How can you improve attic ventilation, from easy fixes to roofer jobs?
Short answer. The best value improvements come first and cost the least: seal ceiling air leaks, clear and baffle the soffit intake, and duct bath fans outside. The bigger steps, switching to a ridge vent, adding edge intake and removing competing vents, are roofer projects that cost far less when done with a roof replacement.
Weekend projects
- Seal the attic floor: foam or caulk around wiring holes, plumbing stacks, chases and light fixtures rated for contact, plus weatherstripping on the hatch. Less house air in the attic means less moisture.
- Clear the eaves: pull insulation back from the soffit openings and staple baffles in each bay.
- Fix bath fan ducts: reconnect fallen ducts and make sure each ends at a real exterior cap.
Handyman or trim projects
- Swap solid soffit for vented panels, and cut openings in any plywood behind them.
- Add undereave vents to solid wood soffits between rafters.
- Close gable louvers from inside if a ridge vent already serves the attic.
Roofer projects
- Add or lengthen a ridge vent and remove box vents, turbines or fans on the same attic.
- Install edge intake vents on homes with little or no soffit.
- Add bath fan roof caps with proper flashing.
Skip these
- Adding a powered fan to an attic with weak intake.
- Adding more exhaust vents without adding intake.
- Mixing a ridge vent with box vents to get more area.
If the roof is within a few years of replacement, do the cheap steps now and save the roof work for the new roof. See roof ventilation basics and signs you need a new roof.