Structural drying and dehumidification in Pittsburgh, PA

A wet house dries on its own eventually. The problem is the word eventually. The EPA says wet building materials must dry within 24 to 48 hours to avoid mold growth. Drywall, subfloor, and framing cannot do that by themselves in a closed house. The CDC gives the same window and says to use fans to dry wet areas and to throw away anything you cannot clean or dry quickly.

Here is the trap. Open windows and a box fan move air, but they do not remove water from the building. In a Pittsburgh summer the outside air is often wetter than the air inside. In winter the heat is on and the house is sealed. FEMA's guidance on flooded buildings says natural drying slows a lot in cold or humid conditions. In those conditions, drying equipment is critical before any rebuilding. Western Pennsylvania is cold half the year and humid the other half. That is why the equipment matters here.

Two kinds of dehumidifiers show up on a water job, and they work in different ways.

Refrigerant units are often called LGR, or low grain refrigerant, dehumidifiers. They cool the air so the water vapor in it condenses. A cold glass sweats the same way. The water drips into a pan or pumps out a hose. They are the workhorse for most house losses in warm, humid conditions. Equipment makers note they have an ideal operating temperature range. They lose power in a cold space.

Desiccant units pull moisture from the air by chemical attraction instead of cooling it. Manufacturers point to them for cold or unheated spaces, for winter work, and for dense materials like hardwood, plaster, and concrete. They can also drive the air drier than a refrigerant unit can. That is what pulls the last water out of a thick material.

Which one we set depends on the loss. A finished basement in July with wet carpet and drywall usually gets LGR units. A plaster-and-lath house in January, or a hardwood floor, often gets a desiccant. A big commercial space may get both. The choice is part of the plan, not a guess, and we explain it on site.

Dehumidifiers only dry the air. Air movers are what get the water out of the materials and into the air in the first place. They push a fast sheet of air across wet walls, floors, and framing. That speeds up evaporation at the surface. The dehumidifier then grabs that moisture out of the air before it can settle somewhere else.

The two have to run as a pair. Air movers without enough dehumidification just move water from the floor into the air and onto the windows. Dehumidifiers without air movers dry the room while the wall stays soaked. The EPA notes that raising air circulation and temperature increases the speed of drying. So in winter we often add heat as the third leg.

On a typical job you will see air movers aimed along the wet walls and across the floor. One or more dehumidifiers sit in the middle of the space. The doors stay closed to keep the drying chamber tight. Count on it being loud for a few days. That noise is the sound of the water leaving.

Psychrometrics is the science of moist air. The IICRC lists psychrometry and drying technology as a core part of its water damage standard. You do not need the math. You need three ideas.

• Temperature. Warm air can hold more water than cold air. Warm up the room and the materials give up water faster.
• Relative humidity. How full the air is, as a percentage of what it can hold. The EPA says to keep indoor relative humidity below 60 percent, and ideally between 30 and 50 percent.
• Grains per pound. The actual amount of water in a pound of air. Relative humidity can look fine on a cold morning while the air is still carrying a lot of water. Grains tell the truth.

We read temperature and humidity in the room, outside, and at the dehumidifier outlet. Those numbers tell us whether the equipment is winning. If the grains in the room are not dropping day over day, something is wrong. It may be a hidden wet area, a leaky chamber, or the wrong dehumidifier for the temperature. We fix it that day instead of letting the equipment hum for a week.

Every day a job is running, a technician comes back and reads it. Moisture content in the walls, floors, and framing with pin and pinless meters. Temperature and humidity in the air. Equipment running and placed right. Those readings go in a log with photos. You get a copy. So does your adjuster.

That is not just our habit. It is how the industry standard reads. The ANSI/IICRC S500 is the Standard for Professional Water Damage Restoration. It lays out the procedures and precautions for drying a water loss in homes, businesses, and institutions. It covers the equipment, the psychrometrics, and the project documentation. Our technicians are IICRC certified, and the S500 is the standard they dry to.

What does the log prove? That the materials were wet, that they got dry, and how fast. FEMA's guidance uses a pin meter and a simple scale for wood framing. Readings above 20 percent are wet. The range from 15 to 20 percent is caution. Below 15 percent is dry and ready to rebuild. We dry to the dry standard of the building. That is what the unaffected parts of the house read. We do not pull equipment until the wet areas match it.

Most house losses dry in a few days with the right equipment. Thick materials take longer. Plaster, hardwood, and framing hold water deep. A basement that sat for a week before anyone called takes longer than one we reached the same day. If you want the longer answer, our article on how long a house takes to dry out walks through the variables.

Two things shorten the clock. Calling fast, because materials give up water easiest before they soak through. And proper extraction first, because every gallon the pumps pull out is a gallon the dehumidifiers never have to. Our page on emergency water removal before the drying starts covers that first step. For a basement, the order is pump, strip what cannot be saved, then dry. We cover drying a flooded basement after the pump-out on its own page. Hardwood gets its own treatment on our page about hardwood floor drying with sealed mat systems.

We do not repair the pipe that caused the loss, and we do not rebuild. Pipe repair goes to 1-Tom-Plumber Pittsburgh, our sister company. Rebuild goes to your contractor once our log shows the structure is dry.