Metal roof frustrations

[Cord]

Have an existing garage with a shingle roof that is well past due for replacement. Building measures 22x26 and has unequal roof pitches on either side. Front is 12:12 and the back is 9:12. Tore the roof off and replaced the one plywood sheet that was holed when a tree fell on the garage. Grabbed the fabricated gutter apron and noticed that it was bent at the wrong angle. Company bent the flashing to be plumb when I needed a 90* bend because the fascias were not plumb. Rented a sheet metal break and bent them to the right angle. With the apron installed I now located the center of the eave and the center of the ridge. Calculated that the metal roof panel (5v) needed to be shifted over 6" so the rake edge flashing wouldn't land on a rib. Check. Installed the first panel and noticed that it wasn't square to the eave. Installed the second sheet and things were really out of wack. Pulled the second sheet and loosened the first one. Set the first sheet square to the eave and it was 1.5" from my center mark. WTF? Double checked my measurements and they were good. Pulled a string along the eave and noticed that it had a 3/4" bow. Because the 3-4-5 triangle was pulled off an arc I threw out that location. We ended up going with the original location but I had this suspicion that things still weren't right. When we were installing the panels I was at the ridge and she was at the soffit. This way she didn't have to get up on the roof. Unfortunately it forced me to rely on her for the drip overhang dimension. Worked through the day and finally set the last panel as the sun was setting. Done! As I was screwing down the last sheet I noticed that the gap at the ridge was getting pretty wide. Wide enough that I wasn't certain the ridge cap would cover it. Climbed down and looked at the drip overhang. Clearly something was wrong. The side we started from had a 1" overhang, the last panel had a 3.25" overhang. F$^&! Turns out the mrs had been aligning the panels but then didn't check the dimension. Even reminded her to do this several times. A whole day wasted and now I have to pull all the panels.

 

[/pine]

With an out of square rake you have to "split the difference"...

Try squaring the first panel with the far end of the rake...it may be that each subsequent panel will have to be slightly off so when you get to the last panel the reveal at the eave will be the same as the first...i.e., 3.5" divided by the number of panels...

Try imagining/picturing all the panels assembled perfectly square and overlaid on the roof rake...and what it will take to adjust for the out of square roof...

 

[boggen]

if your panels are long enough, purposely leave extra over hang at the bottom. and if your panels are long enough, account for some extra over hang at the ridge.

you can go back with a circular saw, with blade reversed, to cut the extra off. wear.... long sleeve shirts, pants, gloves, face mask, and eye protection, when cutting if possibly lots of little metal shavings! and a lot of sharp corners. the shavings can end up being like bee stings they get so small. so be careful.

for gutters and like, don't nail the very bottom down ya leave a foot or so un done, so you can slide stuff up under neath it. once you cut the excess off. though if saw is giving you trouble you may have to temp nail / screw say a short scrap 2x4 here and there, to hold the metal from flapping around on you, until after you get things cut.

 

[/pine]

...you can go back with a circular saw, with blade reversed, to cut the extra off...

IMO this is not a viable option...reversing a wood cutting blade will work with aluminum (to some degree) but not with galvanized steel....a much better choice would be an abrasive blade or a steel blade made for cutting steel...also a cut edge will rust much faster...

 

[kubotacres]

IMO this is not a viable option...reversing a wood cutting blade will work with aluminum (to some degree) but not with galvanized steel....a much better choice would be an abrasive blade or a steel blade made for cutting steel...also a cut edge will rust much faster...

I thought the same thing. But after going through a cutoff wheel every 2-3 sheets and at $8 a pop its expensive. The reversed blade cut my galvanized metal straight and easy. Not to mention it cost nothing and lasted through over 20 sheets of tin.

 

[/pine]

I thought the same thing. But after going through a cutoff wheel every 2-3 sheets and at $8 a pop its expensive. The reversed blade cut my galvanized metal straight and easy. Not to mention it cost nothing and lasted through over 20 sheets of tin.

Can't argue with good results...perhaps my experience was with heavier gauge panels?

 

[roadhunter]

IMO this is not a viable option...reversing a wood cutting blade will work with aluminum (to some degree) but not with galvanized steel....a much better choice would be an abrasive blade or a steel blade made for cutting steel...also a cut edge will rust much faster...

Don't cut the bottom edge with a saw or you will have rust. Cut the top and hide it with the ridge.

 

[/pine]

... Cut the top and hide it with the ridge.

This can be a challenge if the eave is not square with rake edges...unless you don't mind possibly having to cut the last panel out of square to fit the rake edge...

 

[Barnbuilder]

Did you measure your diagonals? On roofs that are way out I'll pull a string across the bottom where I want the edge of the metal so I have something to square the metal to. I like to use the 3' wide panels. They are easier to stretch and squeeze to make the eaves fall out closer.

I don't like using a saw because it can get the metal hot and burn the paint. Alot of manufacturers don't recommend using a circ. saw.

 

[boggen]

*scratching head* i realize i am no pro or anything. but i think the rust part is getting carried away? no standing water, metal is sloped for water to run off, nice clean cut, and not all jagged from tin snips, and if there is a little burr its not that hard to take a pair of pliers and twist it off. maybe i am off. *shrugs* it what gramps, dad, uncle, myself, done on metal sheds here, granted been a good amount of years. but there hasn't really been any new technology to make large differences?