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drewdin 01-28-2013 07:56 AM

Easiest way to cut HardieBacker 500 Cement Board
I have been putting in a bunch of HardieBacker 500 the last few days, that stuff is like steel. It states in the instructions that you scour it with a knife and bend to break it.

I'm not sure if anyone has tried this but it does not work, i tried scouring both sides and it didnt help much. The only thing that worked was using a sawzall and a metal cutting blade, the only issue with that is that I went through five blades on three sheets along with the instructions telling me not to because ti creates harmful silica dust.

There has to be an easier way, does anyone know of one? Thanks

nealtw 01-28-2013 08:31 AM

You can get a blade for the circular saw. There are shears that you can rent.

drewdin 01-28-2013 10:10 AM

is there a specific blade or shears you can recommend?

nealtw 01-28-2013 11:02 AM

The blade is a diamond blade that says cement board on it. A regular concrete diamond blade will work. Get a dust mask!!!
Havn't used a shear, only seen others use them, messy cut would want to be hiddin behind trim

inspectorD 01-28-2013 11:33 AM

I always just use a utility razor knife and it cuts fine. Even when it wears down just apply more pressure. Or you can use the carbide tipped knife they sell, it more or less just scores the sheet.
A skillsaw and blade is a real mess maker...beyond dust! I have also used a jigsaw with a carbide blade to cut the circles, or arches in doorways.

Fireguy5674 01-28-2013 12:43 PM

The carbid tipped scoring tools they sell work pretty well. With two or three passes they will allow the cement board to snap pretty evenly. Since you are supposed to tape and mud your joints before applying tile any edge variations will be filled giving you a solid base for your tile. If you are making ANY dust wear a mask. You will be happy you did. It may take a number of years but that dust will come back to haunt you. They make a saw specically designed to cut cement/hardie board. It has a dust collector built into it. You might be able to rent one but they are kind of pricey for a single project.

Jaz 01-29-2013 09:57 PM


Many people have trouble cutting Hardie because they use the common sense technique to cut it. They try to cut it like drywall. Wrong! Re-read the directions.

You need to score it several times with the carbide scoring tool, then snap up, not down.

Alternatively you can cut it with a 4" side grinder equipped with a basic diamond blade, but lots of dust. Do it inside the garage near the door with a fan blowing behind you to minimize the dust. Wood pallet on the floor, board on pallet, just lightly score then snap. Still wear a proper mask.

Or if you do this often get a pair of the special shears.

Doing a floor? Why 1/2"?


drewdin 01-30-2013 08:09 AM

I have a half bath and the floor is exactly 1/2" less than the adjacent wood subfloor. I was using the 1/2" hardie to build up the bathroom floor to the same level as the wood subfloor. That way when the wood goes in it will be the same height as the tile, or pretty close.

Do you have any other recommendations? Thanks

Jaz 01-30-2013 03:10 PM


Do you have any other recommendations?
Yes, don't eat yellow snow!

If you have any other questions, you know where to ask.


drewdin 01-31-2013 11:12 AM

haha, that's what I saw when people ask for tips!

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