Flashing Detail for Frontispiece above Entry Door


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Old 09-10-07, 07:21 PM
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Flashing Detail for Frontispiece above Entry Door

I'm in the process of rebuilding the front of a colonial style townhome and have rebuilt a rotted frontispiece that sits over the door. The piece is triangular in shape and has 2x6's that make up the "roof" of the detail. The existing flashing has rusted/corroded away, therefore I'd like to replace it with the non-corroding white PVC roll flashing. I've selected the roll since I need to flash the 6 inch depth as well as create a vertical flange to slide up behind the Tyvek that will be installed. I can't find pre-shaped flashing in this size.

I need advice on how to properly install the new wooden frontispiece as well as how to properly flash afterwards. The main questions I have are:

1) Since plywood is being installed first, should the frontispiece be screwed directly through the plywood and the Tyvek cut to fit around the piece or should I install the Tyvek first, install the frontispiece and cut slits along the upper edges to slide the flashing up behind the Tyvek?

2) The top angle of the triangle that needs flashing is 120 degrees so I first have to break the roll flashing to a 90 degree angle, but then I must cut the vertical flange down it's full height to bend the flashing to fit the 120 degree angle. How do I then flash the cut I had to make in the vertical flange? Is there a better way to flash than what I described?

3) Is the PVC roll flashing a reliable material or does it quickly degrade? Should I go with another metal material and break a piece to the shape needed?

Thanks in advance to anyone that can answer any of the three questions.
 
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Old 09-10-07, 08:02 PM
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1). I'd install the Tyvek first to completely cover all the sheathing. Any trim details can be mounted on top of that. Once trim details are installed you can slit the Tyvek about 1" above the trim and tuck your flashing behind the Tyvek. The slit in the Tyvek can be taped to the flashing with either Tyvek contractor tape or any of the butyl rubber based peel and stick flashing tapes that are out there.

2). If you are referring to the "V" shaped notch that you would create by cutting the vertical flange and then bending the horizontal flange 120 degrees, I'd put a dab of sealant at the bottom of the V, then cap that with an additional piece of flashing that is maybe 12" wide and 4" tall, that is cut like a ^ on the bottom to cover your side angles.

3). If you are referring to PVC coated aluminum trim coil, it will hold up fine. There is also coil that is purely PVC (Pro Trim). Either would work.
 
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Old 09-11-07, 09:31 AM
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Thanks for the advice XSleeper, what you recommended was close to what I expected. I didn't realize they made a pvc coated roll stock. I'll have to research that option.

One follow on question to the solid pvc roll stock. When installing directly to a wood structure, I see nailing or screwing being an issue since it opens up many locations for water to infiltrate. The pvc is rather flimsy, especially in a six inch extension over the frontisepiece I'm installing. Is it best practice to bond the pvc flashing with a butyl or acrylic caulking to the wood structure or is there an alternate method?
 
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Old 09-11-07, 05:12 PM
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Your flashing could be bent like a drip cap... With a vertical flashing (against the wall, behind the Tyvek), the horizontal part (or perhaps slightly sloped so that water will drain off) and then another vertical part that bends down over the front 3/8" or so. Having a bend on the front edge will give the piece a little more rigidity and it will likely lay down better.

You could apply sealant like Vulkum to the horizontal parts so that you only have to nail the flashing to the sheathing in a couple places. I imagine that aluminum flashing would be a little more stiff... never actually worked with the vinyl. I bet the lip in front is the key either way.

If the downward bend in front isn't acceptable, you can bend a hem (a 3/8" complete bend that is then crushed onto itself) which will also help make that long piece a little more stiff, which will help it lay flat. The angle you bend the back side is also important. Having a little tension on it will also help it lay flat.
 
 

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