Cutting Cement Backer Board

I've seen installers on TV shows score it with a knife, snap it along the score mark, then cut the webbing with the knife to separate the pieces.

That works.

I try to lay it along the edge of a table where you want to snap it, hold a 6' level on top of it, and pop it quickly. The edges can be cleaned up with some 36 grit sand paper, if needed.

They have saw blades that will work, but it's a dusty mess.

this should work......no guarantee the cut will be nice and smooth

www.youtube.com/watch?v=jMEvtf8dt7w‎

Watch and learn

I'd be lying if I said haven't used a junk circular saw with a junk blade dozens of times.... Loud, fast and accurate. It's good to break out a face shield for this mess.... And hold your breath.

When I built my tile and glass shower I used a 7 " Skill Saw, some safety glasses, and a respirator.

It worked fine. I pre-drilled the backer-board screw holes and used the special screws.

Get one of those quick flippy things that has a drill bit on one side and a Phillips screw driver on the other. The drill side should have a counter sink.

Counter sink so the screw heads are flush or just below the surface of the backer-board.

The easiest way for you is to tell someone and have it cut for you.

The knife is pretty hard to cut in some board deep enough. In our projects we used:

in function of the dust produced:

1. old manual saw with handle and to apply with elbow grease.

2. multi- function tool with saw

3. jig saw low rev, not sure about dust but also the reciproke bigger brother. Old blades

4. 7 inch circle saw electrical

5. grinder- cutter disc.

Depending on the lin. feet to cut, the work situation, the dust produced, all of these work. New saw blades tend to get dull quickly because of the abrasive nature of the sheet material. It is always handy to keep some old ones for these "dirty" jobs.

You can always bill a good one. But that is dishonest.

%Stanley knife or old hand panel saw. This material can be stripped the other way, so if you need a very thin layer like i did the other day, hand panel saw it down the thickness, then scrape the foam off, comes off clean, then contact adhesive the skin down.

CNC jim

Foam? That is not what we have here. I have been talking about mesh reinforced cement 1/2" thick wall sheet to tile on. Did I miss the basics?

Oh, the solid stuff! Yes, I have used it once, but the health warnings on it put me off. I was thinking the material which has a foam centre, and a screed of mesh reinforced cement a mil or so thick on each side. Light rigid, easy to cut insulating. Marmox is one make. Tile backer board

Brilliant stuff. I thought it was odd someone would struggle, although not that odd.

look it up, see what you think.

CNC jim

I use a 4 1/2 inch angle grinder with a diamond blade. works great.

this also comes in handy while tiling , if you need to make some intricate cuts.

oilcan13

You cut it with a cement backer board saw, silly man. Otherwise just use a utility knife and a table with a good straight edge to pop it, then also cut the backing, just as others stated.

Solid stuff, not the foam. I am laying it down in a kitchen floor to put some big ol' tiles on top. I was just wondering how others do it.

thank you all.

You can score it and break just as you would dry wall.

But we use one of these.

With a carbide blade. They actually make a blade for cutting. We just use a standard carbide wood cutting blade.

Sumbuddie needs to engineer an "Idiot_Proof" blade/shaft configuration...

...Is it just MY browser's 'Zoom', or...

...does this saw run backwards , requiring a bit of "Down" pressure...?

I guess, people who have no clue how to put a saw blade right should not use electric circle saw machines (and more)

. . . . ! . . .

I ... am ...

...Danged!!!

Y O U R response led me to WONDER...

Where-in-the-WORLD would oz have snagged a photo like THAT....(?) [Blade on WRONG]

Nobody HERE would probably ever exhibit the slightest HINT of ... what's the right word to use here...(?) ..."concern" about it...?

WELL ... GUESS WHAT ...?

Go to Google , to find images-or-photos of circular saws, and GUESS what pops-up.

. . .

THAT VERY IMAGE (the one oz used) is in the "Hit_List"....

and . . .

where it LEADS YOU.

Future readers here will probably WONDER "What's the Fuss?", because chances are, the site "How Stuff Works" will FIX their Boo-Boo as soon as somebody tells them...!

And THIS IS EXACTLY THE SORT OF THING that led me to post my similarly-veined comment:

"Encooraging WWW "authors" to dumb-things-down and jumble things up ain't doing future generations ONE IOTA of good" HERE (<link).

I've seen blades used like this for cutting sheet metal, i.e. corrugated roofing, metal siding, a bit noisy, but it works well.

again I strongly recommend that you try a circular saw. please . scoring with a blade and snapping is hardly effective on concrete backer board . it is also the type of project that invites injury . Scoring will leave you with very dull knife blades and very inaccurate edges that either fall short , or need to be sawed further . a circular saw is fast so the brief rain of harmless gravel is well worth it. just marked with a Sharpie or a good pencil and go to it . Also wear hearing protection.

They make a shear especially for this purpose, that is like a sheet metal shearing cutter, that leaves a curled piece ahead of the cut. It is mated to a Milwaukee 1/2 " drill, and allows not only straight cuts, but curved ones also like for going around toilet drains , and curved tubs. Have seen tile setters do rooms with a minimum of plastic covering and mess. Just sweep or vacuum up the curled remnants. Very little dust About $380. I have also used a 3 and 4 inch angle grinder, with a diamond cement blade, but only outside and with a good mask, and no neighbors...

You say your using it on the floor? There are several products that mix like cement only thinner that leaves the floor level for tile, Im not sure how you expect to level the backer board. I have used to backer board many times, scoring with a utility knife and smack it with a four foot level. Any kind of power saw is going to leave a heck of a mess and cause you to wear some breathing protection even if outside, and will take longer to install. On floors for showers, etc I prefer to mix some cement with very little water and no gravel where it can be shaped easily for a drain, cement mixed this way dries out very hard, and can be used as a bed for tile. Your biggest problem is making it level or you will use way too much mud to level the tiles.

I've laid quite a bit of tile and I use the old utility knife, drywall t square and a lot of muscle. Make sure you hold the t-square down tight with the board. Push really hard when you score the board with the knife. Then put the board on a few cinder blocks and step on the other side of the score. If it's a thin piece, you may need to clamp two 2x4's on both sides and break it off with a pipe clamp. To clean the edges, I use one of those auto body sanders (I think they call it a speed file) with 16 grit paper. You can buy one at an auto body supply shop or Harbor Freight sells them also. Get a few sheets of sand paper and a lot of utility blades (wonderboard eats them up fast).

Another tip, I recommend putting the wonderboard on a piece of old drywall that is wider than the board you're cutting, so at the end of the cut, you blade won't hit the ground below (either damaging the blade tip or the floor).

It's not as hard as it may sound, but it's not as easy as cutting drywall.

I hope this helps.

Thank you all. I will see what works this week end.

Thank you again.