Fiber Cement & Cedar Siding Moisture Management

Fiber Cement & Cedar Siding Moisture Management

The durability, superior appearance, and added value of fiber cement siding makes it a popular choice of builders and designers. The leading manufacturers recognize that fiber cement siding lasts longer and resists moisture problems when installed over a predictable, rigid rainscreen air gap.

Natural cedar siding’s unique durability, natural aging and warm aesthetic have been recognized for centuries. While cedar’s appeal is unchanging, the rest of the wall assembly has changed drastically with the introduction of plastic WRBs, air sealing and increased insulation that have altered the walls ability to dry out. Naturally occurring surfactants in real wood siding compromise the water repellency of many WRBs, allowing incidental water to become entrapped in the wall system without the ability to dry out, leading to damage to the sheathing and wall components.

Best practice detailing for fiber cement & wood siding

  • Rainscreen drainage gap that won’t compress
  • Ventilation at horizontal terminations to allow the wall to drain and dry

Essential Moisture Management Components

Sure Cavity Rainscreen Drainage Plane

Ventilated Rainscreen Air Gap

An air gap prevents hydrostatic pressure in the wall assembly, lets gravity drain liquid moisture, and water vapor to exit at ventilated terminations. Sure Cavity™ features rigid channels and a built-in bug screen for a clear and predictable drainage gap along the entire backup wall. Sure Cavity lays flat on the sheathing and reduces nail drive-through for easier installation and superior appearance.

Sure Cavity 

Corrugated Lath Strip with Siding

Rainscreen Strips

An air gap prevents hydrostatic pressure in the wall assembly, lets gravity drain liquid moisture, and water vapor to exit at ventilated terminations. Lightweight Corrugated Lath Strip™ creates a rainscreen air gap in both horizontal and vertical siding applications. 

  Corrugated Lath Strip

Rainscreen-compatible termination

Vented Rainscreen Terminations

That water that drains to the bottom of the wall needs an exit strategy. MTI Vented Edge Metal™ is a metal termination designed for the Sure Cavity™ rainscreen.  With frequent holes for drainage and ventilation, MTI Vented Edge Metal enables the rainscreen wall to dry to its fullest potential.

MTI Vented Edge Metal 

Moisture Diverter on Drainage Plane

Moisture Diverter Above Openings

Window rough openings are a common weak spot for moisture problems - but if the rough opening doesn't get wet problems are prevented. The Moisture Diverter™ channels water in the rainscreen drainage plane away from the rough opening to reduce the potential for leaks and keep windows dry. 

Moisture Diverter

Ordering & Expertise

 1-800-879-3348 or  Contact Us