Do You Need Attic Ventilation With Spray Foam Insulation

It has been said that insulating with spray foam insulation at the roof line will lead to moisture problems with the roof sheathing.

Do you need attic ventilation with spray foam insulation.

Heat from the house rises up to the attic but when there isn t one the heat rises up to the roof. One huge benefit of the spray foam insulated attic is that conditioned air leakage from the ac furnace duct system is contained and used to condition the attic. It s terrific because it s pretty much the same temperature as the rest of the house all the time. Nothing unusual about that.

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. Cathedral roofs especially need a lot more insulation between the ceiling and the rafters because there usually isn t any attic space. A lot of builders and homeowners are going with spray foam insulation because of the airtightness benefits. High attic humidity often results from spray foam insulation.

All insulation materials require proper venting. Nope you absolutely do not need to ventilate a spray foam house and here s why. When we seal the attic with spray foam it s as tight as a butter tub. The main aim of ventilating the attic space is to allow the air in the home to circulate.

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. Earlier this year i got a question about a home that had spray foam insulation in the attic. 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. Because basically now that attic is a conditioned space. 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. Sometimes humidity levels spike in an attic after a spray foam job.

Moisture is also another huge issue when it comes to spray foam insulation in an attic. However in a traditionally insulated attic insulation on the ceiling the attic is vented.