Elevated on four-foot piers, the Green Dream 2
“wash and wear” house has water-tolerant construction
details that would allow it to survive deep water inundation with
little need for repair or replacement of materials.
In the aftermath of Hurricane Katrina, Louisiana State
University professor Claudette Reichel, who chairs LSU's "LaHouse"
building demonstration project, invited building scientist Joe
Lstiburek down to Louisiana to look at the damage and to offer
advice on the reconstruction problem. After some study, Lstiburek
proposed a set of construction details tailored to the conditions
of a region like the low-lying Mississippi Delta. The idea was to
build in a way that allowed a house to withstand being inundated
briefly with floodwater — and allowed homeowners to quickly
clean, flush, and repair their homes and put the buildings back
Coastal Contractor covered Lstiburek's recommendations in July
of 2006 (see "Low Country
Rx: Wet Floodproofing," by Ted Cushman, Coastal Contractor
7/06). Now, LSU has moved beyond theoretical prescriptions,
building two demonstration houses based on the new principles.
Claudette Reichel calls the concept the "Wash and Wear House."
The two homes have flushable, drainable wall and floor
assemblies that are based on the same concept, but have different
details. The first house (called "Green Dream
1"), with a HERS rating of 64, has high-density spray foam
within the wall cavities, applied at less than full stud depth to
allow a drainable space under the wallboard. The second home
Dream 2"), still under construction, uses exterior-applied
rigid foam insulation, leaving the wall framing cavities completely
empty. Both homes use DensArmor Plus drywall, a paperless
gypsum-board product from Georgia-Pacific that has a fiberglass
mesh face and moisture-resistant core.
Rigid foil-faced insulation applied to the
outside of the Green Dream 2 house leaves interior stud cavities
void, able to be drained, rinsed, and dried in case of
Underfloor insulation details also vary. Green Dream 1 has
sealed rigid foamboard fastened underneath the floor joists, while
Green Dream 2 has high-density spray foam applied to the underside
of the floor sheathing.
Treated-wood floor framing and spray-applied
foam insulation make for a water-resistant, easily washable
The point is the same in each case, however, explains Reichel:
"We're combining high energy performance with hazard survivability.
So after a similar event to the one that destroyed their previous
home, the house would not only survive, but be very easily
cleanable and restorable, with very little need for replacement of
anything. You open a gap at the top and the bottom, flush it out,
drain it, and ventilate it." High-performance windows, good
air-sealing, and advanced hvac mean the homes perform better day to
day, says Reichel — "and if another Katrina happened, as soon
as people are allowed back in the city, those folks can clean up
and move in. They don't have to wait for drywall, don't have to
wait for insulation, don't have to wait for contractors -- it's
just wash and wear."
More Green Dream 2 construction photos are available at the
Green Dream 2 blog.
We'll take a closer look at the Green Dream houses'
energy-efficient hvac systems, hurricane-resistant insulated roof
structures, and termite-resistant framing in upcoming issues of