How to Build a Stunning Tiled Skoolie Shower with a Mortar Shower Pan

Ted Tibbetts // March 6 // 0 Comments
Skoolie Shower

After spending a summer day in the sun, slathered in sunscreen and wearing old river gear…well it would be a good idea to have a skoolie shower!

As with many aspects of skoolie conversion, (or with house building for that matter) a myriad of choices flood us…even more than a potential drain leak!

Option #1:  A Conventional Unit

For many, a conventional fiberglass unit is the easiest.  You can pick up a 32×32” unit for around $270, drop it in and be done.  

Although you may have to cut the top off if you don’t have a roof raise!

This wasn’t an option for us as we are working our bathroom around the wheel wells.  A conventional shower stall simply won’t fit.

Option #2: Bathtub Tank

Many people choose to repurpose other kinds of tanks as a bathtub or partial shower unit.  For example, they’ll use a livestock watering tub or the like.  

Like the conventional shower unit, however, for us, it wouldn’t fit.

AND…there’s still the issue of waterproofing the wall.

Option #3:  Metal Roofing Material

I considered securing metal roofing the wall as a shower stall.  The rubber gasketed screw would keep the wall watertight.

But metal roofing isn’t overly cheap these days and the used stuff I could find…well…didn’t look so hot.  And I wasn’t sure how I liked the look to begin with!


As a carpenter, I really like the look of natural wood.  AND I really like working with it.  I had a cedar shower in the house as a kid and really liked it.  It didn’t leak and looked “homey.”

Cedar it was, I figured!

Then I checked today’s cedar prices…$14 a board!!  I know lumber has gone up, but that was going to be a $280 shower…just in lumber, not including everything else.

Tile and Mortar Pan

I had already decided on a mortar shower pan.  It seemed like the most cost effective way to customize the shape of a shower pan.  Mortar was $12.  The liner was $30.  The drain was $15.  So for under $50 I could build a custom pan FAR less than the $200 I’d pay for a pre-fab one!

Then came the issue of tile.

I would have really liked to have done a river themed mosaic.  But I have NO visual artistic talent.  




It would have looked like dog vomit.

So a mosaic was out.

I would have liked the river rock pebble approach.  However, it’s February and there is two feet of snow on the ground.  Can’t really find any natural material these days to work with.  

And buying river rock pebble tile would cost $10 a foot.  (Another material choice that would have approached $300!)


We have a repurposed building supplies store about 45 minutes away.  They have OODLES of tile laying around from leftover jobs.  OODLES.  

(An “oodle” in tile terms is 324,549 square feet.  Plus or minus).

I was just about ready to jump in my truck and drive through a snowstorm to pick out tile when my neighbor called to say he had about 30 feet of leftover subway tile and ¾ a gallon of mastic left over from a job.  It was mine if I wanted it.

No brainer.  

Couldn’t beat the price and I didn’t have to drive an hour and a half in the snow to get it.

Subway tile it was.


I wasn’t positive which way I’d orient the shower when I framed the wall separating the kitchen from the bathroom, so I had used 2×2’s like I had for the rest of the bus.  

When I decided that I would mount the mixing valve and shower head on that wall, however, I needed to add another 2×2 wall to it to make it thick enough to fit the mixing valve.  (So remember to frame out plumbing walls thick enough to hold plumbing components!) 

A also added a 2 ½ foot wall opposite of that wall to separate the composting toilet area from the shower.

To support the mortar pan, I used pocket holes to secure 2 x 6’s in between the studs of the wall framing.  


I ran pex hot and cold water lines with shutoff valves into the wall, then installed the mixing valve.  From the mixing valve I ran a pex line up to the “drop eared elbow” at which I will connect the shower head in the finish plumbing phase.

Mortar Pan

As I said before, I chose a mortar pan because of the low cost and ability to customize the shape..  

I do have some concerns about it cracking, so we’ll see how it goes!

I’m less concerned about leaking, however.  I feel pretty confident in the security of the liner, so…like I said…we’ll see!  


I used ¾ inch Advantech OSB for my subfloor.  Now, of course you’ll see all kinds of rants and warnings on social media sites about the evils of OSB (Oriented Strand Board) and particle board.  (Often jokingly referred to as “fallaparticle board.”)

People often claim that a plywood is much more resistant to moisture.

They are only partly right.

