Cutting metal roofing

[gregs]

Possible project coming up. Have a steel building that the ends of the metal roofing sheets are rusted thru at the very edge in spots. The rest of the panel is good. I have some spare sheets of the same metal roofing leftover from the build. One solution I was thinking about was to cut the existing panel off about 2' from the end. Cut a piece long enough from the extra panels to slip under the existing roof back to the 2nd purlin (aprox. 4'). Add some sealant at the cut area, then rescrew everything back down. My thoughts are that it would allow me to replace sections while keeping the building in use. Be able to work around weather and other conditions, etc.

I have worked with metal roofing before and its always been a pain to cut. Wanted to see if anybody had a good tool or solution to make it easier. This is the heavier 26 gauge panels btw. I was thinking of some type of circular saw that I could run along a temporary fence attached to the roof. Maybe dedicated to cutting metal? Correct blade? etc. If it was quieter that would be a real bonus.

 

[Gummi Bear]

My experience with metal roof is building loafing sheds and barn type structures, so take this with a grain of salt. Usually R panels or corrugated tin.

I've used a regular blade turned around backwards in a circular saw, and it works ok. A couple of years ago, I ponied up a few bucks for a metal cutting blade for my circular saw. It works much better. I think it's this one: https://www.homedepot.com/p/DIABLO-...l-Cutting-Circular-Saw-Blade-D0770F/203162379



With R panel, flipping it upside down is definitely easier to cut (with the tall ridges facing down). If you're trying to trim existing roof, maybe look at making a chute board (a low tech version of a track saw) that you can clamp or screw to the panels to help keep a straight line. https://www.finehomebuilding.com/2010/11/11/make-a-saw-guide-for-faster-cleaner-cuts

 

[theoldwizard1]

Power hand held shears.

 

[fitter30]

Small 6" angle grinder with a thin wheel

 

[gmcgeo]

Power shears

 

[gregs]

Its like a R panel with tall ribs. Not sure what type of power shear? Would you be able to use it on existing attached roof?

 

[Sumboodie]

Skill saw with the blade backwards is all I've used.

It's LOUD, wear ear hole pluggers!

Grinder would work, though if you dwell too long, it'll burn the paint.

 

[racecougar]

I used these shears when skinning my building, but I expect they would be a real pain on metal that is already installed/screwed down. I'd go the circular saw route.

ONE+ 18V 18-Gauge Offset Shear (Tool Only)

 

[gregs]

Looking at the metal cutting circular saws. They appear to operate at a lower rpm. Probably better for noise and chip throwing. The good ones are rated up to 5/16 plate. So I could stack my "new" sheets together and cut multiple pieces at one time. Thinking I could make a guide with a piece of angle iron or something like that and screw it to the cut side on the roof. Maybe do 12' at a time. Just spit balling right now.

 

[stingry]

I use the Milwaukee corded metal cutting circular saw. Pricey but works well. I see they now have a smaller cordless model, may be worth a try.

 

[landrover bodger]

plasma cutter is what i used on mine

 

[racecougar]

plasma cutter is what i used on mine

That isn't going to be much fun up on the roof. Not to mention the risk of setting the building on fire.

 

[landrover bodger]

i

That isn't going to be much fun up on the roof. Not to mention the risk of setting the building on fire.

i was just cutting the overhang off so the rainwater ran into the gutter .

 

[Olafur]

Yesterday I met a buddy who was helping his brother in law replacing a metal roof. He was amazed some guy came with his circular saw and some good or "special blade" and they cut all the corrugated metal with it like "butter" he said. Best invention since the wheel he said.

Possibly the same solution as mentioned in post #2.

 

[rustyjames]

Metal cutting circular saw against the ribs and power shears for cutting the lengths.

 

[jubilee]

I use a 7 1/4 “ circular saw with metal cut off blades. Buy the blades at Lowe’s. Believe they’re 1/8” or 3/32” thick.
Slices right through. Fence with 2” x1/4” flat and clamps.
I tried the backward metal wood saw blade ONCE. Loud, slow, and the whole panel got hot.

 

[nadogail]

I like you plan to save as much of the old panel as possible and splice in a new section.

