Bath, Laundry and Range Hood Exhaust: Getting Ventilation Right in New Homes

Oct 5

2 min read

Exhaust and dryer venting are small parts of the mechanical scope, but they show up on inspection reports and in moisture problems after closing.

Bath exhaust fans

Ducted all the way to the outdoors, never into the attic or through a soffit intake vent.
Duct sized for the fan and kept as short and straight as practical.
A backdraft damper at the fan or termination, and a hooded exterior cap.
Duct in unconditioned space insulated where needed to limit condensation.

Laundry and dryer vents

Rigid metal duct with smooth joints, as the code and dryer manufacturer require.
Total length and number of elbows within the manufacturer's limits.
Termination outdoors with a backdraft damper and no screen that can catch lint.
Dryer location chosen early so the vent run stays short.

Range hoods

Duct to the outdoors when the hood is designed to exhaust, with the duct size the hood requires.
Large-capacity hoods can trigger makeup air requirements under the adopted code; check the model before the cabinets are ordered.
Plan the route through cabinets, joists and the roof or wall before drywall.

Whole-house ventilation

Tighter new homes often need mechanical ventilation, such as an ERV or a balanced or exhaust-only system, as required by the adopted energy and residential codes. Coordinating it with the HVAC design keeps the system simple and quiet.

Before the inspection

Check every termination from the outside, confirm dampers are installed and make sure no exhaust ends in the attic. See our rough-in inspection checklist for the rest of the mechanical scope.

Planning a project?

DML Mechanical LLC is a Utah-licensed HVAC contractor (DOPL B100 · S350) for builders and general contractors on residential and commercial new construction across the Wasatch Front. Send us your plan set for a line-item bid, or call (385) 307-8871.