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Flash me! (Show your work.)

Wood Guy

Last Wednesday my friend Aron Jones at Big Dog Builders on Grand Manan Island in New Brunswick (https://www.instagram.com/bigd...) declared it "International Flashing Day." He sent me some bling (https://www.instagram.com/p/CT...) and a lot of others helped promote the idea. Who knows, maybe it will become an annual thing?!

In belated honor of #internationalflashingday and Chad's suggestion, let's see your best (or worst) flashing details!

 
Sep 3, 21 8:52 am

Since this was my fault I'll start.  A nice boring parapet flashing detail that we've used a lot. 


Sep 3, 21 10:52 am  · 
3  · 
Wood Guy

Chad, I always appreciate how clear your drawings and sketches are. And I thought it was a great idea for a thread.

I recently consulted on a residential project with parapets that were not sealed at the top and communicated with the interior, which ran at negative pressure and caused water infiltration, requiring full siding and sheathing replacement after just three years. (It was designed and detailed by a FAIA architect, FWIW.) 

Sep 3, 21 11:41 am  · 
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SneakyPete

Why this instead of a cap?

Sep 3, 21 11:44 am  · 
1  · 

More water tight because of less fastener penetration's. Also quicker and less costly to install.

It's also important to note that this is for a climate with no snow.  

Sep 3, 21 11:49 am  · 
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SneakyPete

The reliance on that single bead of sealant is what I can't wrap my head around, won't UV destroy that in a matter of years? Please know that I am trying to learn, not just shitting on your work. I trust you've thought of this stuff and I'd appreciate it if you shared what you know.

Sep 3, 21 11:55 am  · 
1  · 

That bead of sealant is really there to finish the cut edge of the membrane flashing. It's not necessarily critical to the detail. If it fails, you still have the continuous roof flashing membrane underneath that terminates on the front side of the parapet. It's needed, but it's not the only thing keeping water out.

Here are a few other options. These are all shown on a flat roof edge, but would work the same on a parapet edge like Chad's detail shows. Sorry they are all from Carlisle at the moment (I was already on their website to grab the detail I shared further below).

https://www.carlislesyntec.com... (This would be my preference to upgrade Chad's detail)

https://www.carlislesyntec.com...

https://www.carlislesyntec.com...

https://www.carlislesyntec.com...

Sep 3, 21 12:41 pm  · 
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As EA said the bead of sealant isn't critical to the the waterproofing of the detail. Wrapping the membrane flashing is however.

Also the sealant won't be destroyed by UV damage in a number of years.  The sealant is the same as used on the roofing membrane.  

Sep 3, 21 12:43 pm  · 
1  · 
SneakyPete

I learned today! Someday I might detail a membrane roof instead of these metal ones and interiors. :D

Sep 3, 21 12:57 pm  · 
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b3tadine[sutures]

I'm always curious about chamfered edges on plywood no one sees, and generally feel the installers just disregard. What's been your experience?

Sep 3, 21 1:00 pm  · 
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The installers want to disregard the chamfered edges. We make it clear that not doing the edge as we show voids the roofing warranty.

Sep 3, 21 1:23 pm  · 
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mightyaa

I'll play. This is an in process concrete balcony flash. The general assembly is a fluid applied waterproofing, sloped to spill edge. Drainboard over that, topped with concrete wear surface. A common issue is at the wall to deck interface, moisture gets channeled behind the wall finishes. That location is also a weak WRB location as the wall WRB's are cut around the projection. So I use a half saddle flash and install a diverter to force moisture away from the weak point.

What you see; the silver metal along the wall is just a metal protection layer for the waterproofing rolling up the wall. The other silver metal is essentially the pour stop and fascia of the concrete. The duct tape is at the drainboard. But you'll see the brown metal; that is the diverter and set in with the fluid waterproofing fully wrapping the corner. Wall WRB will be properly lapped and the microlam will be covered with more flashing before finishes are reinstalled. 



Sep 3, 21 11:04 am  · 
1  · 
mightyaa

And a partial of the repair detail; changed during construction later when we found fluid applied instead of membrane and tweaked it.


Sep 3, 21 1:20 pm  · 
1  · 

Is that Garden State Brickface?

Sep 3, 21 9:49 pm  · 
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mightyaa

Here's a before location on a 2 year old building without this extra level of effort in flashing showing the moisture infiltration that will only get worse. btw; the soffits were heavily moisture damaged too.