 

[gregs]

I looked at the Milwaukee saw and a couple others similar to it and think that’s what I would use. I think the plan is a good one to save the majority of the roof sheeting since it’s a 60’ wide building. My next problem to overcome is dealing with the insulation when trying to slide the new piece under the existing. It has the typical vinyl faced metal building insulation. The section where the leaks are is in poor condition and will need to be removed and replaced with something. Not sure if I can pry up on the panel and get it to slide under without pushing out the insulation.

 

[TTMotorsports]

I have used one of these and it worked good. BUT i already had one so it wasn't a new buy for me. I would put a metal blade in a circular saw and call it a day

Eastwood Mini Metal Saw

Compact Metal cutting circular saw that is powerful enough for cutting of rebar, conduit, sheet metal, tubing and plate.

www.eastwood.com

 

[jrsavoie]

Yesterday I met a buddy who was helping his brother in law replacing a metal roof. He was amazed some guy came with his circular saw and some good or "special blade" and they cut all the corrugated metal with it like "butter" he said. Best invention since the wheel he said.

Possibly the same solution as mentioned in post #2.

Can you get details on exactly which blade and tooth count?

Trial and error can get pricey, both in blades and wasted material. Not to mention wasted time.

I've had the 8" Milwaukee electric saw and the 6-1/2" V18 for decades. I was looking to get a new M18 steel cutting circular saw last year, but it seems they downsized the blade diameter.. For me, the 6-1/2" has been the perfect diameter. I bought a v18 to M18 adapter and am using my old V18 metal cutting circular saws.

 

[Metallitubby]

Eastwood Mini Metal Saw

Compact Metal cutting circular saw that is powerful enough for cutting of rebar, conduit, sheet metal, tubing and plate.

www.eastwood.com

Man, I don't need this tool, but damned if I don't end up buying it just because.

 

[txvwnut]

Circ saw with blade in either way will cut roofing metal just fine. The big issue is stacking the panels will cause a moisture issue between the two panels creating a bigger issue.

 

[mcbane]

I did a corrugated metal roof using a metal cutting carbide blade in a 7-1/4" saw. Works great but there are a couple things to watch for: 1) Steel cutting blades intended for sheet metal are different than the blades intended for cutting 1/4" plate, so read the packaging before buying the blade and 2) every steel cutting carbide blade is sensitive to cutting velocity, or how fast the tooth moves through the metal. That is why dedicated metal cut saws have a smaller blade diameter and/or lower blade rpm - keeps the cutting velocity reasonable.

In my experience, the old style worm drive skillsaw runs slow enough to keep metal cut blades cool and make them last a really long time. My direct drive (and way lighter) 7-1/4" saws spin the blade too fast and cause the blade to lose teeth after any heavy cutting.

 

[Jackfre]

My shop is core ten corrugated sheets for the walls. We used a standard circular saw with the think abrasive blades. It was a giant pitn. Noisy and sparks. The abrasives are cheap. They wear quickly. I have an Evolution 14’ chop saw and see that they have a metal cutting circ saw. If I get into another corrugated project I will have one of those.

 

[gregs]

Circ saw with blade in either way will cut roofing metal just fine. The big issue is stacking the panels will cause a moisture issue between the two panels creating a bigger issue.

I really dont see an issue with overlapping the panels shingle style. I have seen buildings where the panels where done in multiples due to the length. Probably going to be 12"-18" overlap. Depending on whether I can lift the panel, I was thinking of adding a sealant near the edge. Also thought about using a roofing tape like Eternabond, but that may be overkill.

 

[gregs]

Definately leaning towards a slower metal saw. No point in trashing my Hitachi circular saw.

 

[FMB4]

Apply the good panels over the bad and be done with it.

 

[jmdirk]

Definately leaning towards a slower metal saw. No point in trashing my Hitachi circular saw.

They're definitely nice, and not badly priced. Check out the Evolution brand I have their 10" mitre saw and the 7-1/4" circ saw. With their general purpose and metal cutting blades they'll go through that quite quickly. I've cut 1/4" plate with the circ saw. But make sure your pant legs are over your boots cause metal chips will fly

 

[Supa Dexta]

Nibbler.

