Do Attics With Spray Foam Insulation Need Ventilation

High attic humidity often results from spray foam insulation.

Do attics with spray foam insulation need ventilation.

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. 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 s terrific because it s pretty much the same temperature as the rest of the house all the time. Moisture is also another huge issue when it comes to spray foam insulation in an attic.

They need the right level of ventilation but they also require insulation in order to help improve the energy efficiency of the property. Unvented attic assemblies unvented attics rely on an air impermeable insulation installed to the roof deck s underside i e. 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.

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. Sometimes humidity levels spike in an attic after a spray foam job. Nope you absolutely do not need to ventilate a spray foam house and here s why.

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. Do attics with spray foam insulation need ventilation. Nothing unusual about that.

However in a traditionally insulated attic insulation on the ceiling the attic is vented. The ventilation helps to keep the air fresh in the home the insulation stops warm air from escaping and cold air from leaking in. They know roofing materials underlayments flashing and attic ventilation. 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.

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. Whereas too little spray foam insulation can leave for thermal bypass because of the complete lack of insulation in the attic. Because basically now that attic is a conditioned space. When we seal the attic with spray foam it s as tight as a butter tub.