Sep 3, 21 11:08 am  · 
1  · 
mightyaa

$10 million dollar mistake. Tons of installation defects, but the designer didn't want to see waterproofing above dirt in the planter boxes over podium. Water went behind, because duh, your sprinkler system is watering the hell out of this (as compared to just rainfall like your roof would see). At the bottom of wall, the waterproofing delaminates, makes big water pockets, and burst... now a bigger hole in your system. The repair is stripping the entire podium and redoing it. (lots of other issues too). Oh, another here; no flashing under the cap either. Opposite side, they also didn't want to see waterproofing over the walk, so surface flow can also get behind the waterproofing on the opposite side of the wall.


Sep 3, 21 11:26 am  · 
1  · 

This is such a common detail and it drives me crazy that we are still making this mistake. Good share.

Sep 3, 21 11:53 am  · 
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SneakyPete

Might also help if the budget allowed for more plants at the beginning to be thinned over time so the black waterproofing would be hidden underneath the lovely plants.

Sep 3, 21 12:10 pm  · 
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You don't want your waterproofing exposed above grade. Instead use a PMMA liquid-applied flashing product to transition from the below-grade waterproofing to be exposed above grade. Options are available in a range of colors.

Sep 3, 21 12:22 pm  · 
1  · 
SneakyPete

You might intuit (correctly) that I have not built one of these. Still spring for more plants if you don't like the look of the PMMA liquid-applied flashing product. :)

Sep 3, 21 12:34 pm  · 
1  · 
mightyaa

EA... correct; It should never be directly exposed to UV. So you need to cover it. So here's the correction detail we put back with a stainless cover plate.


Sep 3, 21 12:54 pm  · 
2  · 
mightyaa

And what it looks like going back in. Also note weeps near the walk surface; blocks below the weeps are facers covering the waterproofing behind. That is so I could ensure the waterproofing was always higher than any flow surface. (precast hasn't been installed yet obviously)

edit; should also note the actual podium waterproofing is about 2' below the concrete walks. Also had to reslope it to drains because the original design used a 1/8-inch slope which, after deflection, did not flow any water (several large deep puddles were found at the waterproofing level in multiple locations).


Sep 3, 21 1:01 pm  · 
2  · 
Wood Guy

I drew this detail a few days ago for a new, high-performance house on the Maine coast. We're going for Passive House certification but it will be close whether we make it due to way too much west-facing glass, but that's where the ocean is, so... Getting the water control layers right for an "innie" window and trying to eliminate thermal bridges, with budgets that are always tight is a challenge. I'm trying to develop a standard detail for this situation but every project has different requirements. This is an internal document; I have an architect modeling in Revit, but he won't use the pretty colors. 

Sep 3, 21 11:33 am  · 
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tduds

Great thread. Not sure if I have anything I can (read: am allowed to) contribute, but if I can I'll sneak something in.

Sep 3, 21 11:39 am  · 
2  · 
Wood Guy

Shameless plug for The BS* + Beer Show (*building science), one of my side projects: our topic on 9/16 is flashing details! We'll have some well-known US builders on to talk about how and why to flash properly. https://www.thebsandbeershow.c...

Next Thursday, 9/9 we have building science legend John Straube on to talk about rainscreens. 

Sep 3, 21 11:45 am  · 
4  · 
Non Sequitur

Hot damn!

Sep 3, 21 12:01 pm  · 
1  · 
Wood Guy

I thought you'd be happy!

Sep 3, 21 12:17 pm  · 
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I don't have a project specific image or detail I can share for this. The scupper detail below is taken from Carlisle, but generic enough to work for most manufacturers.

Most single-ply roofing manufacturers have coated (or clad) sheet metal flashing where they have their PVC/TPO membranes on one side of sheet metal. Makes detailing roof edges, parapet scuppers, etc. a lot easier when you can heat-weld all the seams. If done correctly per manufacturer details you can also get the whole thing covered under the roofing warranty. 

Sep 3, 21 12:08 pm  · 
2  · 
SneakyPete

Manufacturers get a lot of flak but they have a massive financial interest in developing details that will keep them out of settlements and courtrooms.

Sep 3, 21 12:11 pm  · 
2  · 

I'd estimate about a third of my comments on any set of drawings are pointing out the manufacturers' details to people who thought they could just make something up.

