Cutting existing metal roof


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Old 04-11-22, 09:25 AM
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Cutting existing metal roof

Hello All, I have a 12x24 run-in shed with a metal roof. The roof is slanted from the front to the back (not peaked). The back side is the low side.

It's the back side I have put a rain gutter on. Even with adding a 2x4 thickness to the back panel, the rain gutter just barely juts past the edge of the roof by an inch or less. The gutter will only catch the rain water in a light drizzle. If it rains medium, the water will flow off the roof and by-pass the gutter.

I now have to get up there and cut the roof edge back about 2-3". Once I have cut the 30' of metal back, I'll be left with a raw edge and am worried about rust. Is there something best suited to be applied to this edge? Rust inhibiting primer with a rust inhibiting outdoor paint over that? Is there something better I should use?

Also, cutting the edge (I'm 69 yo woman) I'm wondering about the best way to do that. I'll be using a skill saw but what kinda blade? I've seen where turning a cutting blade backwards works but so does a grinding (?) blade (I used this to cut rerod once) -


Ignore what is hanging below the gutter.

have not added the downspout yet, today.

ideas?
 
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Old 04-11-22, 09:34 AM
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Not only is the roofing too long but the gutter is WAY too low. Even if you cut it off, a decent heavy rain will still overshoot it.

You would be better off taking the gutter down, remove all the fascia, sister some framing onto the sides of the rafter tails (plumb cut all the ends and use a string line to get them all straight as you nail them on), then add a new (plumb) fascia onto the front of those rafter tails. The front of that fascia should be about 1" behind the front edge of the metal roofing. Slip a metal drip edge between the roofing and the top of the fascia and screw it down. Then slip your gutter up under that drip edge as high as it will go. The metal roofing will then direct the water right into the gutter.
 
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Old 04-11-22, 10:10 AM
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It does have a metal drip edge. I put the treated 2x4's immediately below that drip edge.

Maybe what I should do is take the gutter down. Cut the metal roofing back to one inch over the drip edge. Take all the screws off the drip edge (you can see it in the middle pic) and slide the gutter up under that?

I live in northern michigan and we get a lot of snow and ice. I wanted the gutter below where the snow/ice would travel off the roof when it melts and lets go. But I see that it may be way to low.

I cannot remove the fascia and sister framing onto the sides of the rafter tails. Beyond my abilities. I have a friend who is close to the same age as me and could not do it either and has very limited time to pop over and help.

So it's me that has to do it and she helps with holding stuff.

I was trying to avoid cutting the roofing but I see that it must be done.

Any ideas on best way to trim it down? One inch beyond the fascia?
 
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Old 04-11-22, 12:20 PM
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sister some framing onto the sides of the rafter tails
You got a solution but it's different from what your inquiring about but end result will be the same.

Build out the fascia more rearward so the roof metal doesn't direct the water over the gutter. Much easier than trying to cut the metal roof back!
 
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Old 04-11-22, 12:30 PM
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Maybe what I should do is take the gutter down.
Maybe what you should do is take the gutter down. Forget about your existing drip edge that is too long and too far back to do any good. Remove the wood you currently have installed. Add as many layers of 2x6 to the front of your fascia as you need to, to build the existing fascia out until it is 1" from the front of your existing metal roofing. Put those 2x6 right on top of the existing drip edge... and as high as possible... tight to the metal roofing. Then slip a NEW drip edge in, between the metal roofing and your new 2x6 fascia. Then raise the gutter up so its under that drip edge and so that water has a straighter shot into the gutter, with no chance of overshooting it. And no cutting of the roofing required.

By the way, treated wood eats aluminum, so if your gutters are aluminum that's a bad combination.. if they are steel, it may still corrode but as long as the paint stays intact it's okay.
 
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Old 04-11-22, 02:13 PM
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The gutters are aluminum. XSleeper this latest is something I can do. Thank You.

Will purchase more, shorter, drip edge. By doing your suggestion and building the fascia out to 1" from roof edge, would using 'non-treated' 2x6 boards work?
 
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Old 04-11-22, 04:15 PM
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As long as you paint them, they should be fine. Cedar would be best but it's a little pricy to be using on a shed. Course everything is pricy nowadays.
 
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Old 04-11-22, 07:47 PM
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Why not pull the gutter, pull the 2x4's and then cutting the roof back to 1" from the existing facia. I could snap a chalk line and run a skill saw along cutting the roof back. Then, pulling the existing drip edge and putting a 1" deep drip edge in place of it. Put the gutter under the 1" drip edge.

There is *****athane that goes from the bottom of the existing drip edge now and goes up under the roof about 3-4'.

This way, no additional cost in boards (30' x 2x6's would mean at least 6 boards at 10' length), no painting. Just cutting the roof line. Only additional cost is the 1" deep drip edge. No worry about painiting etc.
 
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Old 04-11-22, 08:04 PM
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If that's what you want to do. This is the sort of blade you would use. $40. And don't put it on backwards either.

Rusty metal primer and some Industrial farm enamel spray paint on the cut edge..

You might want to screw a 1x4 to the scrap side of your cut (lay it on the roofing and screw it down) to give you something smooth for the skilsaw to ride on.
 

Last edited by XSleeper; 04-11-22 at 08:20 PM.
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Old 04-11-22, 08:28 PM
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Oh, excellent! Thank You.
 
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Old 04-22-22, 05:28 AM
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XSleeper, I purchased the blade you suggested from Home Depot. Hoping to get to the project this week if weather permits.

The blade in the center states 'do not knock' out but 'twist out'??? I don't know what this means, blade is still in package.

 
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Old 04-22-22, 06:07 AM
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It's been laser cut around the hole such that it's held in place by a thin piece of metal, insert something metal into the hole at twist, it will break off.

You sure you need to remove it??

BTW for very thin metal this would be a better choice, that blade is pretty aggressive for thin corrugated metal.

https://www.homedepot.com/p/DEWALT-7...3511/202579870
 
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Old 04-22-22, 06:16 AM
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You only remove that diamond knockout if you are using a worm drive skilsaw that has a diamond arbor. If you don't have a diamond arbor you use it as is... a 5/8" round hole is what is common on most other "sidewinder" circular saws.
 
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Old 04-22-22, 07:23 AM
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I have what I believe is a circular saw that uses a 71/4" blade. I probably don't need to remove it, just never saw the option before. Probably take it back and get the grinding blade your latest suggestion. Thank you.
 
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Old 04-22-22, 07:34 AM
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Abrasive blades are slower and burn through the material. A ferrous carbide blade cuts faater cleaner and cooler and is the best blade to use on roofing. You can certainly use if you want but wear goggles... not just glasses. I have had to go to the emergency room TWICE to get a piece of black abrasive ground out of my eye.
 
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Old 04-22-22, 07:55 AM
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Well, now that you've said that about ferrous vs abrasive blades, I'll stick to the diablo steel demon. It says on it "For very thin ferrous metals".

I also have a full face mask with breathing gizmos on each side that I plan on using along with covering my neck & arms for protection.

Another thing I'm concerned about is as I cut, the weight of the 1x4x8 + the cut off metal part is going to sag as I go along. Thinking using duct tape? to hold it up or creat a slight sag at the least.
 
 

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