How to Install Wallboards for Tub Enclosures

Apr 29 2022

HYDRO-BLOK Wallboard for Tub Enclosures

Before Installing your tub & HYDRO-BLOK Wallboard

Ensure all plumbing and wall studs are in the required locations before beginning installation. Check to ensure the floor and wall studs are secure and add any additional blocking at this time if required (the tub manufacturer’s instructions will provide a detailed drawing of the recommended wall stud placement). If your tub does not come with a pre-moulded flange as shown in the instructions below, you must install a waterproof tub flange for tile as specified by the manufacturer of the tub and your local building codes. Ensure that the tub is securely fastened in position as per the directions from the manufacturer. NOTE: ½” and ⅝” HYDRO-BLOK wallboard must be installed with a maximum stud opening of 16” OC. When fastening the tub to the wall studs, ensure the screws used to aach the tub flange to the wall studs are counter sunk and flush with the flange.

Installation Tools and Materials Required

• ½” to ⅝” HYDRO-BLOK Wallboard
• HYDRO-BLOK Washers and Screws
• HYDRO-BLOK Joint Sealant (HYDRO-BLOK Sausage gun or Skeleton Gun are recommended)
• Puy knife (flat and corner blades recommended)
• Cordless or electric drill with a #2 Robertson or #2 Philips screwdriver drill bit
• Tape measure and marker/pencil
• Sharp utility/razor knife and metal straight-edge
• Cleaning supplies (we recommend paper towels, citrus wipes, rags, dust pan and brush)

IMPORTANT: Please read all related installation guides before installing your HYDRO-BLOK products! Contact your local dealer if you have any questions regarding the installation process.

1) HYDRO-BLOK Wallboard should be first installed on the back wall of the tub enclosure followed by the sides. Begin installation by carefully measuring and cuing the required wallboard pieces. For vertical dimensions, measure from the deck of the tub to the top of the wall and then subtract one ⅛” for the required gap between the wallboard and the tub deck.

figure 1

2) If your tub flange is greater than ⅛” deep, a notch will need to be cut into the wallboard in order to allow it to fit flush against the studs (see Figure A). Measure the height and depth of the tub flange and use a sharp utility knife and straight edge to cut a notch into the boom of the wallboard (see Figure B). The notch should allow the wallboard should to rest plumb against the wall studs and be square in the corners. Dry fit all wallboard first to ensure it fits properly

figure 2

3) Apply two, ¼” continuous beads of HYDRO-BLOK Joint Sealant to the tub flange along the entire back side of the tub. Apply one ⅜” continuous bead of joint sealant on the tub deck right next to the tub flange so the wall board can be pressed down into this bead. (see Figure C – side flange is shown) Press the lower edge of each wallboard panel into the joint sealant bead on the tub deck and then press it against the back wall and the joint sealant on the tub flange.

figure 3

4) Begin aaching the wallboard to the studs using HYDRO-BLOK screws & washers starting approximately 4″ up from the tub deck on all stud locations (see Figure D). Continue to install screws/washers every 12″ up each stud location. Do not install the uppermost screws/washers until the all rear wallboards have been installed.

figure 4

5) If multiple boards are required, install them by first applying a ½” continuous bead of HYDRO-BLOK Joint Sealant along the edge of previously installed wallboard (for horizontal and vertical joints). Install the next wallboard by gently lowering and pressing it into the bead of sealant. Secure the wallboard with screws & washers starting 12″ up from the seam. Once the wallboard is secure, add screws and washers at each stud location along the seam. Use a HYDRO-BLOK standard puy knife to smooth out the excess joint sealant along the seams, using it to cover the seam as well as the screws and washers.

6) The side wallboard panels may now be installed in using the same method as the rear panels. Be sure to measure and mark the location of all plumbing fixtures carefully. Use a razor knife or utility knife to cut any required openings on the wallboard before installation.

7) Begin installing the side wallboard by applying a ½” continuous bead of joint sealant on the edge of the rear wallboard where the side panel will join. When placing the side panels in position, ensure they are firmly pressed into the joint sealant on the rear wallboard as well as the joint sealant on the tub and flange. Continue by using screws & washers to secure the wallboard at all stud locations as described previously. Use a HYDRO-BLOCK corner puy knife to smooth out any excess joint sealant in the corners where the sides and rear wallboard meet.

8) Once all wallboard is secured, add ½” dabs of joint sealant on all washers and use a HYDRO-BLOK standard puy knife to ensure each washer is covered by sealant.

9) Apply a continuous ½” bead of joint sealant on all wallboard seams and smooth out again with the corner puy knife to fully cover the seam. Ensure there is at least 1″ of joint sealant on either side of any seam. (see Figure E)

figure 6

10) Clean any excess joint sealant from the tub surface with mineral spirits or citrus wipes. Aer approximately one hour, (at room temperature of at least 18° C or 65° F) the joint sealant will skin over and thinset can safely be applied.

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