Back Button

How to Treat Old Masonite Siding

Richard Bonilla

Masonite siding is a synthetic material made from wax and wood fibers. Primarily used in the 80's and 90's, Masonite siding was the preferred method for designing the exterior of a house. However, Masonite siding has proven troublesome to maintain.

Masonite siding can crack and damage if it is not maintained properly.

It requires constant upkeep to prevent molding and cracking from occurring. Still, home owners can maintain their Masonite siding by cleaning, chalking and repainting it.

  1. Power wash the exterior of the Masonite siding. Power washing removes mold and dirt, allowing for proper paint adhesion. Set the power washer to 1500-3500 psi. Insert soap or detergent into the washer. Stand at least six feet away from the Masonite siding while spraying. Be sure to spray the entire exterior of the house that has Masonite siding.

  2. Allow the house to dry for 24 to 48 hours before caulking. If you caulk too soon, water may still be present inside of cracks, causing improper drying.

  3. Check for cracks and nail holes and indentations. Insert the caulk into the caulking gun. Fill any cracks and nail indentations; nail indentations cause cracks and should be filled to prevent further damage to the siding . Be sure to caulk at a 90 degree angle.

  4. Prime the Masonite siding if necessary. If your Masonite siding has several indented nails and the bottom of the siding is spongy or chipping, apply a primer coat. Applying a primer coat is not necessary if the Masonite siding is well maintained.

  5. Paint the Masonite siding. Painting Masonite prevents the siding from cracking open. Be sure to apply two coats of paint and always paint top to bottom and side to side. For a quicker and cheaper method, paint using a paint spray gun to lower the cost of paint.