I plan to use GAF Timberline HDZ shingles (fiberglass asphalt) when my house is reroofed. What would be the best dimensions for the step flashing? Would a 5"x5"x8" size for step flashings be good? The shingle dimensions are 13-1/4" x 39-3/8" and exposure is 5-5/8".
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All the dimensions you've just quoted are for thickness. The dimensions in your question are about area (length x width). Your other question is about thickness, so I presumed this one was about area only.– FreeManCommented Oct 20, 2023 at 19:05
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For a ballpark, is it unreasonable to think typical 2-story ~5000 SF house might not need >3 boxes of step flashings? (250/box, each 5x5x10" piece will overlap ~2" to cover ~3" distance) I realize sloped roof-sidewall intersections would be longer than corresponding ceiling-wall intersections so I intentionally doubled lengths of all ceiling-wall intersections under the roof-sidewall intersections to overestimate, then totaled for overestimated needed coverage distance and got 2112", which I divided by 3" per piece = 704 pieces. 704/250 per box = 2.81 boxes.– JessiCommented Oct 20, 2023 at 21:04
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I am also interested in thickness too, I would rely on a contractor to use right method to determine # boxes. I don't want to bother them to figure that out just so I can do price comparison between standard thickness step flashing and 0.018" thick. However, I need to let them know which thickness I want before they figure out the estimate which is hard to know if I have no clue how many boxes I need. The difference between 3 vs 4 boxes of upgraded cost won't likely make a difference, but 6 boxes of upgraded might. I am hoping 3 or maybe 4 boxes would cover the roof, with a little to spare.– JessiCommented Oct 20, 2023 at 21:26
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I was interested in answers to both questions No one answered the other one, so I figured I'd ask you here. I'd rely on a contractor determine number of boxes actually. I don't want to bother them to figure out a price comparison between standard vs 0.018" thickness, but I was supposed to let the know what I want to be included on estimate. A local roofing wholesaler who I know the contractor uses can order the 0.018". Of course they won't tell me the price difference, but I figure if it is just for 3 or 4 boxes that might be tolerable. If it is for 10 boxes, probably not.– JessiCommented Oct 20, 2023 at 21:49
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1 Answer
Disclaimer: I am not a professional roofer.
I did the flashing on my roof when I built a garage 30 years ago. I used whatever pre-formed flashing was available at my local hardware store without a second thought. There was only one option, so I used it. I don't know the dimensions nor the thickness of the material I used it was simply, "pre-bent aluminum step flashing".
I had one location leak because I didn't properly take care of the siding on the wall above the flashing, but I never had a failure of the flashing itself.
IMHO, I don't think size nor thickness will matter in the long run, so long as what you do use is properly installed.
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Yeah, use two or more per shingle course if necessary. Thickness doesn't much matter as the shingles will fail first. It's almost not worth thinking about. Commented Nov 20, 2023 at 14:02