Waterproof membranes for bathrooms are used for protecting the underlying subfloor from the infiltration of moisture. Your subflooring will be of concrete or wood (generally, those are the two most common building materials for that situation). In either case, you do not want water building up on it. In the case of concrete, the water will sit there and promote the growth of mold. This can lead to bad odors and health problems. With wood, there is the added risk of rot.
Waterproof membranes for bathrooms are vital when using a trench drain. Yet, some people may ask, why use a trench drain at all? It is a valid question; after all, regular drains have been used for years and are perfectly fine. Well, it has to do with two factors: safety and access.
When you have a regular shower, it has a raised edge to it. Even if it is only two or three inches, it is still an edge. And, all it takes is for one person to trip over it and down they go. This can lead to injury, and even litigation and that is the last thing anyone wants.
Also, as the baby boomers age, there is the issue of access for the elderly. On top of that, if anyone in your household is disabled and uses a wheelchair, that small ridge will seem like a mile high mountain to them. So, making use of a trench drain starts to make sense, when you look at all the factors involved. Also, there is no need to worry about flooding your bathroom; a properly installed trench drain will catch every drop from your shower.
Tying the Membrane in to the Drain
So, when installing a trench drain, you will need waterproof membranes for bathrooms. You select one that is appropriate for your situation, and then install it between the subfloor and flooring. As to which type to use: thickness etc. you will want to consult with your building department, or at least a plumber, to see what they recommend.
At the very least, the membrane should extend underneath the whole bathroom floor and also go up the walls about four feet. The critical areas, the ones where leakage can most likely occur, are at the drains.
When you think about it, it makes perfect sense. A drain, whether for a sink or toilet, is a hole right through the floor. So, it is the ideal place for water to collect. Therefore, waterproof membranes for bathrooms are used to address these situations. In the case of a toilet drain, the best type of membrane to use is what is known as an upturned sleeve.
With the trench drain, that calls for a little more finesse. You will need to use what is known as a membrane clamping collar (with weep holes). The way it works is this: you have the drain line going down through the flooring. From the trench drain, a coupling will come down to a short section of PVC piping. The membrane clamp goes around this piece of pipe and then the pipe connects to the drain line. Then, any of the various waterproof membranes for bathrooms is held by the clamping collar.