Open Joint Rainscreen Siding: A Fusion of Performance and Design

The university and design team liked the look of the siding so much it was added to selected interior walls as well.

Southern New Hampshire University’s (SNHU) Library Learning Commons sits at the heart of the university’s 300-acre campus in Manchester, NH. Completed in 2014, the 50,000 square foot library building was pre-designed in parallel with site selection, building size, and a detailed conceptual budget. The owner, construction manager, and design team worked together to create a signature building to communicate the centrality of academics and position the commons at the crossroads of student experience.

Knowing a stunning exterior face was important, the project’s architectural design team chose to wrap the building in Ipé, a beautiful, durable, sturdy hardwood, and to apply the Ipé siding using an open joint rainscreen construction method. This was relatively new technology at the time. Today, more than a decade later, the building is as impressive as the day it opened, and the Ipé siding has remained beautiful, lustrous, and largely maintenance-free.

Open joint rainscreen systems are modern, high-performance cladding solutions gaining traction in both commercial and residential applications. Unlike traditional cladding systems that form a continuous outer shell, open joint rainscreens leave intentional gaps–open joints–between panels. These gaps allow air to flow behind the cladding, promoting moisture evaporation and pressure equalization.

An open rainscreen siding system does not seal off the exterior wall assembly, but rather deflects weather away from direct driven contact, allowing airflow and nonpressurized water to flow through and around the cladding and to drain away without causing damage.

“Building science is starting to get its arms around this type of technology,” said Wes Robichaud, whose firm, Coastal Forest Products, supplied the Iron Woods Ipé panels for the SNHU project. “Every building wall assembly has small defects that allow water to penetrate. These may be seams, window casings, or utility entry ports. Sealing the outside of the building creates pressure at these sites and that pressure pulls water into the building envelope,” he explains. “If the water is deflected and not under pressure when it reaches the wall surface, it just cascades away and evaporates. The rain screen systems proactively manage water intrusion by design.”

“Open joint rainscreen siding is more a shield than a coat of armor,” Robichaud added. “Because moisture is managed more effectively, the building resists mold, rot and corrosion, and the maintenance cycle of the siding itself is significantly extended.”

SPOTLIGHT ON: IPÉ

SPECIES: Handroanthus spp.

ORIGIN: Central and South America; also farmed commercially

COMMON APPLICATIONS: Outdoor applications, including decking, doors, windows, boat docks, boardwalks and furniture, as well as fine furniture, flooring, turnings, and decorative veneers.

CHARACTERISTICS/APPEARANCE: Heartwood is typically olive-brown, with variations in color from a reddish-brown to a dark blackish brown. Sapwood is yellowish-white and easily distinguished. Grain varies from straight to irregular and sometimes interlocked. Ipé is a difficult wood to work with high cutting resistance during sawing and machining. It planes smoothly with tear out in interlocked areas. Ipé can be difficult to glue properly. Surface preparation prior to gluing is recommended. The same qualities making this wood challenging are also what make it so desired – it’s extremely hard and dense with high durability and shock resistance.

JANKA HARDNESS SCALE: 3,510 lbf

COMMENTS: Ipé is a wood of extremes – extremely dense and durable but as a result is difficult to work. Its incredible hardness and strength make it well suited to exterior decking and siding applications. If left unfinished, graying of the wood will occur, but it can last over 20 years outside without preservatives or additional treatments.

Tour the Edward S. Wolak Library Learning Commons

at Southern New Hampshire University - SNHU

Rainscreen systems provide moisture management and are easier to install, requiring no pre-drilling. Hidden clips fastened to the wall assembly allow rainscreen panels to float at a precise distance from wall surfaces, overhangs, and soffits as part of the building envelope. “The Ipé panels used in the SNHU project were pre-finished with Penofin’s Hardwood Oil,” according to Robichaud, “and the open rainscreen cladding system has lasted for years with merely periodic touch-up oil treatments to refresh the color, replace the shine, and maintain the uniform appearance of the wood.”

In fact, impressed with the beauty of the Ipé wood as the rainscreen siding and sunscreen were being installed on the building’s exterior, the SNHU project design team decided to integrate Ipé into the interior of the learning center itself. “We usually think of tropical hardwoods as exterior decking and boardwalks, but SNHU brought the wood indoors with a look that is strikingly beautiful. Although Ipé does not have knots or other textural accents, it has exceptional vivid color variation. The use of Ipé decorative wall cladding accents throughout the learning center has brought the warmth and beauty of the natural wood exterior into the very heart of the university,” Robichaud said.

For builders, architects, and designers aiming for long-term durability and visual impact, open joint rainscreen systems are a compelling choice. These systems protect the building envelope while offering a sleek, modern aesthetic that is popular in contemporary architecture for both minimalist and high-design projects. The crisp engineered look of the open joints gives buildings a visual rhythm and a refined, intentional appearance, with clean lines and an alluring sense of depth and shadow.

“We have used the SNHU library project as a model to attract other projects and to demonstrate the many benefits of the open joint rainscreen construction methodology,” Robichaud said. “The success and enduring beauty of the SNHU Library Learning Commons has opened the door for numerous other projects, and architects and designers are embracing the concept. As it gains acceptance and becomes better understood, we expect to see more uptake in the future.”