How To Prep For a Walk-In Hot Mopped Shower Pan Part 2

How To Prep For a Walk-In Hot Mopped Shower Pan Part 2


Transforming your existing bathroom shower pan into a curb less walk-in type, will take a more than a little planning and thought! Your biggest and most expensive re-build will be how to achive making the shower pan floor lower than the rest of the bathroom.


You can see the almost feel the seamless beauty of a curb less walk-in shower!!!

Our last blog gave the mathematics of the what depth is needed for the size shower your planning ,but a nice rule of thumb is 3-1/2″ will work on showers up to a 5’x5′ with the use of a an adjustable style drain. If you calculate correctly you can minimize the depth needed, but remember being lower is fixable when it comes to finish heights and hot mop application’s, as extensions work wonders, being to high poses a major set back as the “fixes” usually are costly!!!

If your shower pan is going to be located on the ground floor and on a concrete slab, that is not a poured post tension, you probably have the easiest,(planning and execution of needed rebuild!) than with an existing wood sub floor.

Here are some basic guidelines on what needs to be done! Concrete slab first!

Once the size and lay out of your new shower pan in established it time to call the concrete saw and breaking contractor! I have seen many general contractors do this with their own crews. The results still needs to be the same…The slab that is cut out needs to be re poured or smoothed out at the proper depth!!!

Lets say you have decided to do your existing Master Bath 4’x4′ shower pan. The contractor will cut the area needed as close as they can to any existing walls and remove the the concrete by jack hammers. Some existing slabs are thick enough that only the depth needed is taken out, but that needs to be determined by your contractor. (Generally a 3-1/2″ to 4″ slab is the minimum allowed for strengh) More times than not the slab is totally removed and your base material and/or earth is exposed. This is then dug out to the depth needed to accommodate the new slab. For example: The slab cut out is 4″ average and you need to be recessed 3″, you would have to remove enough material to measure down 7″ to pour back a 4″ slab and retain your 3″ recess.

Note: make sure that the edges of the cut out slab are even/flush with all the bottom plates of your existing walls, this will be done with some “hand” work by your contractor as the original saw cuts may not be flush with the edge of the bottom plates due to the size and guards on the saw. This is very important, to be able to hot mop your shower pan correctly no lip or step can be less than 3″. You can also fur out the wall to match the first cut, but this will shrink your shower!!! A number of factors will determind which method(s) you will need to use.


In this picture you can see that although the depth is correct the edges are not flush with the bottom plate, this is where the “hand” work, is needed and the most common mistake in preping for your hot mopped shower pan; recessed!

Next your drain will have to be addessed; type, style, location and heighth, have been determinded before hand, so your plumber can re-route any piping needed.

Note: When installing a drain that is going to be close to any wall or recessed edge. The drain flange edge of any style 2″ drain needs to be set a minimum 1-1/2″ from the rough framing, or 5″ on center for a standard 7″ diameter drain body or 6-1/2″ on center for a 9″ commericial drain body. This applies to when you want the drain as close to a wall as possible to your finished wall as with a trough or liner drain, rised platform, or any “hidden drain” applications!



Here is some things to remember when planning your walk-in, curbless shower!!!

Plumbing may have to repaired and/moved after your slab is cut and removed.

The edge of the old slab needs to flush with you bottom plates, and smoothed to as flat a finish as possible, usuallly a skim coat or two of a rapid set thin-coat mortar does the job.

Check and double check that your recess is enough! Too low is an easier fix, too high poses a major head ache.

Dont neglect to do the standard prep for your hot mopped shower pan above the plate line!

Our next blog will give some details on how to recess wood framing!!!

Always remember to check with a reputable contractor and your local building department to make sure you are conforming with best trade practices and local and state building codes!


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