Number two in this series of blogs on the pros and cons of the different systems that are available to you to waterproof your shower pan. This is a very popular one. Hot mop vs cold applied liquid membranes! As with the previous blog we will lay a little groundwork before we proceed.
Commonalities of all systems
When comparing the different types of systems to waterproof your shower pan, we need to take a look at what they all have in common before we can hash out the advantages and disadvantages of each.
The carpenters will be in charge of making sure that the shower pan has all the proper backing and blocking (link to blog) needed for the correct installation. Any benches, seats, soap niches, and curbs usually fall in their scope of work. All waterproofing techniques require a solid surface to which the material to be used can adhere too. Gaps and voids create a weakness to the overall performance of the product that is being used. Those gaps and voids that are just bridged in the installation process stand a good chance of being penetrated by others working in the shower pan area.
Plumbing
The plumbers will be in charge of setting the drain and water supply lines. This can be done before or after the framers do their job. The importance of using the proper drain and placement is a critical part of the scope of work when it comes to the finished product. Drain styles and options have evolved and have given the client and/or builder a new dimension in what the finished product can look like.
(see drain blog)
The Pre-Slope
Whoever is doing the waterproofing usually does the pre-slope but not always. The importance of establishing the proper slopes (both pre slope and set slope, see blog for more info) cannot be over emphasized! Improper slope has caused many a headache for contractors and DIYers alike. The building code for pre-slope has set parameters, ¼”to ½” per foot no less and no more, beware though some cities and counties and individual inspectors prefer the use of the maximum amount per foot, as is the case for LA county and many of the surrounding cities in the Los Angeles basin. Inspectors have failed pans for not having enough pre slope, even when within the building code parameters! The pre slope is to be made of a material that forms a smooth, solidly formed subbase to accept the lining material. This gives a wide range of materials that can be used. I will go into more detail on pre slope differences and how they are made in a future blog. For now we have what most showers (there is some exceptions and it is the load bearing sheet good applications for waterproofing your shower pan that combine the pre slope and set slope in one…more on that in the future as we compare the other types of products that can be used to waterproof your shower pan)
Now that we have all the commonalities of what these systems need it’s time for the comparisons in their applications…
Cold Applied Liquid Membrane Products
There are a lot of cold applied liquid membranes on the market the most well-known is RedGuard by Custom building products and is available at most home improvement retail outlets. Laticrete’s Hydro Ban is also very popular with contractors, as is MAPEI’s Mapelastic. Availability is not as common as with RedGuard but all of these products work in pretty much the same way with each having its own special needs or preparation guidelines to follow.
The Application
Cold applied liquid system is in the category of direct lay systems, meaning that tile can be directly laid to it with your bonding adhesive, which in the tile world means thinset mortar. This means that your walls can be covered with whatever backer units or method you have chosen before the material can be applied to the shower pan. Some of the products used are Hardie-Backer, probably the most popular. Cement board, DensShield are a few types that can be used as a stand-alone product, others like Kerdi-Board and Wedi recommend using their total system for best performance and warranty! Once tile backer board unit are installed and the pre-slope is done. The waterproofing can begin. Always follow the installation procedures with all the products being used. As stated earlier each will have its best practices guidelines. Surfaces should be clean, set and cured as in the case of the pre-slope, and free of moisture in most cases. Some call for a filler at the transition from the pre-slope to the wall or a mesh tape imbedded in the product being used. Now it just a matter of painting the product on all the surfaces to be waterproofed either with brush, roller or both. A certain thickness is required in all cases and with some certain types of caulking are needed to connect the drain together. Additional coats over the 2 coats that are recommend to meet ANSI A118.12 building code compliance at the rate of 50 sq.ft. per gallon, this may vary with different products see each respective data sheets for up to date specifications) can be applied and missed spots or holes can be touched up. Dry time is very important prior to water testing.
Here are some or the pros and cons of this system
PROS
- Readily available at many retail and online vendors
- Comparatively inexpensive a mid-range cost
- Can be done by an experienced DIYer
- Fairly quick installation time with the right conditions
CONS
- Application delay when setting over a mortar based pre slope, pre slope needs to be set hard, as smooth as possible, and dry. Fast setting materials can be used but this increases project cost and can be difficult to work with
- Caulks and/or specialty tapes may be required at flat to vertical transitions and at wall corners
- Drain flange connections may need specialty caulks or other application methods for proper adhesion
- Dry time between coats and for water testing
- Getting proper thickness when applying and after cure for best performance
Hot Mopping Application
Hot mopping is a monolithic system that uses asphalt impregnated perforated felt paper and hot asphalt (tar) to form a built-up system of 4 layers of tar and 3 layers of paper. It is bonded to the pre slope and to itself to form what is essentially a one-piece waterproof layer that can conform to almost any size and shape including odd angles, rounded and cut corners are not an issue. All seams, laps, and corners are bonded to each other by a generous layer of hot tar. Wall to floor folds are crisp and clean and stay in place. Benches, pony walls, and tub ledges blend cleanly into your shower pan creating an integrated coating of all the areas being waterproofed. All corners, wall and curb seams receive a fiberglass mesh for added strength before final topcoat of tar.
PROS
- Fast installation time when performed by a qualified technician standard 3×5 shower can be completed in 90 minutes or less.
- No waiting for mortar bed pre slope to set for installation
- Square and clean corners as material is adhered to pre slope and backing
- Multi layered system adds superior protection
- Able to do large areas and custom shapes
- Water test in as little as 3 hours after completion
- Cost is very competitive with all other methods of waterproofing
- Can be used for decks
CONS
- Specialty contractor needed to perform job
- Fumes, smoke, steam during installation
- Tar smell when applied dissipates within 45 minutes depending on ventilation
All waterproofing systems work when applied in the proper manner. Some are easier than others. Hot mopping has been used in Southern California for going on 60+ years or more. It has proved its dependability and remains the 1st choice for builders and contractors. When you or your builder hires a licensed contractor to hot mop your shower pan that is usually all that company does. Day in and day out experienced technicians that are focused on their trade and making your shower pan waterproof for years to come.
Summary
Article Name
Hot Mopping vs. Cold Applied Liquid Membranes For Showers
Description
Number two in this series of blogs on the pros and cons of the different systems that are available to you to waterproof your shower pan.
Author
Jonny Gautney
Publisher Name
DK Shower Pans
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