Insulating and Venting Your New Roof
Few things are more misunderstood about the home than attic ventilation. Good roof ventilation reduces cooling bills, extends shingle life, and prevents roof rot and ice dams in winter. Both roof and soffit vents will protect your house from expensive future repairs. And, while it sounds simple, it’s not.
There are various venting options, as well as the option to not vent. The choice of venting or not venting is a design and construction choice not a requirement determined by the physics or by the building code.
Yes, we know, it sounds confusing. Let us break it down for you.
Advantages of Ventilation
The installation of roof vents is a crucial part of roof design because it allows for proper attic ventilation, which may help prevent condensation and early aging of your roofing materials.
Proper attic ventilation offers numerous advantages to the homeowner:
- As the ventilation helps moderate the temperatures in the attic, this will also help moderate the temperature in the rest of the home.
- It helps prevent moisture buildup in your attic, which, during colder months, can help prevent condensation issues that can affect the materials in the attic space, especially insulation.
- By preventing excess heat buildup, proper ventilation promotes energy efficiency in the home, so your heating costs may be lower.
- It helps protect the life of the roofing materials (condensation is a leading cause of damage to roofing materials, such as asphalt roofing shingles).
- It helps you remain compliant with most local building codes, which often require proper attic ventilation in homes.
Attic and Roof Vents
When done correctly, attic venting can reduce the potential for condensation in winter and summer. During winter, the primary cause of attic moisture issues stems from warm moist air infiltrating into the attic space from the inhabited areas and condensing on cold surfaces. This can be intensified when lights, pipes, vents, and other penetrations pierce the attic floor.
A combination of air-sealing and insulating the attic floor while providing ventilation, considerably reduces the potential for condensation, as warm moist air is less likely to enter the space and condense on cold surfaces. As a result, cooler, less humid air from outside can be drawn in from soffit vents placed on the roof’s lower portion, and flow through to rooftop or ridge vents, replacing the warmer moist air that may have infiltrated into the attic.
Unvented attics rely on an air-impermeable insulation installed to the roof deck’s underside or the attic ceiling to stop airborne moisture from reaching a cold surface and condensing inside the building envelope. In this design, insulation effectively separates the interior and exterior spaces while slowing down moisture flow so the dew point is not achieved within the building envelope.
The two products most often used in an unvented attic assembly are medium- and low-density sprayed polyurethane foam (SPF).
Ventilation is important to many different aspects of the home. The comfort of the homeowner, the life expectancy of the roof and the performance of the heating and air conditioning system can be affected by ventilation.
If you are concerned about your ventilation, contact the team at All-Nu Construction. We are roofing experts. Let us help you make the best choice for your home.