 

[Robinson1]

Grinder with the thinnest abrasive cutting wheel you can find. Like cutting butter.

 

[23ford]

7 1/4 skil saw with lade turned backwards

 

[19D2P]

All of these methods will work. Some will create a level of heat that will "possibly" damage the finish of your panels. I am guessing this is what damaged the panels in the first place.

If I was in your shoes I would use a nibbler and give the roof the best opportunity to live up to it's potential life expectancy.

 

[gregs]

Actually I think the problem was caused by the way the brackets for the gutters are attached to the roof. Its a flat bracket that was laid on the the roof and screwed down, with no sealer. Over the years water seeped in around the screws and saturated the insulation and eventually rusted bigger holes that let more water in and caused more rust. So along with fixing the roof, I need to relocate the gutter brackets as well.

 

[quattro_sinko]

Interesting that they rusted up from the bottom. A buddy of mine rolls and supplies metal roofing, I believe it's referred to locally as "Ag", "ribbed", or "barn roofing". He has talked about the cut end at the eave of the usable panel being the area most prone to rust, and we have discussed putting some kind of sealer on the exposed metal. While I have never done so, it's sort of still at the forefront of my mind. I rarely install any roofing, at this point it's probably been 4 years since my last metal roof (a porch), but in all I've probably installed 10 in the last decade.

I would also maybe investigate a little more to see where you want to seal the panel: I'd likely put thin butyl tape between the vertical seams, but if you want sealant horizontally under the old cut edge to the new panel I might look and see what recommendations are from manufacturers. If you're overlapping 48"I don't know that you would want to trap any moisture between the panels should any condense or penetrate through and end up between. Possibly seal it horizontally at the top of the replacement sheet? Might be good to seal, might be bad, but either way I'd probably look at what is spec'ed and think about it some more. I'm sure others will chime in.

As far as cutting it? Are you breaking the old material on a purlin? A dedicated metal blade in a sidewinder or worm-drive woth some kind of temp fence is the way to go, IMO. I would occasionally toss a metal blade in my table saw for long pieces, and it worked OK, but it made a large face shield MANDATORY if you were on the feed side (protip: make sure it covers your throat, too. Oh yeah, you will want a helper on the outfeed, also.
My pneumatic nibbler works great for cutting shapes, but I've never been satisfied using it for long, straight cuts. Same with powershears.
Cut off wheels scorch the panel too much for my liking.

Good luck.

 

[Daniel Dudley]

You can cut a whole stack at once with a 40 tooth carbide blade and a saw guide. Put the guide in the regular way, use the guide to hod everything down, and go slow. I often use a saber saw with a very fine metal blade for cutting roofing. It is quicker than you think. Nibblers are good too. HF has a cheap power shear now, but I have only used very expensive ones. Might be worth a shot.

I'll do a lot of things with proper face protection.

 

[NUTTSGT]

plasma cutter is what i used on mine

When I put ribbed siding on the one wall, all I have done so far, I used my plasma cutter to cut out for the outlets. Slick as cutting butter.

 

[gregs]

The overlap will only be 12 to 18 inches. My plan would be to cut the old metal just past where it lands on the 2nd purin maybe 6 to 8 inches past. Then when I slide the new piece under it, it will be supported by the 2nd purlin and first purlin. I'm sure the gutter brackets are where the rust started as thats where it is the worst, and once the insulation got wet it just spread from there.

Since I'm only replacing the last 3 to 4 feet it shouldnt be to hard to cut a stack of replacement pieces and would only need 2 ripped narrower for the beginning and end.

 

[lukel99]

Seconding the Diablo circular saw metal cutting blades. The one they sell in-store at HD is meant for thicker metal, not thin sheet, and I find that it dulls pretty quickly (within 30-50 cuts) but I went back and bought them over and over when building my garage because they beat anything else I was using.

I also used one of these: https://www.homedepot.com/p/RYOBI-O...dless-Compact-Cut-Off-Tool-Tool-Only-PSBCS02B and it was great for things like notching thick metal studs quickly on the job, but I wouldn't use it for long cuts.