Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation
The 2011 Solar Decathlon held in Washington, DC in October featured homes designed and constructed by architecture and engineering students from universities worldwide that employ sustainable building solutions and powered by solar energy.
To my surprise, several of the designs, including Team Massachusetts, whom we partnered with, chose to include rainscreen technology in their designs. (Pictured is the fiber cement siding that was cut to accommodate the screen system designed by Team Massachusetts.
Rainscreens are a system which assumes that water will get beyond the outer surface to underlying layers and be managed and evacuated from the building.
It is not a barrier system – it is a water management system and they are great!
However, the market share in terms of the number of applications in the U.S. of rainscreen technology, the last time I checked, was approximately 10 percent. It is not a large part of the market but we are very familiar with versions of the rainscreen in our every day lives. The brick cavity wall – the space behind the brick that drains the water out is a version of the rainscreen. This is the technique the students utilized with the siding.
Another example is the open rainscreen where panels are suspended off the building with clear passage around the panel. There are no caulk joints, there’s nothing tight, you can see the underlying layers around the panels.
Rainscreen technology ranges from a drained assembly – to a drain and vented assembly – to a pressure equalized rainscreen which uses compartmentalization to prevent excessive positive or negative pressures from developing due to building orientation and exposure to wind and other elements.
This is an extremely durable system because the outer surface of the building repels the majority of the incident rain, deals with the majority of the solar radiation issues like ultra violet light and weathering. It protects the underlying waterproofing and working layers of the building and enables them to hold up longer.
Rainscreens are great systems which are easier for a building owner because they are much easier to maintain. Perhaps the increased use of these systems in competitions like the Solar Decathlon will take hold as we continue to adopt new technologies for building assemblies.