Waterproofing Cardboard – A Supplement to The Cardboard Boat Book

What material to use and where to purchase it



This supplement provides an explanation of the waterproof coating that I use to waterproof cardboard boats. I have 2 boats that are over 23 years old that are still used to this day due to the excellent waterproofing properties of the coatings discussed here.

Acrylic Elastomeric Roof Coating

The recommended waterproofing material for cardboard boats is an acrylic base elastomeric roof coating. Elastomeric coatings can also be purchased with solvent bases. The acrylic base coating is the most desirable for waterproofing cardboard boats as this type of coating is environmentally-friendly. There are numerous manufacturers of acrylic elastomeric roof coatings. Elastomeric coatings can be purchased from local home improvement stores as well as purchased online.


Due to the number of acrylic elastomeric roof coatings available on the market today, and the fact that new products are constantly being developed, I have chosen not to specify any particular manufacturer. Instead I am providing a definition of the product, the properties that make it superior for waterproofing cardboard boats, and suggestions for how to find these products.


An acrylic base elastomeric roof coating is a “rubber-like” coating that provides the following  benefits/properties for waterproofing cardboard boats.

  • Dries to a “rubber-like” film.

  • 10 times the thickness of paint.

  • Won’t crack, peel, flake, chip or blister.

  • Long term exterior waterproof protection.

  • Fungus and mildew resistant.

  • Excellent UV protection.

  • Easy to use, non-toxic, and low VOC content.

  • Environmentally friendly.

  • Superior adhesion to cardboard.

  • Bridges hairline cracks.

  • Available in a wide range of colors and can be custom tinted with acrylic coloring agents.

Purchasing an Elastomeric Roof Coating

  • Research acrylic elastomeric roof coatings online by searching with the following search strings.
    - Elastomeric roof coating.
    - Acrylic elastomeric roof coating.

  • Decide on a few products that interest you.

  • Ask yourself some of the following questions to help make a decision.
    - Does the product come in a color or colors I want to use?
    - Acrylic elastomeric coatings can be colored with the color of your choice at a paint store that has the ability to color acrylic paint.
    - Is the product within budget?
    - Is the product available through a local reseller?

  • Ask your local home improvement store if they carry elastomeric roof coatings.

  • If you cannot find the product you are interested in at a local merchant then contact the manufacturer and find out where you can purchase the product online.

  • Purchasing locally will save shipping costs.

Bon Voyage!