Framed Chimney Chase and Flashing Details
I am a homeowner from Wa. County, Oregon so climate Zone 4c looking for advice on flashing detail for a framed chimney chase. We have just had a gas fireplace installed and inspection hopefully on Monday then we can start to button it up. Chase is on the gable end of a single story home. The chase will be clad with cultured stone (lumpy stucco) so we want to make sure we get all the flashing details right. While I have a lot of questions I’ll start with the most pressing first.
The plywood Not OSB) has 1/8” gap between seams in the field and on the corners (inside and outside corners). I could use a peel and stick flashing membrane like Vycor as its readily available on all the corners and sheathing tape on the field seams but I was thinking it might be easier and a better result if I use Prosoco fast flash on the corners and and seams. It won’t peel away or come undone and it looks like something a homeowner can accomplish. I can also get their joint and seam filler.
Question #1 – Should I just use the fast flash or treat all joints with the joint and seam filler, then the fast flash or would a peel and stick be better for a DIY’er? Yes I would have to buy a sausage gun but probably only 2 tubes of the fast flash and 1 tube of the joint and seam filler so I’d be into it for maybe $150.
This chase will have sloped shoulders and since anything that isn’t vertical is a roof I will need to treat these should as such. They will be capped with hearthsones. Trying to figure how to incorporate the wrb and what to do on the shoulders.
Picture shows yellow area where I would use fast flash, blue is wrb and red is ice and water shield on shoulders and over wrb with succeeding web layers shingled properly.
Question #2 – Even though Vycor is a non-roof flashing would it be acceptable to use on these shoulders or must I use an actual roof underlayment like ice and water shield? The shoulders measure 23” x 17” so not more than 8 sq feet. I am going to need some for the roof to wall transition anyway. I can get a 108 sq foot roll of ice and water shield for $100 or a 150 sq ft roll of GAF Weathermate for $60.
Any comments or thoughts would be greatly appreciated.
Thanks for your time! KJ
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