Do You Need Attic Ventilation With Spray Foam Insulation

Cathedral roofs especially need a lot more insulation between the ceiling and the rafters because there usually isn t any attic space.

Do you need attic ventilation with spray foam insulation.

Whereas too little spray foam insulation can leave for thermal bypass because of the complete lack of insulation in the attic. Ventilation is required but not all ventilation options are appropriate for the home or homes with spray foam insulation. The main aim of ventilating the attic space is to allow the air in the home to circulate. Because basically now that attic is a conditioned space.

Therefore providing mechanical fresh air ventilation is especially important in spray foam houses. Heat from the house rises up to the attic but when there isn t one the heat rises up to the roof. Earlier this year i got a question about a home that had spray foam insulation in the attic. It has been said that insulating with spray foam insulation at the roof line will lead to moisture problems with the roof sheathing.

Moisture is also another huge issue when it comes to spray foam insulation in an attic. All insulation materials require proper venting. A lot of builders and homeowners are going with spray foam insulation because of the airtightness benefits. Nope you absolutely do not need to ventilate a spray foam house and here s why.

Nothing unusual about that. Sometimes humidity levels spike in an attic after a spray foam job. If a blower door test reveals that your spray foam insulation reduced ventilation beyond an acceptable level you may need to install one of these units in your home. Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air pollutants out of the home this can lead to health problems.

However in a traditionally insulated attic insulation on the ceiling the attic is vented. A combination of air sealing and insulating the attic floor while providing ventilation considerably reduces potential for condensation as warm moist air is less likely to enter the space and condense on cold surfaces. When we seal the attic with spray foam it s as tight as a butter tub. Rigid foam and spray foam are two of them.

But then the questioner mentioned that the spray foam contractor had intentionally left big holes to the outside by not sealing the gable vents. I have a spray foamed attic.