Wall Cladding
Summary
Wall cladding is the outer layer of an exterior wall that sheds weather and sets the building's appearance, attached over a water-resistive barrier and often a drained cavity. Choose cladding by how it handles water, not only by look: decide whether it is a barrier, a drained system, or a rainscreen before detailing joints and attachment.
Cols
Terminology
- Rainscreen: cladding separated from the wall by a cavity that drains and dries
- Drained and back-ventilated (D/BV): rainscreen with openings at the top and bottom of the cavity; not watertight, it drains most water and dries the rest
- Pressure-equalized (PE): rainscreen with compartmented cavities that limit wind pressure driving water through joints
- Water-resistive barrier (WRB): layer behind the cladding that drains water that gets past it
- Cladding attachment: furring, clips, or fasteners that hold the cladding to the wall
- Barrier cladding: cladding that relies on its own joints and sealants to keep water out
Types
- Fiber cement, wood, and metal: boards, panels, and shingles
- Masonry veneer: brick and stone; not a true rainscreen unless ventilated
- Terra cotta, GFRC, fiberglass, and concrete panels: rainscreen panel options
- Stucco and EIFS: applied finishes over lath or insulation board
- Vinyl and aluminum siding: lightweight lap siding
Selection
- Pick barrier, drained, or rainscreen type from climate, exposure, and building height
- One source advises against vented-only rainscreens above about four stories because of condensation; sources differ, so check current guidance
- Rainscreens need coordinated detailing and can cost more than other options
- Check fire behavior of combustible claddings and insulation under the parent code reference
Detailing
- Provide openings at the top and bottom of every drained cavity
- Keep an overhang or cap above the cladding where the system is not watertight
- Lap the WRB and flash windows, doors, and penetrations
- Support the cladding on solid backing; attach through insulation with rated fasteners or clips
- Allow for thermal and moisture movement at joints
Uses
Specific uses
- Houses and low-rise buildings
- Commercial and institutional facades
- Rainscreens on mid-rise buildings
Pros and cons
Pros
- Wide range of looks and materials
- Rainscreens drain and dry the wall behind the cladding
Cons
- Rainscreen detailing needs more design coordination
- Combustible cladding and insulation trigger fire tests
- Joints and flashing are the usual leak points
Manufacturing and cost
Construction
- Cladding is fixed to furring, clips, or sheathing over the WRB, with joints, trim, and flashing set at each edge
Main manufacturers and suppliers
Trade association: Metal Construction Association.
Sources
- Construction Specifier: the two types of rainscreen wall system design, https://www.constructionspecifier.com/the-two-types-of-rainscreen-wall-system-design/
- Metal Construction Association: understanding rain screen wall systems, https://metalconstruction.org/view/download.php/online-education/education-materials/walls-educational-files/materials/understanding-rain-screen-wall-systems
- RDH Building Science: rainscreens, when, where and why, https://www.rdh.com/wp-content/uploads/2022/12/Rainscreens-When-Where-and-Why_2022-02-16.pdf
- Walls & Ceilings: basics of bulk water management through rainscreens, https://www.wconline.com/blogs/14-walls-ceilings-blog/post/89594-basics-of-bulk-water-management-through-rainscreens
- Facilitiesnet: use cases for rainscreen systems, https://www.facilitiesnet.com/windowsexteriorwalls/tip/What-are-the-Use-Cases-for-Rainscreen-Systems--54017