Cutting Durock [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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John D
09-16-2002, 04:56 PM
I have two oldtimer (Dad and Uncle) tilesetters ready to do the ceramics on the bathroom floor and shower stall and "I" have decided to use Durock as the subfloor over new plywood for the floor and Durock in the shower. This Durock use is much to thier dismay. Never used it etc. etc.
How is it cut?
John D

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09-16-2002, 05:03 PM
Hi John-

Never cut Durock! Only use full sheets :D - Just kidding.

I've used two methods, first and most common is to use a carbide tipped scoring tool to score the sheet and break it kind of like sheetrock. This generally works well, but can leave a ragged edge that you may need to smooth using a wrasp.

Second, if you are outside or well ventilated you can use a circular saw with a carbide tipped blade. I was amazed at how well my Skilsaw cut the stuff over and over. The cut edge is nice and clean. The only drawback - DUST, lots of it.

Good luck,


Bud Cline
09-16-2002, 05:15 PM
I use a 4-1/2" diamond blade in a circular saw. Lotsand lots of dust. Protect your lungs my friend.

John D
09-16-2002, 05:23 PM
Wow, that was fast. Buried I have to tell ya.I almost lost my supper when you first said "never cut Durock".
I will cut it outside with my skillsaw, I have both blades and a Comfo 2 resperator.
Thanks a million guys.
PS Don't tell my Dad I called him an "oldtimer". Those guys have been tiling for over 50 years and have forgotten more than I will ever learn. Thanks again.

John D
09-16-2002, 05:25 PM
Sorry to bug you again all. Bud did you mean 7.5 inch blade?

John Bridge
09-16-2002, 05:33 PM
Hi John,

The larger blade will work.

These oldtimers must be mud men. Why not let them do it their way? ;)

[Edited by John Bridge on 09-16-2002 at 07:58 PM]

09-16-2002, 05:38 PM
A carbide tipped $4 blade from the big box. Don't expect it to last more than about 20 sheets. Gets hot and dusty, but it is cheap. Throw the blade away.

A masonry blade (cut off blade). Lasts forever, but not quite as nice of a cut as a diamond tipped blade. A $10 investment. My current favorite.

A diamond blade. $20 to $100. When the masonry blade wears out this will go in the tool box. Most are 4", or 4 and 1/2", or 7" or 8". I have not seen the 7 and 1/2" which would fit into a standard skill saw set up. No harm using something smaller, as you are only cutting 1/2", right?

Wear a good mask, not a stupid paper one. Cut outside and pray for wind.

John D
09-16-2002, 06:07 PM

Yes they are mud men. I remember nailing down rolls upon roll of chicken screen when I was a kid. Mixing wheelbarrows of mortar. Why are they doing the tiling one may ask? They wouldn't let us touch a tile when we were kids for fear we would screw one up. So I will be mixing again but no way am I going to lay mesh down. I had to rip the floor out to the joists and change more than a few. This job is at the cottage that's over 60 years old. I want that floor as solid as possible as I am in Canada and from what I saw in the crawl space there has been movement over the years due to the frost line, thus the cracked joists.
I was advised to lay down 1/2 plywood and then 1/2" Durock.
I was going to lay down 5/8 and 1/2 Durock but was told it was overkill. With the 1" subfloor and the new tile there is no transition from room rto room. I have braced the new 2x8's every 48".

John Bridge
09-16-2002, 08:42 PM

I don't know who told you that, but half-inch plywood doesn't get it here and not in Canada either. For corraboration of that you can check with our amigos in Ontario. Post it to Harry's board.

09-16-2002, 11:48 PM
Hey John D-

I've been a bit scared :eek: around here at times, but really, this is a great place! Lots of great people to help. Have fun!


Bud Cline
09-18-2002, 06:22 PM
John D,

I've been using this same 4-1/2" blade in this same little Skil Saw for about six years now. All I use it for is cement board and the thing is now beginning to show some signs of being used. I blow out the motor frequently and have never had a problem. The motor does growl a little at me now when it idles down but I've had my share of use from the saw and the diamond blade.

Jerry The Tile Guy
09-18-2002, 08:40 PM
I can only dream of the mess when you use your saws on that stuff. I have cut Hardi board a few times when the wind was blowing hard and there was someplace for the dust to blow to. That is where Bud has it made the wind blowes all the time.
I cut all of my Durock and Wonderboard with a small wooden handled laminate cutter. I use a circle cutter to score a line I trace with the tool for holes.

09-19-2002, 04:18 AM
Something is wrong with my eyes i think.I saw Mudmen available but was advised to use plywood and Durock.Who advised you?if you have movement in your floor,the plywood is certainly a plus,but CBU over Mud???????
I am in Northern Minnesota,In your situation Mud is the way i would go.You were going to go 5/8,Plus 1/2"durock
Why not go 1/2" and 3/4"mudbed???
Its up to you ,but whoever told you CBU was better than a mudfloated floor has'nt a clue.Musta been from H*** D****
They'll prob try to sell you a left handed tile cutter too :D

Bud Cline
09-19-2002, 07:27 PM

You know your right about the wind. There have been occaisions when I have used a fan to continually clear the work area of all the dust. We always cut outside of course and a few days a year the wind doesn't blow here. I have to use a "turbo" to make up the difference though.

John D
09-26-2002, 08:58 PM
Just to let you guys know, no Durock on the floor.
Went with 3/4 inch plywood, mesh and mud. Ready for the tile now. Man the floor is solid.
Thanks again.

09-26-2002, 09:23 PM
:) :) :)

John D
09-28-2002, 03:44 PM
Cut the Durock. NO MESS. I got to thinking about the dust that was going to fly, no wind as well.
I used my little Craftman circular saw (no problem), when I started cutting my wife stood behind me with my "leaf blower" and aimed the thing at the saw as I cut. The blower blew all the dust away, fast. And it felt kinda nice too!