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Mold Testing in South of Broad, Charleston
A mold test below Broad Street reads a house that stands on made ground. Water Street was Vanderhorst Creek before anyone paved it. The seawall drive along Murray Boulevard was laid on fill against the Ashley, looking across at West Ashley. The single houses here turn a narrow end to the street with tiered piazzas facing the southwest breeze. They sit on raised brick piers over half-sunk ground floors that clear the water table by very little.
So the damp arrives from below and from the street rather than from a cellar, because there is no cellar down here to pump out. Cool masonry holds harbor air against old lime plaster, heart-pine baseboards and the backs of wood paneling for most of the year. Those materials take water in slowly and let it go slower.
King tides are the other half of it. On the highest of them the harbor pushes back up through the storm drains and stands on South Battery, on Water Street and on the low blocks toward East Bay. The street clears when the tide turns. What went into the pier bases and the sills does not.
Our part in this is small and worth stating plainly: we do not open a cassette or meter a sill. We hand your details to independent samplers working the lower peninsula. The accredited lab that counts the catch invoices you rather than us, so the numbers are yours to argue with.
Where does the water go in a house with no cellar under it?
It goes sideways into the fabric of the house. A tidal push that stands in the street for part of an afternoon wets the pier bases, the sill and the lowest run of plaster. Then the tide drops and the pavement looks dry by evening. The wood does not keep to that schedule. Heart pine that has taken salt water dries at the face first and holds damp deep in the grain. A painted baseboard seals it in. Growth turns up later on the back of that board or inside a closet built against a shared party wall, long after anyone stopped thinking about the tide.
The vented void under a raised ground floor tells the same story in a smaller room. It takes warm harbor air all summer and drops it onto joists that stay cool, so condensation forms where nobody looks. Add one slow drip from an old supply line and the wood never gets a dry stretch. A moisture survey walks that void first, meters the sill and the pier bases and only then decides whether a lab sample would tell you anything you do not already know.
Is that white bloom on the old brick actually mold?
Usually it is salt. Masonry that has taken harbor water pushes salt back out to the face as it dries and leaves a chalky white film that brushes off dry and returns after the next wet spell. Old tide staining plays a similar trick: a brown line left on a baseboard by a flood years ago can look alarming while the material behind it is bone dry and completely inert. The mark is not the question. Whether the wood behind the mark still reads wet is the question. A meter settles that in a minute.
Where the wood does read wet, air sampling starts to earn its cost. The lower peninsula carries spores in the outdoor air every month of the year, so one indoor number on its own settles nothing. A trap runs in the room and a matching trap runs in the garden the same afternoon. The lab counts both genus by genus. What you are paying for is the distance between the two.