I’m installing a metal roof ( R Panel ) over exsisting shingles.
The roof has 2 valleys that terminate 8′ from the edge on a 2/12 slope. (See Pics)
The detail I plan on using now is to fab up a pan that goes under the valley flashing and extends to the edge of the building.
I then plan to cover this pan with the lower panels. So it will drain under the R Panel.
Has anyone encountered this before? Any suggestions or hazards I need to be aware of? Better ideas??
I plan to use Grace I & W for the valley and pan areas.
All lower panels will be duckbilled and sealed before adding flashing and upper panels.
Replies
are you the same guy who has a thread on changing metal roof to 1-1/2 / 12?
what is R-panel?
I'm not sure I would like to do that roof with some kinds of metal roof panel.
But I would see it as using a pitch change valley that empties on top of the lower pitch AT the hip junction. It's a touchy spot for metal
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R Panel is the common name in my area. http://www.corrugatedind.com/indR_panel.html
Someone else was talking about the low pitch thread, although this is a simular situation.
Instead of emptying the valley onto the lower panels I was proposing running a drain pan under the lower panels.
Any way I cut it, it's going to be tricky to drain it properly
Sounds like reverse lap to me, not a good idea. You need to address the lower pitches first (although they appear too low pitch for the types of metal roofing I have used). You need pitch change flashing at the top of the lower pitch--bottom leg of that flashing goes on TOP of the lower panels. Your valley metal goes on top of the pitch change flashing. Your upper panels go on top of the valley.
Stripping the existing roof would be a good idea. Why leave it?
David
Sounds like reverse lap to me, not a good idea.
I'm not sure what reverse lap is.
I understand the bottom panels need to be addressed first. Draining that valley on the top of the lower panels makes for a nightmare of a transition and flashing sealing.
As far as stripping the whole roof.......labor saving for me....... I don't see it as detrimental by leaving existing shingles. I'm screwing PT 1x4's 2' OC for the whole roof. I'll strip and use I&W on critical areas., Valleys, roof curbs, hood blowers etc.
After seeing the type of panel, I am definitely shying away from it for that roof. You would certainly need to back itr up with ice and water shiled
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I concurr 100% with that opinion. Leak-factor aside (did I really say that??!) just detailing those hips and valleys to look decent is gonna drive him nuts.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
>I'm not sure what reverse lap is.
Whatever is above has to lap OVER whatever's below.
This is what I was reading:
>I then plan to cover this pan with the lower panels. So it will drain under the R Panel.
From that sentence it sounded like you were going to tuck the valley metal under the lower panels. Maybe I was reading wrong, it wouldn't be the first time.
Hips, valleys, low-slope, pitch transitions.... This is a bad candidate for metal.
Strip it and re-do it with shingles. Cover the entire low-slope section with I&W. All that will still cost less than a steel screw-down layover.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
Hips, valleys, low-slope, pitch transitions.... This is a bad candidate for metal.
Strip it and re-do it with shingles. Cover the entire low-slope section with I&W. All that will still cost less than a steel screw-down layover.
This may very well be my solution. I prefer metal over shingles by 100-1 but it may not be the answer in this case.
Even with shingles this screwy hip makes for a bad leak area.
I got a few pieces of metal I'm taking up on the roof this afternoon to see if I can wrap my head around a solution.
I've thought of going with a hybrid--part metal/ part shingles... we'll see.
Thanks all for your input.
Ray
Boats234,
I am glad that someone else gets krap like this to do. At least you don't have a chimney in the valley and pitch break like I did.
We order unformed panels as flashing. We get 4x10 sheets so I can put it in the break. Use it at the pitch breaks.
I only see one little tricky spot where a lower panel has to be slit for the valley to exit. Don't know how to explain better.
How are you gonna seal the screw holes in the fabbed pan? Be hard to double washer those.
KK
KK
After further thought and piecing some panels together, I'm giving up on the idea to drain the valley under the lower sheet.
It would be the cleanest looking method IMO, but it also would be highest likelihood of hidden problems.
You still looking to move west???
It sounds like the opening day of duck season here every morning with all the nail guns going off.
Every hotel room in town is full with outside contractors...... probably last for 2 more months.
Ray
All I can say is I'm glad it's you and not me. No way I'd try to put R panels on that. Good Luck.
View Image
Why not go to standing seam and use the valley pans and hip/ridge covers and get a "real" metal roof? The pitch change can be handled with a transition and Z metal and the valleys are a piece of cake - as long as you can read a tape and cut and bend the sheets.I would not drain the valleys under the low slope - you are asking for trouble IMO.It isn't the easiest but it's only steel - you can out-think it!
Whatchu think??? 20oz. flat seam sucked down to every contour? ;-)
Damn Grant, you were my ace in the hole to come up with an easy solution.
I took some panels up on the roof on Friday afternoon. I may have to custom bend a lower panel without the center ribs to make it work.
It was hot and my head hurt after an hour..... so I spent the next 45 minutes looking down the shirts of the women coming into the bar for happyhour.
Bad thunderstorm hit Saturday night and tore some tarps off.....turned roof damage into ceiling damage....Oh well, need to get my butt in gear.
Ray
I may have to custom bend a lower panel without the center ribs to make it work.
That's the answer. Trying to shoehorn pre-made panels into that would make my head hurt. If you could lock your roof panels into the valley, rather than overlaying them, you'd be better off. But I don't see how that can be done with R panels.
I'm concerned about the unequal pitches on either side of the valley. Water is going to want to shoot under the low pitch side from the high, but you've got greater volumn on the low side. It's a tough one.View Image
My solution.
I had a lower panel custom bent to remove the 2 center ribs (pic #1)
I fit the panel in place followed by the valley.
I cut an R panel sheet and overlayed the valley and top of the pan (pic #2)
I was concerned about the 7/12 roof draining past the valley flashing on the lower 4/12 portion, so I custom bent some galvelume into a step flashing of sorts.
The step flashing locks into the valley hem, then I bent a leg up 3/4" that will fit under the 1" rib of the roof panel... I also have "Em seal" along the valley.
I put a few strips of I&W on the galvelume where I might have a fastener penetrate just to be safe.
Ray - I'd say that'll probably work since you don't have ice dams in your neck of the woods. Looks good.View Image
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