Designing Kitchens and Bathrooms - Shower Tile and Hardibacker

I'm redoing a shower that has been stripped down to the studs and the pan wet mopped. I was planning on installing 1/2 hardibacker to the studs as the base for my ceramic tile. Do I need to install a vapor/moisture barrier (such as 15lb felt) between the studs and the hardibacker?

Yes, install a moisture barrier of either 15 lb felt or 4-6 mil poly sheeting. Unless the walls were planed at the bottom to allow the thickness of the tar pan to be recessed flush with the stud faces, you should also furr out the studs first. You will notice a series of weep holes on the clamping ring to allow your mortar bed. Make sure these are not clogged with the tar. Might not be a bad idea eithre to comb a layer of thinset along the bottom to ensure the bottom edge of the cbu has a firm backing against the tar. No screws through the bottom 8" of cbu, your mud bed will wdge it in place.

Is there a bench in this shower? How was the hot mop handled for that? It could change a few steps.

Yes, install a moisture barrier of either 15 lb felt or 4-6 mil poly sheeting. Unless the walls were planed at the bottom to allow the thickness of the tar pan to be recessed flush with the stud faces, you should also furr out the studs first. You will notice a series of weep holes on the clamping ring to allow your mortar bed. Make sure these are not clogged with the tar. Might not be a bad idea eithre to comb a layer of thinset along the bottom to ensure the bottom edge of the cbu has a firm backing against the tar. No screws through the bottom 8" of cbu, your mud bed will wdge it in place.

Is there a bench in this shower? How was the hot mop handled for that? It could change a few steps.


There is no bench. Thanks for the information.

We were told a utility knife would cut hardibacker. What say the experts?

Lots of blades...score, score, (maybe score again) then snap. If it was durock then you'd have to cut the fiberglass mesh.

Might be a better way, but thats the way I did a small bathroom.

Hardibacker can be a PITA to cut, especially if you don't need a large piece.

I usually end up outside in the driveway cutting it with a skil saw with a masonry blade. VERY dusty though.

Hope you wear a mask Mark... hack hack cough cough!!

IMO a utility knife takes forever.Big boxes sell a tool designed to cut Hardibacker. I think the cutting edge is tungsten carbide. You score the board the same as with sheetrock except a degree of difficulty of X5. It works pretty good on straight lines and semi OK on large curves but not so hot for cutting holes.

I use a skil saw, too, but I find a small angle grinder with a 4" diamond blade not only cut the straight lines, but is neat for cutting notches, circles, etc. Dusty is an understatement. Windy day is nice, just be be downwind. Mask is a no brainer.

I use a skil saw, too, but I find a small angle grinder with a 4" diamond blade not only cut the straight lines, but is neat for cutting notches, circles, etc. Dusty is an understatement. Windy day is nice, just be be downwind. Mask is a no brainer.


It cuts just fine with a carbide blade. They are cheap, use it up and throw it away. Wear a dust mask.

I agree, but the diamond blades don't wear out like the carbide ones do, and you don't have to replace them as often. I've been chewing on one now for nearly a year. It does take a couple of passes to get a good clean cut, however rather than cutting with a circle saw.

Try the backerboard shears, they work great on hardi.

PacTool International :: SnapperShear dustless fiber-cement siding shears (http://www.pactool.us/snappershear/)

And how much do those babies run Johnny?

My recollection was about $225.00. Well worth it if you work with a lot of hardi. Obviously doent make sense for a diyer doing one job.