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Lars 09-20-2009 07:06 AM

Cutting METAL roof.
I know this is not exactly an oven question, but there are many creative builders on this forum, one of which, may have an answer.

I got some LONG pieces of metal roofing that I would like to cut into 6' pieces to make a lean-to type wood shed. (Okay, I guess this is connected to wood fired ovens after all)

The metal is corrugated so I can't get my electric ( sardine can style) cutter up and down the, roughly 1.5 " sine wave bumps. I may have to use a (ugh) abrasive blade...

If so, what blade works best and is there any shortcuts to the ridiculous noise and sparks and flying hot metal bits?

shuboyje 09-20-2009 07:42 AM

Re: Cutting METAL roof.
I do this stuff everyday for a living, and have yet to find a way around the sparks and noise. If you have an angle grinder, or are willing to spend $20 for a cheap chinese one I would go that route. Regardless you want standard thin abrasive cutoff wheels. Let the blade do the cutting, don't force it, and you will save lots of money in blades. If you try and force it and go too fast yo will burn through a blade in no time.

MetalHead 09-20-2009 07:55 AM

Re: Cutting METAL roof.
I'll second the grinder approach with the thin cutoff wheels (4")

DeWALT DW4624 6" X 1/4" X 7/8" General Purpose Metal Grinding Wheel (10 Pack) at

When you use it you want to take a 4 foot level and draw a pencil line along the underside of the panel. Chalk lines (especially red) are a pain to get off.

When cutting do so in a manner that draws the grinder away from you with the panel on its back belly up. Out in the grass is a good spot. Some take the shield off, BUT BE CAREFUL if you do this.

The drawing away and slight cutting will also save the blade. This is easy once you get the hang of it. Wear Hearing and Eye protection (Face shield is also good) as it is wicked loud and thows out dust.

But I have put up miles of metal and you can look at my project and see the metal on my roof and all of the steel joists were cut using this method.

Be Safe!!!

splatgirl 09-20-2009 06:11 PM

Re: Cutting METAL roof.
I've worked with galvalume quite a bit and have always cut it with a regular circular saw with an abrasive blade. sparks and noise, check.

MK1 09-20-2009 07:22 PM

Re: Cutting METAL roof.
I've done a lot of commercial metal work. It's OK to rough cut your metal a little long but then it should be sheared or snipped to final length. If you don't, the sawed edge will rust almost immediately. The rust slowly travels from the edge inward, or fast, if you're near salt water. All job specs state no prefinished metal shall be torched or cut abrasively. I usually cut about 1/2" long and then snip to length. Outfits that use these panels everyday have a $400.00 guillotine shear.


dougrappe 09-21-2009 10:10 AM

Re: Cutting METAL roof.
Hey Lars, I have had really good results with a portable jig-saw. If you have one maybe this is an option. Get a good blade, my favorite for cutting thin metal is a carbide tipped metal cutting blade made by Bosch. This is not the carbide grit blade, but one that actually has a strip of carbide at the leading edge with teeth ground in to it. Cuts easily and cleanly, you can use a regular thin-metal cutting blade too (this carbide blade is kind of expensive ~$15 for one,) the carbide one has outlasted many packages of the standard blades.

I used this for cutting all of the corrugated galvalume for the "temporary" enclosure for my oven. I haven't noticed any rusting at the edges yet, but I did make a point to position all of the cut edges at the top where they wouldn't sit in any standing water.

good luck,


Lars 09-21-2009 11:11 AM

Re: Cutting METAL roof.
Thank-you all for tips.

I think I will try a good metal blade in my milwaukee saws-all. And, when that fails, the old circular saw, goggles, earplugs, welding jacket, etc....Oh man...


edwin881 09-16-2012 07:25 AM

Re: Cutting METAL roof.
Go wit a nice sharp edge blade with a saw and hit it hard, this might work..

MetalHead 09-17-2012 08:45 AM

Re: Cutting METAL roof.
Use an abrasive cut off wheel in a 4 inch grinder. Mark your line with pencil and not chalk. If you MUST use a chalk line, only use blue. Red will not come off for some reason.

I have cut thousands of feet this way and still have my fingers and the cut is clean. They make a mettal cutting shear, but too expensive for a small job.

Disc I am talking about costs about 2 bucks.

You can get them at Big Box stores .... and hey you may get another tool ... a grinder :D

mrchipster 09-17-2012 12:32 PM

Re: Cutting METAL roof.
3 Attachment(s)
Since you do not have a lot of material to cut and you want to invest a minimal amount of money, Get a carbide toothed plywood blade for your skill saw, It will not be much good for anything after the job but it will cut nicely and not cause the rust issues that will happen when you cut with an abrasive disk.

Build yourself a plywood jig to allow you to crosscut the panels see drawing

A 7.25 carbide blade should cost less than $20 and will work great.

I needed to cut standing seam roof at odd angles on both ends so consistency in the cuts was critical, I built a jig similar to the one drawn to allow me to cut the odd angles consistently but square cuts are easier with a jig also.


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