Replace Water Damaged Siding With Fiber Cement Siding

Replace water-damaged siding with fiber-cement siding

I’ve had plenty of phone calls over the years from homeowners who are convinced they have to reside their entire house because some of their siding has been damaged by water. Yet when we take a look at these jobs, we often find that relatively little siding has to be replaced. Even better, the homeowners are surprised to learn that the fiber cement siding we use as a replacement is often a perfect match for what they have. What’s more, it resists damage from water and insects.

What causes water damage? We get significant rainfall along the Gulf Coast where I live, and that leads to a lot of siding problems. But even in dryer parts of the country, lawn sprinklers that routinely wet siding or shrubs growing too close to the house to allow sufficient air circulation also lead to damaged siding.

Most of the problems we see involve hardboard siding because it is so common, and it’s not always installed correctly. Carpenters might have overdriven the nails, improperly sealed joints, or allowed cut edges to come too close to the ground. Over time, rain runoff soaks into the siding and causes mildew and rot. By the time the homeowners notice the siding is soft, they’ve got a real problem on their hands.

Replacing bottom boards with fiber cement siding.

The good news is that damage is usually limited to two areas: the first three courses of siding (2 ft. or so up from the ground), and wood-framed chimneys, or chases, that aren’t protected by a roof overhang. Where the siding has been installed properly, and where it’s not soaked by rain, it’s usually fine.

We tear off the damaged hardboard and replace it with fiber-cement siding. The sheathing and framing sometimes need repairs too, but that is less common. In most cases, the original layer of building paper or housewrap at the bottom of the wall was enough to prevent water infiltration and damage beneath the siding.

The wood-grain pattern on the fiber-cement siding is often a perfect match with existing hardboard, although it’s not as good a match with real rough-sawn wood. When the new siding has been painted—two coats of top-quality acrylic latex over a primer—the repair is hard to spot. Another plus is that fiber cement can be brought closer to the ground than the 8″ minimum for hardboard.

Siding after replacement with fiber cement.Several brands of fiber cement siding are available; we’re most familiar with HardiPlank from James Hardie Building Products. The siding is made from portland cement, sand, cellulose, and other additives and is available with smooth or simulated wood-grain finishes.

Planks are 12 ft. long x 5/16″ thick and come in a half dozen widths, which means weather exposures can vary from 4″ to 10¾”.

Though it used to be a little more expensive than hardboard siding, fiber cement siding now costs less in many areas. Hardboard siding that’s 8″ wide costs 45 cents per linear foot, while fiber cement runs 37 cents.

There’s one more thing homeowners like about fiber cement siding—it holds paint better than wood. One house I worked on still looks great after eight years. Around here, most people start thinking about repainting after only three or four years.

Further Information


  1. Thanks for the information. My aged fiber cement siding is popping out in some area, so I plan on nailing it back in in other spaces by a studs, but what do I fill old nail holes with? and can I caulk that edge of the vertical popped siding too?
    Also, it seems that when siding was installed years ago, they added a two inch strip on the bottom of it behind the trim board wand that strip has now rotted because of water damage. I plan on replacing it but what do I do about that bottom 2″ of torn building paper?

  2. There is water damage on our garage siding near the ground as described in your article. How do you get under the row of siding above the damage to replace the bad row?

  3. I cannot find cement siding that will match the siding on my home. I desperately need to repair the damaged siding, but I cannot afford to replace all of the siding simply because I cannot find a matching style. I’ve already spent several thousand dollars to replace carpet and floor when rain found it’s way in from the patio through the damaged siding. The original siding is the look of three 4″ wide boards on each 12″ siding section. Is there a brand that carries this look in cement fiber siding?


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