How To Prep For a Walk-In Hot Mopped Shower Pan Part 3

How To Prep For a Walk-In Hot Mopped Shower Pan Part 3


Well here we are again! Had plenty of Walk-in hot mop shower pan issues since my last post! Nice to say that the last blog covered most of the problems that the clients had!!!


Looking at this picture, you can see why so many people like the seam less beauty of a walk-in shower!

We discussed how to accomplished the “recess” needed in a concrete slab in our last blog.

The mathematics and minimum clearance remain the same, just how to get that in wood framed construction will take a bit more planning and work.

Our main concern is when we recess the floor it is going to take some of the strengh of the framing members that support the floor away…we need to make sure that we are not compromising the structural integrity, the bearing weight that the floor joists are designed to take when first built…in new construction this is easily done and has been designed to do so by the architect when he drew up the plans or revised when asked for the change…in remodeling cases, its a different story…here is where a good general contractor is appreciated!!! you will need to find out what is holding up the floor (size of floor joists and type) and how much you will need to reinforce and/or replace to achieve the same bearing weight needed and still get enough recess in the floor…whew… a mouth full there!!! It would be nice if you just notch and trim down the floor joists where you need them, re sheet the floor and wha la ready to go…not that easy but that is where you need to start your thinking!!!

As with any project Hot Mopping is no different!! The better the preparation the the easier the following work can be performed. Sharp clean corners and transitions, backing securely fastened, nail and screw head countersunk, drain set and secured, will give you a long lasting, trouble free hot mop.

Having access to the work area is one priority! When you are down to bare studs and floor you can now find out what you have to work with.

Removing the plywood sub floor and finding out the size of your floor joists is where to begin.

The standard depth needed for an adequately recessed for up to a 5×5 shower or less, will be 2-1/2″ to 3″

You have determined that you have 2×10(actual size 1-1/2 x 9-1/4) joists and need to have a 3″ recess. The cut out on the old joist will reduce it to 6+ inches. Taking away a major part of its bearing capabilities. This serves only as an example for solid wood floor joists. Many home here in southern California are built with TGI, or other manufacturer of I joists, these system have special considerations, and it best advised that you contact the manufacturer and/or use a qualified contractor for any alterations needed.

Reinforcing these framing members can be done in a number of ways. One thing to remember is that anything added or replace needs to be supported in an approved way for it to accomplish the support that is needed…

Here is were a good general contractor is appreciated. Just nailing on a extra 2×4 to the cut down 2×10 is far from “getting it right” it may prove easier and less costly in the short run, but taking improper short cuts has always proved to be unsafe and expensive in the end.

Sistering up (adding wood to wood) may be part of what is needed to get it done right! A number of things need to be considered.

Do both sides have adequate support for add-on lumber with-in your working area, that would be bearing walls or beams that joists can be attached too. Usually you will have one easy side and the other will present some difficulty!

If possible removing the ceiling under your shower pan area helps, and can actually save money, in most case,s than tring to do all the work from above.

Using a different dimensional lumber can also be part of your solution, as wider in width but shorter in height can really be the ticket to achieving that recess that you need! Spacing also makes a difference, your standard floor spacing is 16″on center shorting it to 12″ or smaller may give you the added strength you need! Make sure that you have someone who is qualified to give the proper size of lumber to do replacement to give you the same stuctrual strength you need.

Your joist lay out may not cooperate and you may have to totally removal a portion of the joists, add support beams or doublers to carry the new smaller(height), fatter(wider), tighter spaced floor joists. The good news is that you can determined all of this after you remove the sub floor and maybe a small section of the ceiling below.


Seems like a whole lot of work!!! More and more people are staying in there homes longer and remodeling the bathrooms is usually way up there on the list! With all the effort that goes into making your recessed shower pan ready for hot mop. Either for the beauty and elegance, or for the practicality you need for ease of access for yourself or a relative, using the hot mop method of waterproofing has proved itself time and again for its excellent protection and durability…Enjoy your new walk in shower…Nothing like a long shower at the end of our busy days!!!


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