April 2005

Hurricane-Caused Leaking Walls Lead to New Research Effort

For the past 15 years, researchers at FSEC and in UCF's Industrial Engineering & Management Systems department have worked together on a wide variety of research projects as part of the U.S. Department of Energy-funded Building America and its predecessor program.

However, last summer's hurricanes created a new problem for Florida homeowners that opened the door to an interesting new study just getting underway.

Spray rack testing
FSEC's Neil Moyer (standing, left) and and Mike Mullens from the College of Engineering discuss the operation of the spray rack that simulates hurricane water conditions while two UCF students (left) make adjustments to the pumping equipment.
(Photo credit: Nick Waters)

Not long after the hurricanes roared through the state, thousands of homeowners started complaining about water leaking through their walls. FSEC's Subrato Chandra and Neil Moyer met with the College of Engineering's Mike Mullens and Bob Hoekstra to discuss this phenomenon, since such problems hadn't been reported in Florida homes before. What they found suggested the need for some important new research to deal with the effects of hurricanes.

"When you look at the major hurricanes that have hit our state in the past," Chandra said, "what we've often seen is that damage has been extensive and buildings have been totally destroyed. Last summer, though, the new homes stood standing but experienced significant water leaks through seemingly intact walls to the inside of the homes-damaging carpets, baseboards and creating mold problems."

The FSEC/UCF College of Engineering research team realizes the importance of understanding the "leakiness performance" of walls as the first step in helping homebuilders avoid this problem in future buildings. "The American Society for Testing and Materials (ASTM) has a procedure for measuring the water absorptance of walls under wind-driven conditions," Chandra explained. "This gave us the first step in setting up a research effort to help us better understand this problem, so we batted around a lot of ideas on what to do."

Mullens came up with the idea of building a box to ASTM standards that could be screwed onto an outside wall. The box has a spray rack which sprays water directly onto the wall. It can be pressurized to simulate wind conditions as high as those reaching hurricane strength.

Spray rack mounted on test lab

The spray rack attached to the windows is used to simulate conditions up to hurricane strength.
(Photo credit: Nick Waters)

They've tried it out on a couple of buildings, and recently brought it to FSEC to test it on the center's Building Science Laboratory. After four hours of thoroughly soaking the walls, the team found that water was absorbed by the walls but did not leak through into the building's interior.

"What we're thinking," Chandra said, "is that walls have a certain capacity to absorb and desorb moisture. Under typical conditions such as rain, there is enough capacity to hold the water in the walls until the sun dries it out, keeping it out of the building. Hurricanes are just too much for the average wall, though, and the water gets through the wall to the inside of the building."

Based on results so far, the researchers plan to continue their experiments. They're going to be meeting with homebuilders in Central Florida to recruit builders willing to let them test nearly-completed homes.

Chandra pointed out that builders need to be aware of the possibility of more major hurricane-like storms that can create problems they haven't seen before. He noted that "the nature of last year's hurricanes left us with a huge problem of water leaking into homes. Because most buildings were still standing after the storms, we became acutely aware of this problem and realized its importance. Builders need to find out what causes this problem and how to fix it, so we're going to be working closely with them, the Florida Building Code Commission and other building scientists to determine the nature of the problem and to help figure out solutions."