BATHROOM EXHAUST FANS – IS YOURS DOING THE JOB?

A BATHROOM EXHAUST FAN – WHAT IT DOES

Bathroom activities such as bathing and showering can add a considerable amount of moisture vapor into the bathroom. Without sufficient ventilation, moisture vapors can condense on surfaces and lead to mold problems, drywall damage, damage to wood including baseboards, cabinets, and more.

A bath fan provides air ventilation. A properly sized bathroom fan removes the moisture and helps to eliminate odors and fumes from cleaning agents.

PROPER BATHROOM VENTILATION

There are two primary considerations for installing a bathroom exhaust fan that functions properly.

  • Proper Sizing
  • Proper Installation

BATH FAN SIZING

Most builder grade bathroom fans installed today are 50 cubic feet per minute (CFM) fans. These fans provide insufficient ventilation for an average sized bathroom.

A good general rule for bathrooms with 8’ ceiling heights is to allow at least 1 cubic foot per minute (CFM) of ventilation for every square foot of room size for bathrooms under 100 square feet.

For larger rooms, the recommendation is based on adding a minimum of 50 CFM for each toilet, sink, bathtub or shower and 100 CFM for jetted tubs. Generally speaking, the larger the CFM rating of the fan, the faster it will take care of any issues.

We recommend Energy Star 150 CFM fans that run quietly and ensure maximum ventilation because often fans do not perform consistently at the rated CFM on the box. According to Building Professional Institute (BPI), a 50 CFM bath fans only produces around 30 CFM of actual air exchange.

PROPER BATH FAN INSTALLATION

All bath fans should be secured to an insulated duct that is routed through the roof and terminated on dampered roof cap to prevent hot moist air from returning into the home.

While some contractors may recommend exhausting the bath fan through open soffit vents; this does not meet code and is especially risking in cold climates as the warm moist air will rise back into your attic resulting in attic moisture problems.

We also regularly see attic fans that exhaust directly into the attic rather than outside, leading to attic mold, wet insulation, and other moisture issues including wood rot to structural elements of the building.

THE ATTIC EXPERTS

We provide insulation and ventilation services, including bathroom exhaust fans in Chicago and all Suburbs. Call us with questions or request a free attic inspection. We conduct a thorough inspection of your attic insulation, attic ventilation, and other home efficiency related considerations. Call us at 630.941.3800

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