When Contractors Fail to Understand the Dynamics of Building Science, the results can mean long term headaches for unsuspecting home owners. Consider this bathroom vent thru a flat roof on a DC home renovated and put on sale for over $1M.
Seems rather innocent to the untrained. However, the contractor has failed to consider the fact that this is intended to exhaust warm humid air from a bathroom. When this metal pipe is exposed to warm humid air on the inside, during freezing winter temperatures or 2 feet of snow, the inevitable condensation occurs. That condensation will flow back to the exhaust fan, ruin the fan, possibly cause an electrical short and damage the interior ceiling. The buyer thinking, ‘oh I need a new fan’, will replace the fan never thinking the cause has to do with the contractors bad decision to run a metal exhaust to the roof.
Unfortunately trade schools that used to teach this stuff no longer exist. It is very easy to become a “licensed contractor” in most states with little to no knowledge of building science. Far too often, we here, “the work was done by a licensed contractor” as the justification or proof that the work was done correctly.