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Permabase Cement Board Shower Wall Tips for Beginners

In this tutorial, you’ll see tips for how to use Permabase cement board inside showers.

My previous tutorial gave tips for attaching cement board to shower stud walls.

Since cement board panels come in 3 ft x 5 ft sections it makes the installation much easier than you’d think.

With that said, some tips make the final steps of cement board installation less frustrating. 

And I’m going to share those with you today.

How to Cut Large Holes in Permabase Cement Board

Cutting accurate holes in Permabase cement board can be difficult.

And you want those holes accurate for the shower valve and tub spout.

The first step is to get the location of the shower valve.

For instance, in this shower, it was 13-1/4 inches from the main shower wall.

Shower Valve Location for Permabase Cement Board

And 36-5/8 inches from the cement board/drywall transition.

Shower Valve Location for Permabase

This location marks the center of the shower valve on the Permabase cement board.

Marking Shower Valve Location on Permabase Cement Board

I carefully measured the radius of the shower valve and determined it was 2-1/2 inches.

But I wanted a little wiggle room for the final cement board hole and made it 2-13/16 inches.

Shower Valve Radius for Permabase

Here’s the deal,

Cutting a perfect hole in Permabase is easy with a scribe.

I made a scribe with two cement board screws and a sturdy piece of scrap wood.

The first step was to place a screw 1 inch from the edge of the wood.

Then I positioned the second screw at 2-13/16 inches from the first screw. This was the radius of the shower valve location.

Then I drilled the first screw into the mark on the cement board that indicated the center of the shower valve.

Scribe for cutting Permabase cement board

This allowed me to turn the scribe and cut through the mesh and cement layer in the Permabase

Cutting Holes in Permabase Cement Board

At this point, the hole is halfway to completion.

I turned the cement board over and inserted the scribe in the center hole.

I used the scribe to cut through the mesh and cement on the back of the panel.

How to Scribe Cement Board for Shower Walls

Finally, I used a hammer to remove the scored circle from the Permabase.

How to Make Large Holes in Permabase Cement Board

This scribe method is cheap and effective.

How to Cut Small Holes in Permabase

Most showers have either a tub spout, shower head, or both.

So you’ll need to cut small holes in Permabase for those.

In this shower, I got the location of the tub spout by measuring the distance between the side wall and the tub deck.

And this time, I used an old hole saw to make a hole in the Permabase.

Hole Saw for Permabase Cement Board

Normally I use 1-inch hole saws for copper tub spouts.

Another option is to use 1-inch diamond hole saws.

Diamond Hole Saws for Permabase Cement Board

I typically have these on hand for the tiles.

But they work well for Permabase cement board or KERDI-BOARD.

Cutting Small Holes in Permabase Cement Board

Making these holes as accurate as possible is important.

That way the Permabase will fit tight against the shower valve.

Permabase Cement Board for Shower Valves

And the tub spout.

Permabase Cement Board Tips for Tub Spouts

I used 1-5/8 inch cement board screws to attach the Permabase cement board directly to the studs.

Screws were spaced every 10 to 12 inches along the stud height and about 1/2 inch from the edge of the panel.

Permabase Cement Board Tips for Tub Shower Walls

Most cement board manufacturers recommend a 1/8-inch gap between cement board panels or drywall.

Then I use modified thin-set to fill in the screw locations and embed alkali-resistant mesh in the corners and seams.

Permabase Cement Board

Finally, I use RedGard to waterproof the Permabase after the thin-set cures for a day.

RedGard Waterproofing

Honestly, I wish I had known these tips before I did my first shower.

So hopefully they help you out.

What’s Next

Keep in mind, Permabase cement board isn’t the only type of backer board for showers.

KERDI-BOARD is terrific, much lighter, and more versatile.

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Installing Cement Board