How to Repair Hardboard Siding

Hardboard siding is a popular and inexpensive siding material made of plastic risen and wood fibers. It is installed on the exterior walls of a house and serves as a protective barrier against outside elements such as heavy rain, snow, moisture and heat. Overtime, a hardboard siding needs to be replaced due to moisture damage such as molding and softening. Repairing a hardboard siding is easy with the following materials and instructions.

Step 1 - Check the Siding Panels and Clean the Holes

Check the siding panel for molds, holes or any damage. The siding panels nearest to the ground are usually the first to mold. Remove the siding panel that is damage and install a fresh hardboard siding panel. Remove the damaged siding panel using a claw hammer and extract the nails left on the wall from the old panels using tin snips.

Measure and cut your replacement headboard siding with a jigsaw. Lay the new panel into the wall surface where siding replacement is needed. For vertical siding panels, nail every 8 inches around the borders of the siding panel to secure the siding panels firmly on the wall surface. For lap boards, nail at the upper portion of the panel and hammer the lower portion into position to secure and level the new siding panel  to the surrounding siding panels.

For siding panels with only a few holes, clean the area around the holes with a small wire brush to prepare it for the next step.

Step 2 - Apply Filler Compound

Apply filler compound to the holes in the siding using a putty knife. Use a pre-mixed filler compound that you can purchase at your local home improvement depot. Fill successive layers of the filler compounds on large holes and use adequate amounts on small holes. Allow the filler compound to dry before proceeding to the next step. Different pre-mixed filler compound have different drying times. Check the product label of your filler compound to determine the manufacturer’s recommended drying time for your type of filler compound.

Step 3 - Sand the Area

Using a fine grain sandpaper, sand the area where you applied the filler compound. Continue sanding until the filled area is level with the rest of the hardboard siding surface.

Step 4 - Paint the Siding

Check the rest of the hardboard siding for paint peelings. Remove the peelings using a scraper. Use sandpaper to smooth and even the entire hardboard siding surface. Wash down the entire hardboard siding  with water containing mild detergent and allow the siding to dry completely.

Begin painting the siding by applying acrylic latex primer. Apply 2 layers of acrylic latex primer using a paintbrush. Start painting from the upper portion of the siding and work your down so as to minimize paint splatters. Allow adequate drying time for each coat of paint. Finish the paint job by applying a top coat.