Pull on your sterile gloves, adjust your respirator, and take cover behind your legal counsel. It's time to do battle with the building industry's equivalent of the black plague... By Matthew Power

Hard-wire fans

By putting your bathroom and kitchen ventilation fans on a single switch (i.e., the same switch as the main light), you guarantee that any time those rooms are used, moisture will be drawn outside. Use a more expensive, ultra quiet fan and don't run it into the attic (an idiotic but common practice). If the homeowner disconnects the fan and gets a moisture problem later on, you have covered your assets. Attach an automatic "on" switch to any whole-house fan, so it comes on and discharges moisture when the indoor humidity exceeds 70 percent.

Isolate add-ons

Where wood decks or concrete patios are attached to the home, a peel and stick waterproof membrane should be applied to prevent water from wicking into wooden sill plates. Concrete patios should slope away and should not be the same height as the interior floor--make patios lower.

Seal ducts

Leaking ducts can misdirect as much as 30 percent of conditioned air. That moisture-laden air can end up in wall and ceiling cavities or attic space. Clean and seal ducts with an approved tape. For even more confidence, follow the advice of Building Science Corp., and confine ducts to those areas where air is conditioned. Improve window detailing

Window flashing must be detailed properly. This is one of the most common and critical subcontractor errors. Housewrap above windows should hang over an adhesive flashing, like Tyvek FlexWrap, at the top of the window, not behind it. Window jambs should include weep holes that direct water to the exterior of the building. Windows with an NFRC U factor rating of .4 or less (typically low-E glazings) will help control condensation. Insulate plates

Radiography shows that the majority of exterior air infiltration in new homes happens down low, at the sill plate, or up high, at the top plate. These cold surfaces provide an ideal place for condensation to occur--thus the common discovery of black mold at the base of studs. To solve the problem, apply high-quality sill gaskets and follow housewrap specifications. Test your next model with a rented infrared scanner. Waterproof perimeter

Despite the best intentions, assume that water will eventually come in contact with the home's foundation. Waterproofing concrete should be considered a mandatory line of defense against mold-causing moisture. Traditional asphalt coatings may last only five years. Instead, look for polymer-enhanced products with expansion and contraction durability, such as Koch Waterproofing's "Tuff-N-Dri" system, or a commercial-grade coating system with a built-in drainage plane. Fortify lumber

As the last line of defense against mold, insects, and dry rot, treating framing lumber makes sense. You have several options: 1. Ask your lumber supplier to pretreat the wood with a "sapstain" product at the mill; 2. Use a product like LP's "SmartGuard" family of pretreated materials; 3. Request delivery of lumber that is properly "stickered," meaning the pallet of lumber is separated with tiny sticks, allowing air to flow through, which prevents mold; or 4. Treat the lumber on site with a borate-based product. Wick your brick

Extra mortar spilled behind brick veneer walls has caused many a moisture woe because the mortar can block weep holes. Weep holes should be left every 32 inches in brick walls. To cover all bases, clever masons will install a piece of rope that runs behind the brick and out through a weep hole at the base of the wall. That way, if debris or mortar blocks drainage, the rope serves as a channel; when it rots away, water still has a path to follow. Back to MOLD