Sep 3, 21 12:16 pm  · 
3  · 

Manufacturer details are a valuable resource. Check out Firestone's detail library as well.

Sep 3, 21 12:42 pm  · 
4  · 
joseffischer

same, still haven't convinced anyone that we can just slap the manufacturer numbers for details on a set rather than draw them.

Sep 7, 21 10:14 am  · 
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I think that could be a bad idea Josef. The manufactures details rarely go beyond their own work and typically have to be revised to work with the assemblies they are being incorporated into.

Some details can by used without modification.  It's not hard to copy and paste those into a drawing set.

Sep 8, 21 12:35 pm  · 
1  · 
natematt

Been doing a lot more axons lately. 


Sep 3, 21 1:11 pm  · 
2  · 

I've been doing more axions recently as well


Sep 3, 21 1:21 pm  · 
3  · 
mightyaa

It's great that you guys are doing axiometric details. Often flashing turns corners and is too complex of a shape to capture in a 2-dimensional section. If you look at my one above, we've started step by step to show the layering as well so it's more like a lego instruction book.

Sep 3, 21 1:28 pm  · 
2  · 
natematt

We've been doing them for flashing in particular due to client waterproofing consultant requests. I like partial systems, but for a lot of other applications they are not that clear. I like your first one as I think it's helpful to understand the systems coming together, the second one seems like i'd get more out of just a flat section detail... which I am sure you also had.

Sep 3, 21 1:29 pm  · 
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Non Sequitur

Very erotic 3D details.

Sep 6, 21 9:25 am  · 
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joseffischer

We specifically don't provide 3D details like the above as the higher brass feels like it opens us up to all kinds of E&O conversations... "well you provided a 3D detail here, but not there, so isn't that an omission?" I'm impressed with the details above, don't think many in my office could reproduce efficiently, and I wonder how you guys handle when to provide vs not. I will gladly provide response in 3D to a RFI... but usually a sketch will do in those instances, drawn over a photo in field.

Sep 7, 21 12:41 pm  · 
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The details I drew were done in Revit using a combination of a 3D view pasted into a drafting view. I then drew filled regions and detail lines atop it. I figure each took me about 30 - 45 minutes.  This included the time it took to figure out the detailing. 

I decided to do the axion details because I could clearly illustrate the assembly in one drawing vs. doing six.  It's not going to be useful for every occasion, however they can be useful.  


Sep 8, 21 12:40 pm  · 
1  · 
SneakyPete

I cannot imagine that inside corner being done right with only 2d drawings. I am also interested in seeing the end result. It seems a very ... odd corner.

Sep 8, 21 12:51 pm  · 
1  · 
joseffischer

do you guys not do mockups anymore? we do mockups everywhere at these specific types of locations and just handle it via mockup

Sep 8, 21 1:08 pm  · 
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We do mockups. Doing this axion not only helps us figure out the assembly and it's appearance but also decreases the time it takes to build and approve the mock up.

As I said before - the axion was warranted in this situation since it saved so much drawing time and detailing. 

Sep 8, 21 1:20 pm  · 
2  · 

Sneaky - it is an odd corner. Here is a construction progress pic


Sep 8, 21 1:22 pm  · 
1  · 
joseffischer

hmm, that entire condition would have not survived our QC process to begin with... brick would have been dropped down to be consistent all around. Not critiquing, and in fact glad to see people working through their details to maintain proportions decided during design

Sep 8, 21 4:28 pm  · 
3  · 

That's kind of what we do as architects. At least so I've heard . . .

Sep 8, 21 6:12 pm  · 
1  · 
natematt

This drawing set wasn't finished, and will never get built, but there was lots of coordination with waterproofing consultants and precast design build for the whole project. Lots of new systems I had never worked with. 


Sep 3, 21 1:22 pm  · 
1  · 
randomised

this thread reminds me of how much I enjoy making technical drawings and solving complex puzzles in 3 dimensions...thanks for that!

Sep 6, 21 2:05 am  · 
2  · 
Non Sequitur

Vacation ends tomorrow, hopefully I’ll find some time to add something here once I clear the backlogs of fires and whatnot when I get back in the office. I’m a big fan of 3D details and I’ll often whip up a quick one in sketchup. Easier that way than make a revit version and even faster than using 8 2D drawings and half a thesis’ worth of notes.



