Roof ventilation question

I inspected this house last week. Built in 2009, on the beach. There were ridge vents or static vents visible on 2 roof areas. These areas did have soffit vents. Both of these areas have vaulted ceilings inside. I report that there is not ridge ventialtion in these areas.

The buyer asks the builder (home has been for sale for 3 years) to make repairs and add vents. The builder responds with this:

“Those areas have cavities between the rafters completely filled with a high density blown cellulose insulation with eliminates any air space to be vented and is in compliance with building code”

I am incorrect to think that these areas should be vented with soffit and ridge vents with vent chutes in between?

Can someone please enlighten me on this. I have not replied to the buyers email or called them yet.


My question is: Doesn’t the roof still need to be vented even though its a vaulted ceiling with blown in cellulose? I thought it was only spray faom that didn’t require ventilation.

I think not ,if no air can get in then no can get out .
Sealed at both ends to me then no vent required… Roy

Thanks Roy

Nathan, I admit I am not familiar with high density blown cellulose but I am concerned with a concept that relies on the contractor/builder/installer to properly install the product so that no air pockets remain. I look at your pictures and see an uneven melt pattern in the snow. I know it could be wind and sun exposure causing the inconsistent pattern but it could also be heat loss indicating air flow. Just another take. Perhaps it shows my cynicism when dealing with builders.

Yes, it needs to be ventilated and this is usually achieved by installing cardboard or foam baffles that create a 2" airspace just below the sheathing. Lack of sheathing ventilation will void the manufacturer’s warranty and shorten the lifespan of the shingles. The pattern you see in the third picture is caused by thermal bridging where the rafters transfer heat to the sheathing resulting in more rapid melting. See how the pattern aligns with the rafter tails?

If there were ridge vents, why would you report that there were no ridge vents?

Have your client request the builder supply them with the ASTM installation instructions for that product.After review they will be able to negotiate the type of ventilation system to be retro-fitted. Building codes require that materials must be installed in accordance to their listing.
Good catch if the insulation is in deed filling the whole cavity of the vault as the builder claims the pictures you included will just be the tip of the iceberg. Will have moisture issues.