Mystery Inspector visits a Meritage Homes job site near Phoenix where good water management and air barrier details are discovered.

Assisting with this inspection is Peter Yost, vice president of Technical Services for Building Green in Brattleboro, Vt.

Houses in the desert can still have water problems
Pete tells Dan that even in the desert, houses can rot. Houses that rot are bad for business; they are also bad for families. The two main problem areas are exterior sprinkler heads that inadvertently soak floor slabs and walls from the outside, and shower heads that soak poorly detailed floors and walls inside showers.

The shower in this house has fiberglass-faced drywall, such as Densshield or GreenGlass, which is much better than typical 'greenboard' or 'moisture-resistant' drywall. If the drywall is covered with some sort of a membrane, such as Schluter's Ditra membrane, or a spray-on membrane such as C-Cure Pro-Red or RedGard, all the better.

High-performance in desert means beating the heat 
Pete and Dan concentrate on the basics: stopping heat flow and air leaks through the building shell. The weak links in an insulated wall are windows and 'thermal bridging' through the framing, so they offer good opportunities for improvement. An air-tight shell helps the mechanical system deliver a comfortable, healthy, and energy-efficient house.

(Too bad the Mystery Inspectors neglect to check the specs on the window stickers!) Better windows and insulation can mean smaller AC systems, so the cost approaches a wash.

This house is wrapped with exterior foam sheathing (1-inch expanded polystyrene, or EPS), providing a continuous boundary which all but eliminates thermal bridging. Most of the OSB wall sheathing was eliminated in favor of foam, though the corners and other critical locations have 1/2-inch OSB sheer panels covered with 1/2-inch XPS.

Replacing the OSB sheathing in favor of foam sheathing delivers a better house at about the same cost.

The air barrier in this roof/wall assembly is found right where you want to find it: both inside and outside. Inside, spray foam fills the stud and rafter cavities; outside, stucco provides the continuous air barrier.

Drip irrigation is an efficient watering system
Before awarding the folks at Meritage Homes an attaboy, Pete and Dan check in on a finished home to peek at the sprinkler heads. Sure enough, drip irrigation—delivering just enough water right to the thing that needs it: the plant.

Dan awards an attaboy, and Pete says that Meritage Homes is "not watering down its high performance."

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Other Mystery Inspector Jobsites:
Arlington, Virginia