Advantech is not your run of the mill OSB.  It’s engineered to be a subfloor material.  It’s waxes and resins hold up to water extremely well.  And the tongue and groove “locking” system will keep edges from curling.  

When I built my last house, I decked over the floor joists in December with Adventech.  In May I framed the house.  After a hellacious winter with FEET of snow, my floor is still flat and true.

It’s good stuff.

So I am confident in my subfloor!


The curb must, obviously, function as a dam redirecting water away from the rest of the bus, down the drain and into the gray water tank.  I wanted it high enough to accomplish this task with becoming a menacing trip hazard.  

I started with a piece of rough cut hemlock…truly 2 inches by 4 inches.  I used a Kreg Jig to drill pocket holes on the 4 inch face, then, standing it on edge, I screwed it into the floor.

I cut another piece square off the pan near the wheel well.  I later decided that 4 inches high wasn’t enough.  (I suppose in the event of some drain blockage I’ll want to have a bit more flood protection)  So I added another inch and half to the top.


I had previously stubbed a drain pipe up through the floor, but still needed to install the drain.  Of course I had plumbed my drains with 1 ½ pvc pipe, and the Oatey shower drain was 2 inches.

I should add that 1 ½ inches is pretty small for a drain.  However, my kitchen sink drops straight down through a Hepvo valve and directly into the gray water tank.  The shower drain drops through the floor, takes a left, and ties into the sink drain four feet away from the tank.  

The short run seemed to justify a narrow pipe.

Anyway, I had to squirm through the snow under the bus to get to the drain.  I cut the pipe off, added a 2 inch to 1 ½” reducer, and reconnected the drain pipe.

I used some duct tape to cover the opening and keep mortar bits from dropping into the drain system.

With the drain base now in place, I could begin working on the mortar pan.

First Layer of Mortar

Shower pans are composed of several layers.  The first mortar layer provides a slope.  

The liner goes on top of this first layer.  Without a slope layer under the liner, any water that DID find its way to the liner would pool in corners and not toward the drain.

A second layer of mortar goes on top of the liner, providing both a slope to the drain, and a foundation for the finish layer of tile and grout.

In order to prevent mortar moisture from wicking into the floor, mortar pan experts recommend putting down some tar paper or flooring paper on the plywood before the mortar base.

Without any tar paper laying around, (I didn’t want to buy an entire roll for six square feet)  I used a piece of plastic I had leftover from masking when I spray foamed the ceiling.

I laid that into place and cut a piece of metal lath to fit the footprint (and with a hole cut out for the drain).  The metal lathe helps hold the dried mortar together and reduce cracking.

Metal Lath to Support the Mortar Bed

Also, shower pans should slope toward the drain ¼ inch per foot.  Since my shower pan is only 3 x 2, I didn’t need a mountainous slope!  I decided that half an inch would work on the 3 short sides with 3/4 “ on the long side.

I cut a couple pieces of scrap wood to that width, then set it on the floor and traced a line along the framing of the perimeter of the pan to mark the outside level of the mortar.

Mortar Choices

I had several choices for mortar.  Mortar often comes in types N, O, S, or M, dedicated by the different proportions of portland cement, lime, and sand. 

The most common types are N and S.  Type N mortar is considered for “normal” use and has a compressive strength of 650 pounds per square inch.

Type S mortar is stronger.  Builders use it for underground applications like foundations and patios.  It has a compressive strength of 1800-3000 pounds per square inch.

While I’m not that heavy, I opted for the strength (and adhesion to resist cracking)  of the Quikrete Type S mortar.  I am hoping that increased bonding to the lath will prevent cracking.

My first attempt to mix mortar didn’t go well.  I thought I was being smart using my Milwaukee drill and a paint stirrer attachment in a five gallon bucket.  Seemed to go well at first; but when I dumped it out I had a bunch of dry mortar mix at the bottom.  I remedied this approach in later batches!

At any rate, it’s important to ADD WATER GRADUALLY and mix.  Mortar can quickly turn into soup with too much water.  The mix should just be wet enough to stick together like a snowball.  If it’s too wet, it won’t hold the shape of the slope while drying.

Packing Down the Mortar

Dumping the bucket of mortar onto the lath, I spread it around, fairly loosely, approximating the slope so that the mortar reached up to the line on the outside and worked its way down to the level of the floor at the drain mouth.

