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Polycarbonate and Vinyl Building Panels by Onduline North America

TUFTEX® DeckDrain Installation Across Joists

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  2. IMPORTANT: Water should flow away from the house.
    TUFTEX DeckDrain panels may be installed to run perpendicular to the direction of the joists. This will allow for Slope Building Brackets to be installed on joists to create slope & direct water flow. The two functions of slope building brackets are 1: To provide a surface to attach the TUFTEX DeckDrain panels and 2: to direct water flow away from your house. If you want to install the TUFTEX DeckDrain panels to run parallel to the joists, please follow the instructions for TUFTEX DeckDrain Installation Along Joists. If you have questions, please call us at 1-800-777-7663.

  3. DeckDrain Traditional Method Installation - slope stripe applied perpendicularESTIMATE YOUR NECESSARY MATERIALS:
    1. Panels: Multiply (A) X (B) to get the total number of square feet of your deck (See Fig A) and add approximately 10% for end laps. Divide by two (2) to get the number of linear feet of TUFTEX panels needed. Then divide by length of the TUFTEX panels and round up to the next whole number for the approximate number of panels you will need.
    2. Slope Building Brackets: These are the brackets to which you will attach the TUFTEX panels. They are 4’ in length and can be easily cut to fit your deck. To determine the number of brackets you need, multiply 1/2 the number of joists in your deck by the length of one joist. For instance, if you have 16 joists and they are 10´ long it would be 8 (joists) X 10 (feet) = 80 feet of bracket. NOTE: You will attach a slope building bracket to every other joist starting with the third joist from the edge of your deck. (See Fig C) Be aware that you may need to attach brackets to additional joists. (See Figs D & E) It’s advised to plan your job then purchase your brackets & other materials.
    3. DeckDrain Fasteners: It will require approximately 30 TUFTEX DeckDrain fasteners to properly attach each 10´ TUFTEX panel. More fasteners may be necessary in climates where heavy icing may occur. REMEMBER: 1 box equals 100 fasteners. No pre-drilling required.

    DeckDrain Traditional Method Installation - Necessary Materials

    To prepare to attach your TUFTEX panels, start by attaching Slope Building Brackets to joists.
    1. Slope Building Brackets: Building a slope is necessary to keep water from accumulating on the panels and to divert it away from your house. Because most deck joists are not level, follow the tip in (Fig B) to help create a steady, even slope. To build your slope, following this simple tip, start with the third joist by attaching the measured & cut slope building bracket using ordinary deck screws. This first bracket will be slightly lower than the bottom side of the end joist, thus, creating slope (Fig C). You will attach a bracket to every other joist, working your way across from that third joist, to the opposite end (Fig C). Each time you attach a new bracket drop it slightly to rest on the string to achieve your slope. This slope should work out to be a minimum of one inch (1˝) drop for every 10´ of run.
      IMPORTANT: Building your slope is necessary for the proper draining of rain water away from your house. Also, if overlap occurs where there is no slope building bracket (Figs D & F) you will need to add a slope building bracket to an additional joist at the overlap point and secure with fasteners.

    2. DeckDrain Traditional Method Installation

      Figure B: Example of slope strips applied perpendicular to joists.

      DeckDrain Traditional Method Installation - Building Slope

      Figure C: Building slope.

    3. TUFTEX® Panels: In most cases, joists will be 16˝ on center therefore, the use of 10´ TUFTEX® DeckDrain™ panels are recommended. Begin the first row with a full panel. This first panel will fasten directly into the outside joist (See Fig D). After the first joist, the panel is secured to slope building brackets, attached to every other joist, as indicated below. Subsequent panels should be cut to a length which will place the overlapping panel end at no less than 4˝ (usually greater) beyond the back of the underlapping panel. This is called “end lap” (See Fig C). The underlapping panel should start as shown in Figure C so water will not seep & drip between panels.
      REMEMBER: DO NOT be tempted to shorten the end lap. Shortening the end lap may result in leaks.
      IMPORTANT NOTE: We recommend using a vinyl adhesive on panel overlaps to maintain a watertight seal.
DeckDrain Traditional Method Installation - slope stripe applied perpendicular

Figure D: First Panel Installation

    DeckDrain Traditional Method Installation
  • Attach first panel to slope building brackets (See Fig D): Wait to install the side lap and end lap fasteners until subsequent panels are installed.
  • Attach second panel (See Fig F): After fastening all but the lap sections of the first panel, place the second panel in the row below the first and begin fastening at the end lap. Fasteners will be used in every other corrugation, and staggered between brackets (See Figs D & E) while fastening the panel directly to the slope building bracket.
    REMEMBER: DO NOT fasten the corner which will have the lap side
  • Begin second row:: After completing the first row you can start the second row by using the cut off remainder of the last panel from the first row (provided it is at least 4˝ longer than the distance between joists). After securing the cut panel you can continue the row with full panels to the end. This method of staggering end laps will help avoid having 4 pieces come together in one place. The second row of panels will overlap the first row and the side lap should now be fastened. Remember to leave the other side unfastened until you install the third row (See Fig F). Proceed with fastening and lapping as with the first row. Repeat the above for each subsequent row.
DeckDrain Traditional Method Installation

Figure F: First row of panels.

DeckDrain Traditional Method Installation - Optional Bracket Attachment


  • If your deck is large, pitch it two ways from the center.
  • To increase water tightness seal end laps with vinyl adhesive caulk.
  • Gutters can be installed to collect and direct water from panels.
  • Use opaque panels. Translucent panels will show underside of deck.

Tools Needed for This Project

  • Tape Measure
  • Drill with 1/4" hex driver bit
  • DeckDrain screws
  • Heavy duty snips or circular saw
  • Vinyl adhesive caulk
  • String

While panels are non-flammable, be careful as excessive heat rising from barbeque grills being used on patios or decks with TUFTEX® panels installed above may deform or warp panels.

Questions? Call 800-777-7663


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