How do you check your attic ventilation yourself?
Short answer. Start outside by identifying every intake and exhaust vent and reading their ratings where you can, then go into the attic on a bright, cool morning to look for daylight at the eaves, baffles in place, clear insulation and clean, dry decking. A thermometer reading in late afternoon and again after sunset tells you how well the attic sheds heat.
Outside, from the ground
- Look under the eaves for vented soffit, strip vents or undereave vents. Note where the soffit is solid.
- Look at the roof for a ridge vent, box vents, turbines or a fan. More than one type on the same attic is a red flag.
- Note gable louvers on the end walls.
Inside the attic
- Go early in the day, when it is cooler, and bring a flashlight and a dust mask. Step only on framing.
- Turn off the light and look toward the eaves. Daylight or open baffle channels in most bays means intake is open.
- Look toward the ridge for a strip of daylight along a ridge vent slot.
- Check the decking for dark staining, especially on north slopes, and nail tips for rust.
- Check the insulation for dampness or compression at the eaves.
- Look for bath fan ducts that end in the attic instead of at a roof or wall cap.
The temperature check
On a sunny summer day, read an inexpensive thermometer left in the attic in late afternoon and again a couple of hours after sunset. A hot afternoon is normal in Georgia. An attic that stays very hot long after dark suggests weak airflow.
The paper test
On a breezy day, hold a tissue near a soffit vent outside. A gentle pull inward suggests air is moving in.
Compare what you found with the numbers in roof ventilation basics and the symptoms in attic heat and shingles.