Intake and exhaust vents are crucial for maintaining proper ventilation in a built-up roof (BUR) system, helping to regulate temperature and moisture that can otherwise damage roofing materials and shorten their lifespan. Proper vent sizing is typically based on the total square footage of the roof and the type of insulation used underneath. The goal is to allow adequate airflow—often around 1 square foot of ventilation per 150 square feet of attic space when a vapor barrier is present, or 1:300 without one. Intake vents, usually located at the eaves or soffits, should draw cool air into the attic or roof space, while exhaust vents placed near the roof ridge allow hot, moist air to escape. To diagnose if your ventilation is adequate, check for signs such as uneven roof temperatures, ice dams in winter, or moisture stains inside the building. A simple DIY check is to observe if air seems to flow freely through soffit vents by using a lightweight piece of tissue or a small ribbon held near the vent on a breezy day.
If you notice poor ventilation, or if your roof is aging and needs assessment, it's best to call a professional roofer who specializes in BUR systems. They can do a detailed evaluation, including measuring airflow and inspecting vent placement to ensure optimal performance and compliance with building codes. When speaking with contractors, ask: "How do you determine the proper intake and exhaust vent sizes for my specific roof and insulation type?" and "What methods do you use to ensure the vents are correctly balanced to prevent moisture buildup while meeting warranty requirements?" These questions help ensure the contractor is knowledgeable about balancing ventilation with roof system performance and manufacturer standards, which protects your roof investment over time.