Using a one-foot length of a 2×4 and a hammer, I packed the mortar into place trying to eliminate any air pockets and really compress the mortar.  

Once I got the desired shape packed down, I used a wooden float to smooth the surface.

Smoothing the Mortar Shower Pan with a Wooden Float

I cranked up the diesel heater and let it sit 24 hours before working on the liner.


I draped the liner over the dried mortar bed.  Well…wrestled it into place would be a more accurate description! 

Oatey Shower Pan Liner

I had brought it inside to stay warm and hopefully more workable, but it still must’ve been cool because I found it awkward to work with!

Part of the challenge was poor design on my part.  The awkward shape of the shower pan made it impossible to make the liner fit without cutting and gluing a patch into one section.

I did have an outside corner patch and some Oatey glue.  As with most contact cement, I applied glue to both surfaces, let it dry for five minutes.  (One good trick I always use when gluing raft patches is to touch it with my knuckle.  If it’s tacky (sticky) but not wet, then it’s ready.

Sticking the two pieces together I set weight on top of the pieces to hold them in place while the glue set.

Since it was an awkward corner, I let the glue set overnight.  First thing in the morning I poured 5 gallons of water in the liner and let it sit for a couple of hours to check for leaks.  (The directions say 4 hours, but since I only had one spot to check I figured it would be pretty obvious.

I vacuumed out the water and lifted the liner:  no leaks!

Setting the Drain Height

I screwed in the barrel to the drain so that the top of the drain sat about an inch and a half above the liner.  That way, I had enough mortar for strength but not make the shower pan so high that I would whack my head on the ceiling.

I put a couple of handfuls of pea stone around the drain to keep mortar from getting in and blocking the weep holes of the drain base.

2nd Layer of Mortar

I mixed up a second batch of mortar…the old fashioned way this time:  with a masonry hoe! Masonry hoes have holes in them which allow the mortar to swish through and mix smoothly.

Using a Masonry Hoe to Mix Mortar

I hired a mason to build the Russian fireplace that we have in our house.  He taught me to mix mortar by “chopping” the hoe into the mix, gradually adding water.  Once the mortar has become moist (not wet!), start pushing and pulling the hoe through the mixture forcing the mortar through the holes of the hoe.

I shoveled a bucketful, carried it into the bus, and spread a 1 inch layer on top of the showerpan liner.

Next, I cut another layer of metal lath, and pressed it into the mortar, then added another inch of mortar on top of the lathe.

Again, I compacted it with a hammer and a 2 x 4, matching the slope established before with my first layer.

After packing it all down and finalizing the shape, I used a float once again to smooth the finish.


I waited for the mortar to dry overnight.  I wanted to give it some extra time to cure, though, so I used this time to finish waterproofing the shower enclosure.

Installing Hardibacker

I used hardibacker cement board “with hydrodefense technology” to close in my walls.  The waterproof membrane on the outside makes it unnecessary to use Redguard or similar product to waterproof the material.

Using a Masonry Blade to Cut Hardibacker

Many people use either an exacto knife or somethign similar to score the cement board, then snap it. That seems to take WAY to much effort and time for me.

Instead, I put a masonry blade on my skill saw and carved up that cementboard like a Thanksgiving turkey!

To cut the curved part that fits up against the ceiling I used my Bosch jig saw. IT completely trashed the blade after the one cut. However, it was worth one blade for the ease and smooth quality of the cut.

A word of caution, however. Cement-board contains silicates which are really bad for your lungs. So do this OUTSIDE and wear a good quality respirator!

I installed the hardibacker using 1 1/2 inch cement-board screws. These are a bit long for 1/2 inch cement-board but I had them on hand and I figured the extra holding power would be beneficial.

Installing Hardibacjer

Taping Seams

The instructions do say that “• When complete waterproofing is required, seal all joints, edges and fastener penetrations with a liquid waterproofing membrane.”  I interpreted this to mean if the material would be fully submerged.  Since I won’t be using the skoolie shower as a hot tub, I skipped this step.

Instead, I taped the seams with thinset mortar and nylon tape.  I spread a layer of thinset on the seam, pressed the mesh into the mortar, then troweled another thin layer onto the mesh.

Once again, I let everything dry overnight.


So, time to get into the “make pretty” phase of the operation.  With a stack of subway tile at the ready I spread Acryl Pro with a v-toothed trowel and started sticking tile to the wall. 

