Spray Foam Insulation Attic Ventilation

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

Spray foam insulation attic ventilation. Nothing unusual about that. Both low density open cell and medium density closed cell spray foam can be used in an unvented attic to provide the needed thermal resistance and airtightness. 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. The unvented attic space is considered the most effective and up to date building practice particularly by the spray foam industry.

Unvented attics sometimes called sealed enclosed or encapsulated attics feature insulation on the underside of the roof decking rather than on the attic floor. Ventilation and moisture control in spray foam homes spray foam insulation has been increasing in popularity over the last several years due to. Image courtesy of d7 spray foam insulation houston tx using spray foam insulation in an unvented attic application. What you re looking at there is the place where a power attic ventilator had been.

Earlier this year i got a question about a home that had spray foam insulation in the attic. Becoming more affordable significant long term energy savings sealing restricts air movement through the building envelope. Whereas too little spray foam insulation can leave for thermal bypass because of the complete lack of insulation in the attic. 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 but then the questioner mentioned that the spray foam contractor had intentionally left big holes to the outside by not sealing the gable vents. Attic ventilation and spray foam don t mix that photo above is from an existing home that had spray foam insulation installed in the attic over the master bedroom. 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. The most important thing to remember is to use the correct type of insulation and to ensure it is installed correctly.

Moisture is also another huge issue when it comes to spray foam insulation in an attic.