How to Vent a Foam Insulated Roof

Before looking into how to vent a foam-insulated roof, you should understand the difference between open cell foam insulation and closed cell foam insulation. Open cell foam has cells that are interconnected and allow for air to flow through while closed cell foam has interconnected cells that do not allow for any air to pass through. Open cell foam insulation has superior soundproofing as compared to closed cell insulation, but it has inferior insulating value. Closed-cell foam insulation has greater resistance to water and mold. If you are going to vent your roof, you should choose to install closed-cell insulation.

Foam Insulation Venting Requirements

In general, foam insulation does not require venting. This is because foam insulation has a high R-value, which means it is very resistant to heat flow. This also makes it resistant to air flow. However, there are some cases where it is necessary to vent foam insulation. Venting is necessary when your attic has signs of moisture, like dripping condensation, frost on the roof in the winter, mold or mildew growth, rotting roof sheathing or rafters, or rust on metal fasteners. You may notice that in the summer months, your home is very warm, or there are icicles forming along your roofline in the winter months. When in doubt, it is always best to consult a building professional.

Roof Venting Strategies

Attic Fan Installation: Installing an electric gable vent or powered roof vent in your attic is a simple way to help move warm and moist air out of the attic.

Soffit Venting: Install louvered soffit panels to allow cool air to enter the attic through your soffits. It is recommended that you cover about 10% of your soffits with vents to ensure proper ventilation.

Ridge Venting: Install a ridge vent along the peak of your roof allows hot air to escape easily. If your roofline has any type of penetrations, such as a skylight or a chimney, you will want to install a continuous ridge vent to ensure good air circulation across your entire attic.

Baffle Installation: Venting baffles should be installed between your roof rafters and your insulation. This will allow air to flow from your eaves up to the ridge and out through the ridge vent.

Always consult with a professional roofer in your area to understand the best venting strategies for your roof’s specific needs.