Why Acryl Pro, you ask? Good question. Because my neighbor who has been a contractor for 40 years uses it. Works for me.

I staggered the joints.  

Skoolie Shower starting to Take Shape!

When I got to the end of a row I used a tile saw to cut the tiles.

One thing that I should have done a better job with was to better anticipate the end tile.  Sometimes I would use an off-cut to start the next row, and when I got to the end, I was left with a one inch space for a little piece of tile.  This doesn’t look great.  I should have trimmed the cut-off piece a bit more so I was left with a larger piece at the end.

This is why I am not a professional tiler.  But I’ll be better next time.

Tile with Spacers

River Pebble Shower Pan Floor

I had several one-foot squares of river pebble backed by nylon mesh. I laid them out on the shower pan trying to get the spacing right. Since once side of the pan only extended about 18 inches, I used an exacto knife to cut the mesh and separate some of the rocks.

Similarly, I cut out a hole in the middle to allow for the drain.

River Pebble for the Skoolie Shower

In some spots, I had to fill in gaps with loose pebbles that I had ripped off from the mesh. (This isn’t ideal because these loose rocks don’t tend to adhere as well, so I had to be extra generous with mastic with these ones!)

After laying it all out and getting the “fit,” I pulled up the mesh squares and loose rocks one by one, applied mastic and pressed them back into place.


You should let the mastic cure for at least 24 hours before grouting.  While the seams may seem dry and hard in less time, the mastic in behind the tile may still be soft.  Since the bus will be rambling over bumpy roads I wanted extra strong curing, so I waited 48 hours.

Sanded vs, Sanded vs Silicone Grout

Grout fills in the gaps between tiles, provides a bit more structural support, and helps seal out moisture.

Sanded grout has…well, sand particles.  The sand provides a bit more ruggedness and support to grout.  However, because it’s a bit “stiffer,” it’s harder to work into smaller spaces.  Also, sand might scratch softer or shiny tile.

The more delicate non-sanded grouts are easier to work into small gaps and are less likely to scratch tile.  However, they don’t provide as much support.

People have suggested that I use a silicone based grout which could provide a better water-tight seal.  In addition, the flexible nature of the silicone would allow it to flex on a moving bus and resist cracking.

However, I wasn’t confident in my ability to not make a royal mess flinging silicone around.  And, I believe silicone is more susceptible to mold and mildew.

Apply Grout

I attempted to capture the best of all worlds by using Prism “Ultimate Performance Grout.”  According to its specs, Its “unique blend of lightweight recycled glass and fine aggregate sand allows for a smooth consistency that is easy to spread and clean.”  Thus, I hope to get the rugged performance of a sanded grout with the ease of spreading of a non-sanded variety.

I used a grout float to smear the Prism into the joints. Applying at a 45 degree angle worked the best.

After 30 minutes of work I stopped to wipe the grout from the tiles before it had hardened too much.

After three hours, I returned and wiped the haze from the tiles with a terrycloth rag.

Sealing Grout

By not choosing a completely waterproof grout, I still needed to seal the Prism to keep it waterproof  and stainproof.

Finish Plumbing

After allowing the grout sealer to dry, I completed the finish plumbing.  After wrapping teflon tape around the threads of both ends of the shower head, I screwed the shower head on and screwed the other end onto the dropear elbow.

I pushed the barrel into the shower hand mounting plate and wrestled with it for 10 minutes trying to get the screws lined up with the holes in the mixing valve.  Finally I found success and tightened up the mounting plate screws.

Finally, I pushed the handle onto the mixing valve and tightened the set screw underneath with an allen wrench.

Since temps are averaging in the teens at night, I will wait until spring before filling the freshwater tank and trying it out.

Besides, I still have to build the doors…but that’s another post!


I will enjoy the skoolie shower, I’m sure.  Whether it’s blowing the stink off from wearing wet plypro or just warming up after a chilly paddle, having the convenience of a shower on board raised the quality of life.

Next up, building barn doors for the bathroom!

As always, thanks for joining along.


Check out this cool pull out couch and leaf table here!

About the Author Ted Tibbetts

Ted, a teacher, raft guide and carpenter, has been teaching high school English for over 20 years. A Milken Award winner and a Maine Teacher of the Year State Finalist, Ted loves working on his Skoolie, "Snug," and traveling around to splash in rivers.

Enjoyed this article?

Find more great content here: