Roof Venting With Spray Foam Insulation

Foam insulation can play an important role in both vented and un vented roof assemblies.

Roof venting with spray foam insulation.

This spray foam is applied as a low or high pressure two component polyurethane spray foam that can be applied onto walls in unvented attics to ducts and ceilings and in vented attics and crawl spaces. It rots roofs people have told me. 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 movement of air into indirect conditioning of an unvented attic is a slow gradual process that will not be noticeable by occupants and typically will not put any strain on the hvac system.

How to vent a foam insulated roof step 1. Learn how the need for roof vents are determined. You re looking to insulate your attic and are wondering if you need roof vents with spray foam insulation. Unvented attic assemblies unvented attics rely on an air impermeable insulation installed to the roof deck s underside i e.

Becoming more affordable significant long term energy savings sealing restricts air movement through the building envelope. Leave a gap on both sides. Not long ago someone even told me that in florida roofing companies won t let their workers go up on roofs with open cell spray foam because the roofs are so spongy the guys fall right through. Temporarily secure long plastic forms between the rafters on the inside of the ceiling.

Spray foam insulation has been increasing in popularity over the last several years due to. In a vented roof foam can seal the openings and serve as an air barrier and a vapor retarder in addition to its insulating function. Build the rafters and secure the 5 8 inch cdx sheathing material. An open cell foam low density spray polyurethane is a spray applied to provide continuous insulation and an air sealing barrier.

It works great as long as there is no moisture which will significantly decrease r value but when you vault a space and spray in open cell foam rising humidity can really soak that foam over time and holding moisture next to wood is not exactly best practice especially in southern humid environments. But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used. Murmurs and hearsay about open cell spray foam insulation have been gaining traction for a while. In an un vented roof foam can serve as the air barrier and vapor retarder and prevent moisture from getting in to the roof cavities.