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Installing Substrate Under Countertop

Tools Required

  • Cutting tool for plywood
  • Silicone
  • Hot Glue Gun
  • Level

Installing Substrate

  1. Identify and source substrate material (generally plywood) of the required thickness. The thickness will equal the height of the additional drop that was added to the countertop edge. (i.e.- If you added a 1" drop to create a countertop with a total edge thickness of 1.5", you will need to use 1" thick plywood).
  2. Cut and prep 2.5" wide strips of plywood.
  3. Measure and cut strips to length such that you fully frame around the inside edge of your countertop. Hold your substrate between 1/8" and 1/4" off of your buildup to allow room for expansion and contraction. Glue into place using alternating dabs of silicone and hot glue.
    Measure/Mark Cut Line

    Measure/Mark Cut

    Cut Substrate to Length

    Cut to Length

    Glue with Silicone and Hot Glue


    Glue with Silicone and Hot Glue

    Hot Glue

    Press Into Place

    Press Into Place

    The hot glue serves as a temporary bond that holds the substrate to the countertop while the silicone has time to fully cure. Never adhere your substrate only using hot glue. Silicone is absolutely required for a long term bond.
  4. Glue in horizontal 2.5" cross supports if remaining unsupported countertop depth exceeds 12". As a general rule you do not want greater than a 12" span of countertop without a cross substrate.
    Add Additional Cross Supports as Required

    Add Additional Cross Supports as Required

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