Mold inspection and testing in Shiloh, PA

Shiloh isn't a borough — it's a census place inside West Manchester Township, spread along the Route 30 corridor west of the city. That matters for one practical reason: the housing stock is suburban and relatively young. Most of what I inspect here was built between the early 1960s and the late 1990s, on poured or block foundations, in subdivisions laid out on old farmland. There is very little stone, very little shared masonry and very few dirt cellars. What there is instead is a lot of houses built tight enough to hold humidity and vented badly enough to keep it.

The split-level is the signature problem. In a split or bi-level, the lower level is cut into the grade so that one or two walls are in contact with soil while the rest of the house stands above it. Soil temperature at that depth stays in the fifties most of the year. Room air in July is in the seventies and carrying a lot of moisture. Put humid air against a cool wall and you get condensation — on the block, behind the drywall, under the carpet pad, inside the closet on the buried side. Homeowners tell me there's no leak, and they're right. There doesn't need to be one. I find this in Shiloh houses more than any other single mechanism, and it reads clearly on a meter and a thermal camera once you know to look for the temperature difference rather than a water stain.

The second pattern is upstairs, in the attic. Ranchers and splits of this era were built with modest ventilation, and then at some point in the last few decades somebody added insulation over the attic floor, which reduces airflow further, and installed or replaced a bath fan. In house after house that fan terminates in the attic, in a soffit, or in a joist bay instead of outside the building. Every shower sends warm wet air into a cold space. In January you get frost on the nail heads and the underside of the sheathing; in the first thaw it melts into the insulation and the framing. After enough winters, the sheathing carries a dark band along the nail lines, and that is what people photograph and send me.

The third is mechanical, and it's the one people least expect. When the original air conditioner gets replaced, it very often gets replaced with a bigger one, on the theory that bigger is better. It isn't. An oversized system drives the thermostat to setpoint quickly and shuts off before the coil has run long enough to condense water out of the air. You end up with a house that's cold and humid simultaneously, which grows mold on exterior-wall closets, behind furniture and on north-facing corners. I take humidity readings room by room, and the pattern is usually obvious once it's written down.

Underneath all that, the ordinary things still happen: a sump pump that quit on a finished basement, thirty years of settled backfill that now pitches toward the house, downspout extensions pulled out when landscaping went in, a slow roof leak in a flat-roofed commercial unit along Route 30 that traveled twenty feet down a beam before anybody saw a stain.

The value of the inspection here is diagnostic rather than dramatic. I measure moisture, temperature and humidity, image the surfaces you can't see behind, and send samples to an independent accredited lab. Then the report tells you whether you're calling a roofer, an HVAC contractor, a waterproofer or nobody at all.