Shower Base
A shower base in a homemade shower stall constitutes all the layers of material that start from the floor of your bathroom and end with the floor of your shower. These layers include the pre-pan, pan and shower floor. Layers of mortar exist between each of these layers, as does metal lath. These layers combine to ensure that no water leaks through your shower floor and directly to the floor of your bathroom. Shower bases protect your home from structural damage.
Shower Pan
The shower pan comprises the middle layer in a shower base. It protects your bathroom floor from any water that leaks through the shower floor or around the drain. Shower pans consist of waterproof material such as plastic sheeting made of polyvinyl chloride or a liquid sealant. The pre-pan, which lays below the shower pan, sits between the bathroom floor and the shower pan. It anchors the shower pan. Technically speaking, metal lath is not part of the pan, but appears underneath and on top of it.
Metal Lath
Metal lath consists of a flat, mesh-like material made from metal, similar in appearance to a chain-link fence. It exists in shower bases to anchor mortar. Mortar constitutes a cement-like adhesive used to bind the layers of a shower base to one another. Mortar forms weak bonds with materials commonly found in bathrooms and shower stalls. Because of this, it needs an anchor to ensure that it dries properly and forms an adequate bond. Metal lath provides this anchor.
Do You Need Metal Lath?
Technically, you don’t need metal lath in your shower base or around the pan. Though metal lath helps anchor mortar used in building up a shower base and pan, the mortar itself should prevent deterioration of the shower floor. Lath appears more commonly in heavy-duty operations such as hanging stucco or mortar in heavy sheets from wood-frame walls. However, metal lath helps strengthen the bond between the layers of your shower base, increasing its durability and lifespan. Because of this, home improvement and construction books such as “The Complete Guide to Bathrooms” heavily recommend its use.