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How to Pour a Shower Pan

How to Pour a Shower Pan

by Ethan Hagan (email Ethan) | | September 5, 2012 | 19 Comments »

Regular readers know that I’ve been hanging out with general contractor and carpenter Joe Bianco. In preparation for moving, Mr. and Mrs. Homeowner have tasked Joe with remodeling three full bathrooms, and he has brought in Jim and Rich from Diamond Tile to pour the shower pans and lay the tile. Jim and Rich have been laying tile for over 20 years, and I’m pleased to share how they poured the shower pans. Read on to learn how they waterproofed the shower, what materials they used, how they sloped the pan for proper drainage, and created a shower pan that’s ready for tile.

Prep

Before Jim and Rich got started, Joe and the plumber have made some important preparations. You can see a curb has been installed by stacking three 2×4′s and blocking has been added between the wall framing. Also, the subfloor has been brought up to the necessary level for the drain. The guys used concrete board because it was handy and the right thickness. However, the subfloor is usually plywood.

The plumber installed a polyurethane waterproof sheeting.

Instead of cutting the sheeting and compromising the waterproof barrier, the plumber overlapped the membrane in the corners (like hospital corners).

He used roofing nails to secure the sheeting because they have broad, flat heads. All the nails were placed at least 4″ up from the subfloor in accordance with local code.

Next, the guys installed Durock concrete board on the walls. Again, you can see the nails are at least 4″ up the wall.

After the sheeting was in place, the plumber finished with the drain flange and drain.

Here’s a look at the second bathroom after the Durock was hung and the drain completed.

Pro-Tip: Sometimes you’ll see the floor pre-sloped before the base is poured. Jim and Rich will do that when the floor is way out of level or when the drain is significantly higher than the subfloor. On these bathrooms it was not necessary.

Step 1: Clean

Before getting started, the Jim used a foxtail brush to clean away debris.

Step 2: Cover Drain

Next, Jim covered the drain with tape to prevent it from clogging.

Step 3: Mix Mud

For the shower pan, the guys used Mapei 4 to 1 Mud Bed Mix. You won’t find this at your local DIY center. Instead you’ll have to go to a local tile supplier, and each bag costs about $15.

Pro-Tip: A cheaper alternative to Mud Mix is all-purpose sand and Portland cement. Jim and Rich prefer Mud Mix because it saves time.

Pro-Tip: The average sized shower base requires 3 – 4 bags of Mud Mix.

Using a mixing paddle to mix the mud, Jim added water until he achieved the right consistency, and he targeted a “dry mix” that is just wet enough to clump together when compressed. A dry mix enables the guys to work the mud and set the necessary slope without concern that it’ll move, and it will dry just as hard.

Step 4: Pour / Spread Mud

Jim poured three buckets of mud into the shower and spread it out with a straight trowel.

Pro-Tip: Jim and Rich don’t use a wire mesh reinforcement for the shower pan because it’s not necessary, and if you’re not careful when packing and spreading the mud, you can puncture the waterproof membrane.

Step 5: Pack Edges and Corners

Since the Durock isn’t nailed at the very bottom, it can shift a slightly. To eliminate any movement, Jim packed some mud tight against the perimeter and into the corners.

Step 6: Set Mud Around Drain

Next, Jim began setting the mud around the drain, and he used a floor tile to find the appropriate height. After the tile is installed, it should be flush with the top of the drain. That means the base should allow room for the tile height plus a little extra for thinset.

Pro-Tip: The mud around the drain should be at least 1″ thick to provide a strong base.

Step 7: Set Slope

Using a 2′ level and the drain as a reference point, Jim sets the slope for the shower pan, and it should be 1/4″ to 1/2″ per foot.

After Jim determined the right slope between this corner and the drain, this corner became the new point of reference for the remaining perimeter.

Step 8: Level Perimeter

Working out of that corner, Jim leveled the rest of the perimeter, packing the mud firm. Jim also looked for gaps under the level and filled them accordingly.

Step 9: Screed and Trowel

After the drain was set and the perimeter was at the necessary slope, Jim began filling the remaining area. He used the level as a screed and the trowel to finish the mud.

Step 10: Check for Low Spots

Jim went back and carefully looked for low spots with his level. He said you can usually feel them as you work the trowel across the mud.

Pro-Tip: Jim says that failing to maintain a consistent slope and fill low areas is the most common mistake when pouring a shower pan.

Step 11: Verify Slope and Drain Height

After Jim finished filling and screeding, he went back to verify the slope of the shower base and to double-check the height around the drain.

Pro-Tip: The drain flange is threaded and the drain height can be adjusted. Just be sure to preserve the necessary slope.

Finished

Jim and Rich did two pans in this fashion, and they look great. The guys will let this set overnight before starting to lay tile.

