How to Frame a Fiberglass Tub

What You'll Need
.75-inch oriented strand board
2x4-inch wood plates
Measuring tape
Basic framing equipment
Fiber file
Filling glue

If you plan to construct a fiberglass tub yourself, you’ll need to support it with a frame that holds it together. No matter how lightweight the fiberglass tub is, it will need a frame because water makes the tub heavy. If proper frame is not provided, these tubs tend to crack. The framing is also necessary to ensure that the tiling fits the fiberglass tub perfectly. Follow the simple steps below to plan and build a frame for your fiberglass tub.

Step 1 - Layout

The most important thing to keep in mind when framing is to ensure that the plumbing that belongs to the new tub does not hover over the joint of the floor. Use chalk to draw an outline for the deck of the floor. Use erasable material for marking.

Step 2 - Placing the Plates

Cut the 2x4-inch plates for the side walls of the deck. The plates should be placed on the floor and the stud layout should be marked for convenience. Select proper placement for the tub before starting the installation. It should be done in a way that allows the layout to sit on top of the floor joists. Take extra care while marking, as precision is key.

Step 3 - Framing

Before framing the fiberglass tub, determine what height your tub is going to be. At the spot where the top of the deck cuts across the wall, chalk a line and nail a 2x4-inch plate into every stud, preferably with 16D nails.

Step 4 - Sheeting and Cutting the Fiberglass Tub Hole

The top of the deck must then be sheeted with .75-inch OSB and nailed. Use 8D nails, then consult the template. Set it somewhere convenient and transfer the outline of the fiberglass tub. Excess pieces can be cut out to finalize the frame’s construction. Use a fiber file to grind rough edges to give it a smooth finish.