KAYU Tongue & Groove Porch Flooring Installation Fundamentals

Fundamental Guidelines

We’ve outlined some fundamental guidelines to assist you with the process of installing your KAYU® Hardwood Product, being mindful that each project is unique and the details vary from build to build. Please consult with a professional siding installer in your area.

All wood is subject to expansion and contraction as the moisture in the environment surrounding the wood changes. KAYU® decking is skillfully kiln-dried, board to board, resulting in highly consistent results. Shrinkage is very limited, unlike air-dried boards.

Ventilation and Air Flow

  • Building codes are constantly changing and they can vary by state, county, city, town, and/or district. Contact your local Building Inspection Department to ensure compliance of flooring installation.
  • Allowing adequate ventilation is extremely important for proper air flow to reduce the potential for cupping and surface checking. In high moisture areas, it is imperative to leave an expansion space; allowing the wood to expand and contract. In high moisture areas do not install the flooring tight, leave a minimum 1/16” expansion gap between each board.
  • Moisture underneath a non-ventilated floor will be absorbed by the bottom side of the board while the sun and wind will dry the top side of the board. This unequal moisture content will cause cupping.
  • For maximum long term porch flooring stability:
    • Slope the soil underneath the porch away from the center.
    • Install a moisture barrier on the ground underneath the porch.
    • Leave 2 feet of exposed soil around the perimeter under the floor.
    • Build leaving a 1⁄2” expansion gap at the wall of the house and use trim board to cover.
    • Slope the flooring 1⁄4” per foot away from the house.
    • “Vent” (leave 1⁄2″ space around) columns/posts allowing for movement of flooring, covering with trim. If the flooring expands,it could move the columns/posts.
  • When KAYU®-Tongue u0026amp; Groove is being installed as a Soffit, we highly recommend a polyurethane adhesive in addition to Fasteners due to the weight of the hardwood.



  • Pilot holes are recommended to prevent splitting, especially on the end of the board; using stainless steel with 7d or 8d finish nails. Blind nail through the tongue at about 45°. The nail must penetrate the joists when face nailing within 3⁄4” of the edge or end of the board. (see diagram below).



  • Safety should be one of your main concerns when installing flooring. We recommend wearing protective eye-wear, dust masks, and gloves during installation. When using a saw, always cut away from your body. Check with your local department of Building and Safety before you start a project and/or have safety concerns.


Storage and Handling

  • Before installation and finishing, keep your KAYU® hardwood floorboards clean, dry and out of direct sunlight. Acclimate to your project site by dry-storing 2 weeks prior to installation. Do not store siding directly on the ground. Be sure the bottom boards are well ventilated by placing the boards at least 12” off the ground and on top of blocks. Do not cover siding material with plastic or tarp during the acclimation period, this will trap moisture and cause stability issues. Place a sheet of plywood on the top of the pile to shed any water. Do not store the wood in an enclosed area (this includes warehouses, garages). Keep material dry until installation.
  • Do not cut Metal anywhere near KAYU® Hardwood during the installation process, avoiding MPCC (Metallic Particle Corrosion Contamination).


Sealing /finishing

  • Prior to installation, seal Porch Flooring with a high-quality penetrating oil sealer on all four sides. Sealing only one side will create uneven moisture flow which increases the likelihood of cupping.
  • In order to bring back the original color of the deck, a periodic cleaning and a new coat of finish will be necessary. The rate at which maintenance is needed depends largely on; the degree of exposure to direct sunlight, climatic conditions, preference of deck color and the frequency at which any preservative treatments are applied. However, Once a year is the standard guideline for maintenance.
  • Similar to other exterior wood products, with time, KAYU® Hardwoods will gradually fade to a silver-gray patina color. If this is preferred, leave all four sides unfinished and allow to weather naturally. In this state, maintenance will be as minimal and easy as any other decking product on the market.



  • KAYU® decking is skillfully kiln-dried for consistent application, board to board, using a highly sophisticated process of computer and operator controlled heat and humidity to adjust and regulate the drying of the lumber. Excessive moisture will cause the boards to expand slightly. Unlike air dried boards, shrinkage is very limited. Please refer to our website resource pdf. about why kiln drying is far superior to air-dried.
  • KAYU® decking does not shrink or expand end to end (unlike composite decking), therefore neatly trim ends and butt together.


Maximum Allowable Decking Spans for Porch Flooring:


We recommend narrower spans, for a sturdier Hardwood floor


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