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How to Waterproof a Flat Roof Skylight

Step by Step Guide and Video of Skylight Installation on an EPDM Rubber Roof

Step by Step Installation Guide

Print these Instructions
  1. Mark Diagonally from Corner to Corner

    Using a straight edge and pen mark diagonally from corner to corner to form a cross and cut with a pair of scissors

  2. Position the Skylight

    Position the skylight over the opening. If the skylight is already in position prior to installing the rubber membrane the rubber membrane can be cut and then either lifted over the skylight upstand or an additional cut made to the nearest membrane edge.

  3. Cut Back Excess Rubber

    Cut Back Excess Rubber a minimum if 75mm from top of skylight

  4. Apply Contact Adhesive To Upstand

    Apply contact adhesive to skylight upstand and back of rubber membrane

  5. Bond Rubber to Skylight

    Bond EPDM rubber membrane to skylight upstand once contact adhesive is touch dry

  6. Cut Elastoform to size

    Cut 9" Elastoform to size and mark position on skylight corners

  7. Apply Rubber Primer

    Apply Rubber Primer

  8. Ensure Primer is Touch Dry

    Ensure rubber primer is touch dry before installing Elastoform tape

  9. Install Elastoform

    Install Elastoform starting at the top of the skylight and working downward stretching the tape as necessary


  10. Apply Pressure to Elastoform

    Apply pressure using seam roller

  11. Cut Cover Tape

    The 6“ Cover tape can be used to join the rubber membrane to the skylight upstand if flashing kit is not provided with the skylight. Cut to length ensuring a minimum 3 ” wrap around on corners

  12. Apply Rubber Primer

    Apply Rubber Primer

  13. Install Cover Tape

    Install 6“ Cover Tape. The tape should be installed equally on to the rubber membrane and skylight (3” on each) and apply pressure using Seam Roller. Lap Sealant can be used on the edge of the tape if necessary

  14. Finished skylight

    Completed Skylight Installation


Here's what you'll need