What is the best blade for this, in a power saw??

Carbide, but you don't say for what tool..

now specified in OP

Which type of power saw?

I am cutting for metal roofing..
What 'type of saw' would you use?????

On a skil saw some just place blade on backwards and use it that way.

It’s been my experience that circular saws, sawzalls, or side grinders suck for cutting metal roofing. Metal chips or sparks will eat you up.

Get a hand shear, you’ll be glad you did. That’s what they are designed for and it works great.
https://www.homedepot.com/p/Genesis...ectric-Power-Metal-Shear-GES40/300536821

If it doesn't have be precision use a Quickie saw with a metal blade we used them all the time to cut rebar, if precision matters get a blade for a table saw osr skill saw that will cut metal. Ive seen some use a finish wood blade turned around backwards on a skill saw

I used a grinder with a cutting wheel

Will those cut through the raised ribs?

We always used a dull saw blade turned around backward, and use a good pair of goggles.

To be ideal I would use a plasma arc cutter to be quicker and look better.

They sure will. I use them on r-panel roofing when skinning doors for dumpster enclosures.
I think harbor freight sells them for about 20 or 30 dollars.
I have cut panels every way you can think of. There is no comparison imo.

https://www.amazon.com/gp/product/B07PZ8RCNL/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1

It takes some finesse to work with big corrugations but these work well for flat stuff. Used a mix of tin snips and these on our big barn project.

Plasma would be the last thing I would use on metal roofing. When shears do the job, are affordable, designed for the work. That said a razor cutting wheel on a 4 1/2" grinder , works wonders when cutting more than one the same length. Stack three together and geter done!

I have a hand held electric shear from Harbor Frt. It works great of flat metal but it can't handle the bends in corrugated. The backwards blade in a circular saw is much less frustrating although not pretty.

Here’s a video of a guy cutting crossways through the ribs on an r-panel. Go to 8:45 mark.
I’ve found that it’s easier to go through the ribs if I pull out of the cut and use the shear closer to the tip end rather than cutting at the back of the throat.

YMMV

👆

I'll add a good set of ear muffs too.

This method is annoyingly LOUD.

HUH?





lol

THIS .....

https://www.homedepot.com/p/DEWALT-7-1-4-in-Iron-Steel-Saw-Blade-DW3330/202579864

I have cut a lot of metal roofing with the circular saw. I use a standard metal cutting blade.

I got a blade from my steel dealer to put it in a Skil saw got a bunch of teeth on it you cut a stack of that metal at one time .....you better have some glasses and long sleeve shirt or it's going to hurt can't ....remember what the name of the blade is it's going to be at a place that makes gutter ..roofing metal and stamps it out that's who would have it

I’ve used an angle grinder w abrasive wheel a lot. There is a metal wheel with carbide or diamond edge that works and lasts longer.

When cutting length wise I score it a few times with utility knife and then snap it over. If it’s scored right it’ll snap off. Cutting over the humps I have had best results with my angle grinder with a 1/16” abrasive wheel.

>>——>

Added; ear muffs for sure.

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If you're not doing much cutting, you can get by with the old methods (grinders with cut-off wheels, backwards saw blades, shears, re-cip saw).
If you have a lot to cut, then I'd use one of the new metal cutting blades for your circular saw.
Bosch invented them and now there are a bunch of knock-offs. They're expensive, $30 - $50 but they last and do an awesome job. I have them re-sharpened at a saw shop.
From a distance they look like a regular Skil Saw blade, but the teeth are a different design.
They will cut through 1/4" wall steel tube almost like it was wood.
Let your saw ride on plywood (make up a jig) so you don't scratch up your paint and if possible, PUT THE CUT END UP. This puts your cut end out of the weather.
The cutting will be LOUD. Wear your ear (and eye) pro.

The blades look like this. Take a look at the teeth.

Are you kidding me? Cutting metal roofing by scoring with a utility knife? I never heard of that, it seems like it wouldn't work.