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19 Responses to How to Pour a Shower Pan

  • jb @BuildingMoxie responds...
    September 5th, 2012 9:16 am

    Great work by Joe and his crew… a work of art. props to you too Ethan. thanks for sharing.

    [Reply]

    Ethan Reply:

    Thx JB. I always appreciate the comments (not to mention the social media sharing)!

    [Reply]

  • jeff_williams responds...
    September 5th, 2012 9:35 am

    Rubber cement used to secure those preformed pieces over the curb? Also is the seat sloped and did they use membrane there (maybe paintable membrane before tile)?

    [Reply]

    Ethan Reply:

    I gotta double check but it looks like some sort of adhesive for the curb corners (from the pic), and I know it’s secure. I’ll find out what they used. I’ll also verify the slope on the seat, but I’d be surprised if they missed that. They covered the seat with the same membrane too.

    [Reply]

  • trebor responds...
    September 5th, 2012 10:36 am

    What kind of time frame does the Mud Mix give someone to work with before it starts drying? And how long to completely set?

    Looks good though! I’m surprised at how smooth it turned out after all that by hand

    [Reply]

    Ethan Reply:

    The Mud Mix gives you plenty of work time, and Jim and Rich let it set overnight before tiling.

    [Reply]

  • Reuben responds...
    September 5th, 2012 11:08 am

    This looks really great. You can tell this guy really takes pride in his work. Craftsmen are hard to find these days, but it sounds like you may have found a couple.

    Maybe you’ll talk more about this when you post about laying the tile, but I’m curious about whether they tried to create flat planes around the drain, or if the whole thing is continuously curved. I’ve seen some showers where they try to make four grade breaks extending from the drain typically out to each of the four shower corners (maybe five in this case with the seat). The area between these grade breaks is a flat plane. I’d imagine if the whole thing is curved it would be more difficult to tile, although maybe the curve is so subtle that it won’t matter?

    [Reply]

    Ethan Reply:

    Hey Reuben,

    It’s a straight shot (flat) between the perimeter and the drain at any point, and that makes sense because they used a level to screed it. The guys didn’t section the pan off into separate parts (or grade breaks as you put it). They just extended that same slope out from the drain in all directions. Does that make sense?

    [Reply]

  • MissFixIt responds...
    September 5th, 2012 3:22 pm

    Amazing job and explanation. It looks flawless in that last picture thats the kinda guy you want working on your bathroom reno.

    [Reply]

  • Joe responds...
    September 5th, 2012 5:02 pm

    sooo. how does the membrane tie into the drain to get rid of any water that might have made it through?

    [Reply]

    Ethan Reply:

    Working from the pictures I’ve taken….. The drain assembly is composed of a couple different pieces. The first piece connects to the PVC drain and sits flush with the top of the concrete board. The next piece is attached with four bolts and the membrane is sandwiched in between the two. Lastly, the drain is screwed into the second piece and that sits flush with the tile.

    [Reply]

  • poiboybf responds...
    September 5th, 2012 5:15 pm

    beautiful work. Can’t wait to see how it turns out!

    [Reply]

  • Icarus responds...
    September 6th, 2012 11:42 pm

    Almost makes me want to tackle this on anew house…ALMOST

    [Reply]

  • Build Your Own Shed Ramp responds...
    September 25th, 2012 4:03 pm

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  • Jay responds...
    November 18th, 2012 4:03 pm

    I don’t to want be negative, but I see that they screwed the backerboard on top of the the curb. This might cause leaking into the membrane and into the wood structure, wouldn’t it?
    One tutorial I saw, advised the curb to be cemented with a mesh screen and concrete troweled over it.
    Nice job though.

    [Reply]

    Ethan Reply:

    Hi Jay,

    Thanks for the comment. I’ll ask the guys next time I can about the potential problems. I will say they’ve been doing this a long time so I expect they’ll have a good justification for the way they did it.

    I asked them about using wire mesh reinforcements, and they said it wasn’t necessary for the pan (didn’t comment on the curb), and that they can easily puncture the membrane so they avoid using them.

    Hope to see you around OPC again.

    [Reply]

  • Christine responds...
    March 20th, 2013 2:17 pm

    How long does the cement in the drain pan take to cure before you can use the shower? (this is after the tile has been installed and grouted)
    Thanks,
    Christine

    [Reply]

  • Brett K responds...
    May 6th, 2013 7:55 pm

    If I’m not mistaken, there is supposed to be a preslope under the membrane to direct any penetrating water to the weepholes under the tile bed. The liner installed here is relatively pointless as any of that water that seeps through the grout or at the corners will just sit in the liner and not be directed anywhere.

    [Reply]

  • Matt C responds...
    April 17th, 2014 10:58 pm

    This looks great. Can the same method be used for installing a linear drain?

    [Reply]





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