heat all winter. just no one around to really see the problems that can come up with a design like that.


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## Grumpy (Oct 8, 2003)

UpNorth said:


> It wasn't opinions it was after. It was advice from ones who had done well dormers.


That's what I gave you. 



Good luck.


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## forsmant (Dec 12, 2008)

I was talking about walls on three sides. A fourth wall is asking for trouble. The guy who we hired to do the pans is using aluminum. The ones We tore out were galvanized. The guy we have doing the new pans came highly recommended but is not living up to that reputation. There is a standing seam in the middle and the "bends" at the side walls are rounded. He used two pieces. I do not like the look and was interested in knowing how to do it the best way. The book I found on the internet is called the Slaters Bible.


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## ApgarNJ (Apr 16, 2006)

copper!!! never use aluminum for something like that. you can't rely on silicone or sealers long term. copper can get bend easily and soldered, end of story. you are talking about three sides, that is the better way to go. someone else chimed in with that pit in the roof that they were doing and that is all trouble, i don't care how much money the client has. it's a stupid idea.

I explained in one of my first posts how to do this with copper. I just got done doing three of these on a window job for a 1700s farm house with slate roof and has three recessed A dormers. copper was the best thing to use here. i can't imagine getting long term results with aluminum because the back two corners will have a pinhole from the bends and needs to be soldered, you can't do that with aluminum. sure sealers would work for a while but eventually it's going to leak. solder will last a lot longer, i'll be dead before those pans we did leak.


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