by Jeffrey C. May —
I’ve inspected dozens of newly constructed homes or additions, as well as spaces that were just renovated, and they were full of IAQ problems. Many of these problems started to occur during construction or renovation. In this article, I’m going to focus on mechanical systems. In the next article, I will discuss IAQ problems in basements in new construction.
Photo above: Leaky duct boot -May Indoor Air Investigations LLC
Ducts
Dirty ducts: I’ve found an amazing collection of debris in ducts in new homes, including coffee cups, tape, a tape measure, strip flooring, clumps of grout, fiberglass, and even a donut inside a paper bag.
One man was even about to move out of his house because of a horrible smell coming from a bedroom supply. Someone had spilled coffee inside the duct, and the cream had gone sour at an elbow in the basement.
In another new home, the ducts were in place but the contractor had not installed the filter in the air handler for fear that the expensive (but disposable) filter would get soiled. What is a filter for, I wondered; the ducts and the air handler were full of sawdust and drywall dust. The builder had to pay for an expensive system cleanup.
In a third home that was still under construction, sections of rectangular ducts were sitting upright on the basement floor. Workers were sawing wood in the basement, and the ducts were already filled with biodegradable sawdust.
I always recommend that workers saw wood outside the house. If weather requires them to saw inside the house, some sort of exhaust system should be in place to filter the sawdust. Sawdust on foundation walls and in ceiling fiberglass inevitably becomes moldy, so insulation should be installed and foundation walls HEPA vacuumed after all basement sawing is done.
Most of such material inside ducts is biodegradable. If the relative humidity is high enough, mold will grow: a certainty if the sawdust ends up on a cooling coil. Then the system will carry byproducts of this growth into habitable spaces.
Duct boots: These should be airtight to prevent musty basement or crawl space air from flowing up into the room above.
Read the full article in the February digital edition of Healthy Indoors Magazine at: https://hi.healthyindoors.com/i/1088111-hi-feb-2019/35
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