How to Repair Fiber Cement Siding

Lead Image for How to Repair Fiber Cement Siding
  • 2-4 hours
  • Beginner
  • 30-60
What You'll Need
Power washer
Wire brush
Diswashing detergent
Acrylic paint
Work gloves

Fiber cement siding looks like wood, but it’s actually a tough, industrial-material alternative that’s waterproof, fire-proof insect-resistant, making it a very popular choice for most homeowners. However, even this stuff isn’t impervious to the test of time and the forces of nature, so you might find yourself needing to give your siding a little sprucing and repair from time to time. Fortunately, most jobs you should be able to easily take care of yourself, with a minimum of time but a lot of elbow grease. If there’s been significant damage following a severe fire or some other accident, however, then the siding may need to be replaced. Otherwise, keep reading for some tips on repairing fiber cement siding.

Step 1 – Clean the Siding

Before you do anything else, you want to get the siding nice and clean. Not only will that automatically improve its appearance, but it will prepare the surface of the siding for any further repairs that you might undertake in the coming steps. To clean it, start by taking a light wire brush and dipping it in a buck of water mixed with a cup of bleach and some dishwashing detergent. Scrub away at any bits of mold, mildew or stains (keep in mind that tough, persistent stains might just have to be painted over).

Then, mix some water with a little trisodium phosphate and hook up your power washer. Spray away the rest of the dirt and grime from the siding. Then refresh the power washer with fresh water to give it a good rinse.

Step 2 – Replace the Caulking

Over time, caulking around windows, door frames and trim can crumble away and fall out. Use your caulk gun to replace all caulking now.

Step 3 – Repair any Holes

If you have some small cracks and holes in your siding, you can fill them in with patching material specifically designed for this purpose, available at your local hardware store. Keep in mind that the patching will be obvious, whether or not you paint over it, so this is the best solution if the cracks and holes are in out of the way places that aren’t readily noticeable. If you have really big holes and cracks, then the siding will probably have to be replaced altogether.

Step 4 – Apply Fresh Paint

Finally, now that your siding is clean and renewed, it’s ready to paint. Make sure that the siding is completely dry from the washing, and that the caulk and patches are dry too. Use only completely acrylic paint, and apply with rollers. Depending on the size of your house, you may need a ladder to reach the area of siding near the roof. Remember, above all else, that you must not stain siding; the material is not able to hold the stain, and the end result will not be pretty! Only use paint.