Massachusetts residents have concerns about ice dams and heavy snow loads. However, poor roof ventilation causing moisture damage is also a significant problem. The combination of cold surfaces in the attic and the warm air from your house during the winter results in condensation forming where you cannot see it, creating a great deal of moisture-damage before the homeowner realizes there is a problem.
Balancing Intake and Exhaust Vents To Create Air Flow Through Attics In Massachusetts Winters
Balanced ventilation occurs when intake vents pull cool, dry air into the attic space, while simultaneously exhaust vents push the warm, moist air out of the attic space. Warm, moist air is continuously created within your home from cooking, taking showers, washing clothes, etc., and from simply breathing. That warm, moist air will find its way into the attic space through small gaps in the ceiling due to natural convection.
If there is no proper ventilation, the moisture-laden air becomes trapped within the attic space and upon contact with the cold underside of the roof deck, condensation occurs as well as when water droplets form on a cold drink on a warm summer day. In the winter, that condensation typically freezes into frost which may go unnoticed. It is when the temperatures increase and that frost thaws into liquid that damage to the roof sheathing, insulation, and wooden framing members begins.
Soffit vs Ridge Vents – A Comparison Of Intake And Exhaust Vents
To function properly, roofs require both intake and exhaust vents working together. Soffit vents serve as the intake opening located under the eave of your home where cool outside air enters. Ridge vents serve as the exhaust opening located along the peak of your roof where the hot, moist air naturally escapes as it rises.
Together, these two types of vents create a process known as balanced ventilation. Consider it similar to breathing – you require both an inlet (intake) and outlet (exhaust) for the system to operate correctly. If you only install ridge vents and do not install soffit vents, you are essentially attempting to exhale without inhaling – the system will not be able to move sufficient amounts of air to eliminate the potential for moisture-related issues.
Ventilation baffles are installed above the soffit vents and below the roof sheathing to ensure that insulation does not block airflow. Without these baffles, insulation will settle over time and cover the soffit vents eliminating the reason why they were initially installed.
Hidden Damage From Poor Roof Ventilation
Damage from poor ventilation appears gradually. Homeowners may observe rusty nail heads protruding from their roof sheathing. Mold and mildew grow on wooden rafter material and plywood decking. Insulation compresses and becomes saturated with water and loses its insulating properties regardless of whether the insulation has dried out.
The most severe damage occurs within the wall cavity where water drips from the attic space into the wall cavity and becomes trapped between the exterior sheathing and interior vapor barrier. This unseen moisture causes decay of wood materials, corrosion of metal fasteners, and the growth of mold that is not visible until a homeowner detects the presence of mold by odor or observes peeling paint on walls weeks/months after the initial water leak occurred.
Ventilation Requirements For Residential Roofs In Massachusetts Under State Building Code
The Massachusetts building code states that residential roofing must provide 1 square foot of free ventilation area per every 300 square feet of attic floor space. Also, the free ventilation area must be divided equally between intake vents (soffit) and exhaust vents (ridge vents). Therefore, if a roof has 1200 square feet of attic space, then 2 square feet of soffit venting and 2 square feet of ridge venting must be provided.
The building code requirements exist because the extreme temperature fluctuations caused by the cold winters and heated homes in Massachusetts create ideal conditions for the formation of condensation.
Roof Ventilation Can Only Be Installed At Time Of Roof Replacement
Proper ventilation can never be retrofitted onto a roof. Ridge vents must be cut through the roof sheathing along the peak of the roof and installed in conjunction with a specific type of shingle cap system to prevent leaks. Soffit vents must be aligned with ventilation baffles located within the attic.
As a CertainTeed SELECT ShingleMaster, at Marios Roofing, all of our new roof installations include a balanced ventilation system. We follow all applicable state and national installation guidelines, including those related to proper ventilation to prevent damage to the roof structure from moisture accumulation during the winter months. Do not consider ventilation an afterthought – it is an essential component for protecting your home from the moisture-related problems associated with winter conditions. Contact us today at (781) 269-9166 to schedule a consultation to determine how a properly ventilated roof protects homes throughout Massachusetts year round.