Do Attics With Spray Foam Insulation Need Ventilation

The ventilation helps to keep the air fresh in the home the insulation stops warm air from escaping and cold air from leaking in.

Do attics with spray foam insulation need ventilation. Earlier this year i got a question about a home that had spray foam insulation in the attic. When we seal the attic with spray foam it s as tight as a butter tub. Some know more than others of course but you should probably assume the worst any time a roofer comes to your spray foam insulated home. Nothing unusual about that.

We also recommend to do no harm when we. 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. It has been said that insulating with spray foam insulation at the roof line will lead to moisture problems with the roof sheathing. However in a traditionally insulated attic insulation on the ceiling the attic is vented.

They know roofing materials underlayments flashing and attic ventilation. Because basically now that attic is a conditioned space. Whereas too little spray foam insulation can leave for thermal bypass because of the complete lack of insulation in the attic. Sometimes humidity levels spike in an attic after a spray foam job.

Unvented attic assemblies unvented attics rely on an air impermeable insulation installed to the roof deck s underside i e. But then the questioner mentioned that the spray foam contractor had intentionally left big holes to the outside by not sealing the gable vents. Mechanical ventilation systems allow a constant flow of outside air into the home and can also provide filtration dehumidification and conditioning of the incoming outside air. I have a spray foamed attic.

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 dewpoint is not achieved within. It s terrific because it s pretty much the same temperature as the rest of the house all the time. 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. A lot of builders and homeowners are going with spray foam insulation because of the airtightness benefits.

Therefore providing mechanical fresh air ventilation is especially important in spray foam houses. Nope you absolutely do not need to ventilate a spray foam house and here s why. High attic humidity often results from spray foam insulation. They need the right level of ventilation but they also require insulation in order to help improve the energy efficiency of the property.