The shower bench is a very functional component of your shower that also provides a luxurious amenity during usage. It becomes a focal point but doesn’t deter from the rest of the shower area design.
The shower bench frame is most commonly constructed during the shower curb or shower pony wall build out. You can build the shower bench of cut to length wood pieces, preferably pressure treated, and installed into the desired area. Before you choose to use pressure treated wood, it is important to understand that it will dry out and can be prone to twisting, therefore, you will need to determine if its the right choice for you and within the building code requirements in your area. Placement of the shower bench often is removed from the entrance and opposite of the shower fixtures, but your personal preferences will determine where is best for you. It is also important to understand that the shower bench has a potential to pool water, therefore, where a horizontal plane exists, some shower benches have multiple, these should have a negative pitch into the shower area. The intended goal is to discourage water from pooling and encourage it to run downward and into the shower area.
There are many ways to provide structure to the shower bench to ensure that that finished product is both sturdy and safe for usage. First, blocking the shower bench with cut to length wood pieces in between the frame will provide extra rigidity. Another option would be to build the shower bench over cinder blocks, stacked according the desired height and length and within the frame. The shower bench finished product should be securely attached to a single or multiple shower walls and not have any opportunity for movement. It should also be able to withstand the average weight of those that will use it normally during a shower.
Your waterproofing strategy will be carried over into the shower bench, taking into consideration the design and where the greatest potential for water pooling can occur. The shower bench holds the distinction of being in the immediate shower area, therefore, it often is provided the same water resistant barrier as the shower pan. As an example, if you chose to install a PVC shower liner in your shower pan, than this would be carried over to the shower bench as well. The strategy is to capture any moisture in the shower area, including the shower bench, and not allow it to reach behind the shower walls. The shower bench does provide a difficult challenge to overcome, since it often times has many forms, from height, length, and different planes of motion.
Cement Over Bench
If you choose to apply cement over your shower bench, it will have to be done with your entire waterproofing strategy in mind. For instance, the 15lb. felt paper used under the wire mesh that helps suspend the cement scratch coat, will need to be laid under the water resistant barrier used behind the shower walls. In this scenario, a 15lb. felt paper will be the water resistant barrier chosen and installed behind the shower walls. Another complication is the different planes of motion on the shower bench and the joints where it meets the shower walls, this is where vulnerabilities will be present and an increase in risk of moisture exposure.
Backer Board Over Bench
You can successfully install backer board over the shower bench but you will need to take into consideration where pooling water and moisture leakage can occur. Backer boards are not water resistant, therefore you will need to have given thought about your shower bench when choosing your waterproofing strategy. Whether you choose to install a water resistant barrier behind the backer board or to the exterior, you will still need to ensure the screws and joint seams are mud packed with a thin set, deck mud, or silicone, and a fiber mesh that is alkaline resistant.
You can choose to install a pre-manufactured shower bench that is often in the form of natural stone or even from modern components. In this case, the same rules apply, as the shower bench will still sit in the shower area, the pre-manufactured version should be installed to ensure that water pooling does not occur and moisture leakage into the shower walls is not allowed.