The Hardibacker goes down over a layer of thinset mortar nailed with roofing nails. (Hint: get a roofing nailer to really speed this up.) The process is quite similar to laying any subfloor, but cementboard can be frustrating to cut.

It takes forever to score it with a utility knife and the blade will dull very quickly. A circular saw will churn up clouds of toxic silica dust everywhere and again, dull the blade almost immediately.

Here are two ways to cut it without loosing your temper:

1. Buy a ‘cementboard scoring tool’. (Below Left) They’re usually in the tile department next to where they sell wet saws. With this you can score and snap the Hardibacker similarly to how you cut drywall. It just takes a few more swipes to dig in before it snaps. It won’t give you a very clean break, so you might want to measure about 1/8th short to compensate for this.

2. Get an abrasive jig saw blade meant for cutting cementboard. If you can find one for this exact purpose, you can use one designed for cutting ceramic tile like I did. (Below Right) I was able to make it through my entire kitchen project before this blade wore out.

I like to score and snap any cuts that I can and use the jig saw for notches and cutting out electrical boxes, etc. This process worked well for me and I was able to stay calm in the process.

By the way, if you have to make a lot of cuts you can also buy a circular saw blade meant to cut cement board. Check the reviews on Amazon, because it sounds like some of them wear out very fast, which is not cool when you just paid $50+ for the blade.

Remember to use the respirator whenever you’re cutting this stuff, especially if you’re indoors. The manufacturer recommends only using power tools like a jigsaw outside. That’s probably good advice because the clouds of dust will attack your lungs.

Happy cutting,

Peter

www.CarpentryGuy.com