Sep 6, 21 9:28 am  · 
2  · 
Almosthip

TPO roof to wall flashing detail

Sep 7, 21 11:33 am  · 
1  · 
joseffischer

We've had success taking the TPO flashing (different from the field material) up the walls up to 3' and wrapping the parapet while maintaining warranty. We like this so that there's no finger pointing between trades/manufacturers if there is a leak (though we haven't experienced a call back on the projects I've been involved with). Past 3' and Firestone wants us to use someone else and provide the term bar. YMMV with your own basis of design

Sep 7, 21 12:37 pm  · 
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joseffischer

We also have school systems that modify all these standard details to show 12" or 14" (two different school systems) so in theory they have room for roof-overs... not sure why they need the 4-6" as that's a bit overkill for a roof-over, but it's in their standards

Sep 7, 21 12:38 pm  · 
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tduds

Should that top fastener be under the flashing?

Sep 9, 21 11:05 am  · 
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Can't be - it's what's attaching the flashing. I suspect you'd seal it with the same roofing sealant used on termination bars and such. Should be watertight as long as the roof is.

Sep 9, 21 1:31 pm  · 
2  · 

I do like that you have the two-piece counterflashing so you can access the termination bar to tear off the roof without needing to remove the cladding. I'm with tduds though and I'm not a fan of the fastener being exposed. Better to have it behind the cladding, but the detail doesn't show what the cladding is. The flashing receiver (called out as drip edge) would ideally be incorporated into/behind the cladding system with a concealed fastener. Lots of ways this could be done. It kind of all depends on what the cladding is above.

The other issue I see is that there isn't continuity of the building's air barrier (assuming the roof membrane and tyvek weather barrier are acting as the air barrier).

Sep 9, 21 1:56 pm  · 
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I wondering if the exterior finish isn't shown in the above detail?

Sep 9, 21 3:10 pm  · 
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I thought the same. It could be fine to not show the cladding if needed for clarity. I'm not sure that would be the case for a detail like this. Maybe the detail could apply to multiple cladding options. If that's the case, I'd still like to see a dashed outline and a note saying "see elevations for cladding type" or something along those lines. You could even call out as many other cladding details as needed for that bottom of cladding termination detail.

At any rate, it seems like we're missing information from the detail.

Sep 9, 21 3:46 pm  · 
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True. I just assumed (whoops) that this was an in progress detail.

Sep 9, 21 4:42 pm  · 
1  · 
Almosthip

EA - Properly installed metal flashing is classified as an air barrier.


Sep 9, 21 4:12 pm  · 
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So is properly installed peanut butter ... but the question is what is "properly installed" and have you detailed it here? Seems like you're missing some detail if that's the goal.

Sep 9, 21 6:29 pm  · 
1  · 
Almosthip

Sure its not a complete wall section this lap detail part of a complete set of construction documents. The cladding is variable as it changes depending on where you cut the section. And the section details show the cladding with the drip flashing. This is just a membrane lap detail at a large scale.

Sep 10, 21 10:41 am  · 
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Why not have a dashed line with a note stating to reference wally types for exterior wall finish?

Sep 10, 21 11:19 am  · 
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Almosthip

I have wall sections that reference this detail and the detail references back to the relevant wall sections. Do I really need more than that?

Sep 10, 21 12:11 pm  · 
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Personally I'd say yes. It's only a couple of dashed lines and a few words of text.

Sep 10, 21 12:12 pm  · 
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Yeah, I think you need the detail to show how the flashing integrates with the wall cladding. Otherwise you'll get a lot of finger pointing if/when it starts leaking ... possibly even before that when it's not done during construction.

Sep 10, 21 12:33 pm  · 
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Almosthip

As I said above I have a section detail that show how the flashing is integrated with the wall cladding, (3 separate details showing 3 different wall claddings to drip flashing) This is a roof membrane lap detail. Anyways its part of a complete set of drawings.

Sep 10, 21 12:50 pm  · 
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Cool, to avoid confusion re: the flashing reciever, I'd recommend showing a really simplified dashed line or something to represent the flashing receiver and any cladding in this detail. Then add a callout to direct them to those other details. Let those other details show the detail for the receiver and the cladding types.

Sep 10, 21 1:00 pm  · 
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Almosthip

Thanks Tips

Sep 10, 21 1:26 pm  · 
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