Fiber cement board is a relatively new product that is used to make fiber cement siding. Fiber cement siding is very energy-efficient and as an added bonus it looks a lot like wood. It takes on the look of wood grain while remaining very durable. The downside of using fiber cement siding is that it hates water. Think of what happens when drywall gets wet. A similar end result will happen with the fiber cement siding unless it is properly sealed before it is installed on the home. Painting the fiber cement siding is one way to seal it against water and is also the easiest and least expensive. Painting fiber cement siding is a detailed process and this article will show you how to do it properly.
Step 1 - Clean the Fiber Cement Siding
In order to properly seal the fiber cement siding it needs to be completely free of dust and debris. If there's material left on the fiber cement siding it can cause voids in the painting which gives an access point for water. Place the fiber cement siding on top of the sawhorses and brush away with a broom. Follow up with a tack cloth and be certain that you also clean the edges of the fiber cement siding. Flip the material over and repeat the process.
Step 2 - Priming the Fiber Cement Siding
Use a high quality brand of exterior primer and stir it well. With the fiber cement siding still on the sawhorses; apply the primer. Apply it in even and uniform strokes but do so quickly to avoid dust and debris from settling on the primer. Wait for this layer of primer to dry and then carefully flip the fiber cement siding over. Apply the primer to the back of the fiber cement siding as well as all of the edges. You do not want any water to penetrate the fiber cement siding. It is up to you if you wish to add a second coating of primer.
Step 3 - Install the Fiber Cement Siding
Place a 1 1/2-inch piece of fiber cement siding along the bottom of the wall as a spacer. Start at one side of the wall and put the top edge of the siding on the lowest chalk line and nail in place. Nail only to studs and leaving an inch space at the top of the siding. Do not nail the bottom. Place a piece of plastic behind the joint and on top of the siding. Continue placing courses of fiber cement siding until finished then caulk the joints at the corner.
Step 4 - Painting the Fiber Cement Siding
Use a roller, sprayer or brush to apply the exterior paint to the fiber cement siding. Begin at one corner and work outward. When you see running paint quickly smooth it out. Cover the nails and seams. Allow the top coat to dry completely (according to manufacturer) then apply a second coat.