Tiled up for Jaccuzzi
Larger bathtubs, such as Jacuzzi tubs, have an actual tub deck that creates a platform around the tub, rather than just a normal frame that accommodates only the tub itself. The deck can be covered with a variety of materials, but most common is natural stone and man-made tiles, just as on floors and walls within bathrooms. Some structural reinforcement may be required to shore up the deck, but otherwise you can tile any way you see fit to cover the bathtub deck.
- Platform Framing
As a general rule, large tubs are primarily supported by a foam or mortar base that is set with the actual tub under its bottom. The edges will carry some weight, but it is usually negligible, which means the edge sitting on top of the deck platform won’t transfer much deflection (up and down movement) to the deck. However, the larger the expanse of the deck platform, the more support will be required underneath. The deck needs to be a minimum of 3/4 inch exterior grade plywood and if the platform extends more than 16 inches past the initial exterior frame, you must include another row of framing to support the deck around the edge of the tub. Tub framing is two-by-four material cut down to size with a header, footer and vertical supports every 16 inches, screwed down to the subfloor and joists where applicable.
- Concrete Board
Concrete board is installed on top of the plywood decking and must be adhered with mortar as well as nailed or screwed down every 4 inches across the surface. A 1/8 trowel provides sufficient coverage, but you can go as large as 1/4 inch. 1 1/2 inch wood screws or roofing nails are used to attach the board. You can also use a concrete-based fiber-board in place of a concrete board. If the tub is preset and you are building up to the underside of the edge, you will need to estimate the thickness of the tile, mortar, underlayment and mortar to ensure that all of your layers will fit underneath. Give at least 1/8 inch for each layer of mortar after compressed by tile or underlayment.
- Waterproofing and Caulking
The concrete board needs to be waterproofed prior to installation of the tile. For preexisting tubs or top-set tubs, this means installing the board, applying the waterproofing, installing the tile and then caulking the tub in. Existing tubs that are flush with the platform with tile running up to the edge need to have a 1/8 inch joint around the entire perimeter of the tub where the underlaymet terminates, which is filled with caulk after the installation. You can use paint-on waterproofing or a peel-and-stick membrane for ease of use; the goal is to waterproof the entire surface of the underlayment, as well as several inches up the walls.
- Before or After
There are two ways to tile a bathtub platform: before and after. The preferred method is before the tub is set, which allows the tub to then rest on top of the finished tile surface, giving a seamless look to the installation. However, some tubs are already in place and require the tile to terminate around its edge. There is no structural difference in the two, but if you must cut the tile to the tub, be sure to allow for expansion and movement via the 1/8-inch joint that carries up into the tile installation as well. As far as layout goes, you can tie the platform installation into the floor/walls and carry the joints up throughout, or you can use a different bullnose edge and completely separate the platform layout, such as centering it on top of the platform.
- Adjusting Height
For tubs that are already in place, but have space under the edge, you have some flexibility. You must include a layer of plywood plus a layer of underlayment. However, if you see that a 1/2-inch underlayment will not give you sufficient space to also include your tile, you can downgrade to 1/4-inch board. Alternatively, if you are a little short even with the inclusion of a 1/2-inch board and the thickness of your tile, you can build up the overall levels with a larger notched trowel to apply more mud. The tile should ideally finish flush with the underside of the tub edge, but can also terminate slightly under. In both cases, this edge is caulked after tile installation.