How to Vent an Old House

Before air conditioning and fiberglass insulation, homeowners depended on cupolas, covered porches and open windows to ventilate their houses. This reliance on natural ventilation changed radically as the need for energy efficiency brought new technologies in insulation and sealants. Old houses require new venting to keep moisture from settling in the eaves, where it causes mold or rot. Exhaust fans in bathrooms and near cooking appliances pull excess moisture out of the house but proper venting in the attic keeps it moving up and out of the house.

Chalk line
Drill with bits and hole saws
Soffit vent strips 3 inches wide by 8 feet long
Reciprocating saw
Tin snips
Screw driver
Hammer
Deck screws
Galvanized roofing nails
Rafter baffles
Roof vents
Waterproof construction cement
Waterproof membrane
Membrane or paint roller

Instructions

- 1
  Extend exhaust fan flues through your roof; they should not terminate in your attic. Drill a hole just large enough for the flue extension with a hole saw bit on a drill. Terminate the flue above the roof and caulk around the opening with butyl caulk or sheet metal flashing before replacing any damaged shingles.
- 2
  Flick a chalk line down the center of the underside of the eaves, called the soffit, and cut an opening 2 inches wide -- 1 inch on either side of the chalk line -- with a circular saw set to the depth of the soffit facing. Cut across the ends of the opening with a reciprocating saw. Make the soffit opening as long as possible, leaving 4 to 6 inches of closed soffit at ends.
- 3
  Pull loose fill insulation away from the openings and push fiberglass batts back into the interior.
- 4
  Attach the vent strips, using deck screws. Fit the soffit vent strips across the soffit openings, using tin snips to trim the 8-foot sections, if necessary.
- 5
  Pull batts or loose fill insulation out of the eaves and attach baffles between rafters with deck screws or roofing nails. The baffles will establish a clear channel for air to travel from the soffit vents through the insulation layer into the attic. Replace the insulation up to the baffles.
- 6
  Remove enough shingles to place the roof vent and clean enough space around the roof vent base for flashing -- check the specific model for directions. Cut through the roof with the hole saw bit on the drill or a reciprocating saw to fit the first roof vent. Install static roof vents just below the ridge line or on the top surface of a mansard or flat roof.
- 7
  Attach the static roof vent with waterproof construction cement and roofing nails. Cover the flashing that forms the base of the vent with self-adhesive waterproof roofing membrane, rolling with a roller or paint roller to remove air bubbles.
- 8
  Replace the shingles around the vent.

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