Insulation conundrum

[Jim Krapf]

Are there any building inspectors on here?
I have a problem with insulating a couple valleys on addition that I'm doing, It's a ranch house and I put an addition on where the roof runs perpendicular or at a right angle, imagine a capital T Where the addition meets the ranch there is no way to ventilate the rafters because they end in each valley. The length of the addition is the same as the width of the house.
The addition is going to have a cathedral cieling.
Inspector says that because that it can't be vented that I have to have the sprayed in expanding foam stuff. That's a great Idea and I understand what he's saying but is there an alternative method that I can use, like using poured in styroam beads or by using the thick foam sheets cut to fill the void between each rafter. Please help
Jim K
P.S I plan on using my ford tractor to lift the insulation up to the addition when I do this job.

 

[Janicholson]

Inspectors are often flexible on type of insulation if applied according to manufacturers directions, and accompanied by all needed moisture barriers. Google the isue to find manufacturers of rigid foam, and their application to that construction practice. With that info, and info from a local supplier of the material you want to use, go with pictures and circles and arrows indicating your alternative. With approved material in your hand to show you will go far toward getting your change. JimN

 

[tlak]

The point of the sprayed in is, the area becomes like the inside of the house and does not need any venting. Your house becomes a big ice chest.
The other system I saw was large Styrofoam blocks sandwiched between boards that would be your exposed ceiling and boards that will be your roof. These are not the structural Styrofoam panels, but manufactured on site.

 

[Vito]

A couple of questions:
Did you over frame the valley onto the main roof or was it framed with a structural valley?
Will the inspector allow a prop vent( 2 "channel of styrafoam)
What state do you live in?
I am a carpenter by trade but have 10 plus years in residential construction management.
Email is open.Would be glad to help as much as I can.
Vito

 

[Jim k]

I live in mass. The two roofs are the same hight It's just that one side is up against the house and the addition part is going to be cathedral cieling.

 

[Anonymous-0]

Maybe considering what venting does is the approach needed. My understanding is to vent out humidity and avoid over heated roofing. I don't see why fiberglass with a gap from the roof sheathing, a good vapor barrier below and a vent at the peak wouldn't work. Wouldn't sprayed in foam overheat the roofing?