Fiber Cement Siding Over Rainscreen

Rainscreen or wall cavity siding systems are growing in popularity in areas that see a lot of moisture and wet weather. The system allows for air flow and moisture release between the siding and the building itself, rather than having the siding applied right up against the structure. This in turn keeps the building drier and helps prevent the growth of mold and the onset of wood rot. Fiber cement siding can be easily installed in a rainscreen system by attaching the siding over non-structural furring strips. This allows you to get the benefits of the system and the benefits of using attractive and durable fiber cement siding at the same time.

How the System Works

In order to be effective, a rainscreen needs to consist of a weather barrier on the building’s exterior, followed by a cavity or air space that is then covered with the siding. Air can flow through the cavity, creating equal pressure through the entire area, and allowing rain and moisture to drain out and away, rather than collecting where it may do damage to the building.

Because it is estimated that more than 50% of homes have some degree of mold problem due to trapped moisture, rainscreen systems can be beneficial in helping to dry out trapped moisture in a timely way. Areas that don’t see a lot of sunlight, or that get a lot of rain with the result of trapped moisture and water behind the siding can benefit from having a rainscreen system installed along with new siding.

A rainscreen is only as good as its design and installation, however, so when constructing one using fiber cement siding, it’s important to adhere to guidelines set up by the manufacturer of the product, state and local building codes, and rainscreen windload recommendations to ensure success.

Installing Fiber Cement Siding Over Rainscreen

To install the fiber cement siding over a rainscreen, furring strips need to be applied to the building’s exterior over the weather barrier. These furring strips or lathe are necessary to give the fiber cement something to adhere to.

The furring strips need to be aligned vertically every 24-inches at the framing member locations to provide the proper support. It’s important that the strips be attached at these locations in order to ensure that the fiber cement will not warp or crack over time due to inadequate support.

Because the fiber cement will need to be attached not only to the furring strips, but through them to the structure, you’ll need to ensure that the fasteners are of sufficient length based on each individual project. Keep in mind that the total thickness of the furring strips, the exterior cladding, and the insulated sheathing between the framing members should not exceed 1-inch in thickness. Always check with local regulations to find out the requirements for the thickness of the furring strips or lathe before beginning.

If you are installing fiber cement shakes on the building, you may also need to install horizontal furring strips as well. Because solid furring strips are not recommended for this application, check with Trimline to find drainable options for this purpose.

Be sure to adhere to the latest fastener, flashing, and sealing requirements for the fiber cement product that you are installing in order to get the best results.

Considerations for Installing Fiber Cement Over Rainscreen

Like any type of installation, installing fiber cement in this manner is subject to all state and local building codes. Always follow local regulations and check with the local governing offices to find out the exact codes for your area. Allura fiber cement products do not require an air gap to be covered under warranty, unless local codes dictate its use.

In order for the fiber cement products to be covered under warranty, they must be installed according to the installation requirements outlined in the Allura Fiber Cement Siding Installation Manual. This is the case whether installing the material over a rainscreen or not.

The rainscreen itself should be installed to ensure that the local windload and anchoring requirements for the system and the fiber cement are met. Always double check the latest reports on fastening requirements for guidance.

Allura is not responsible nor liable for the rainscreen system, its installation, or its performance.

Combine Fiber Cement and Rainscreens

Fiber cement siding is one of the best investments out there for home exteriors. Combined with a rainscreen, fiber cement siding or panels can offer protection against nearly anything the elements can throw at it, while still offering attractive style and curb appeal at the same time. Begin combining fiber cement siding with rainscreens on homes in wet areas to get the best possible protection and the most durability and style available for any home you work on or own.