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Mr. Shed 02-15-2011 10:16 AM

Venting if there is no soffit.....
Hey can anybody tell me if there is a point to putting the styrofoam rafter vents in if there is no soffit (no air movement) in the roof bays.

I am refinishing the second floor MBR/Bath of my cape, it is 2x6 24" oc and I would like to insulate it as best as possible because I have a black roof, which is great for heat gain in winter but terrible for keeping it cool up there in summer. There is a ridge vent at the peak and some venting in the front, but there is no soffit at all in the rear.

Once I put those rafter vents in I am only left with 4" of depth for insulation so I wanted to see if it is pointless to install them with no air flow on the back roof of the house.


Gary in WA 02-16-2011 12:03 AM

Where are you located?


Mr. Shed 02-16-2011 04:54 PM

I am in central NJ, the ridge vent was installed when the roof was done about 4 years ago because there is the ability to install venting in the front of the house if I took off the trim coil and vinyl soffit and drilled some holes in the old plywood soffit underneath. There is no soffit at all on the rear of the house and my only option would be pulling off the lower courses of shingles to install a smart vent, which I am not even considering.

I actually just got a quote on going with open cell spray foam insulation on the entire upstairs creating a completely sealed attic (well only the top 3 or so feet is actual attic, the rest is, or will be the wall of my bedroom) they said they just cover the inside of the ridge vent with plastic so the foam doesn't expand out the venting while curing.

The open cell foam may be the way I go, the house has a black roof in full sun all day and I think I will regret putting fiberglass and useless venting in there. I'm an electrician by trade and I've been in some attics with the foam, it amazed me how the attic was nearly the same temp as the living space below.

Mr. Shed 02-16-2011 04:59 PM

Here is a photo of the house:

Mr. Shed 02-18-2011 04:42 PM

So I've read up on the open cell foam over the past few nights and have come across some success stories from folks using the open cell foam as insulation for unvented finished attic spaces but I still am up in the air about the fact that my house has a ridge vent and I am not sure if this ridge vent will cause any issues with the foam insulation once I close everything off.

Once everything is finished off and rocked the leftover actual attic space is very small, basically just above the windows in the pic above there are 2x6 collar ties, only a scuddle less than 3' high remains with the ridge vent at the peak the whole length, the underside of the roof deck will be filled with open cell 5.5 deep all the way to the ridge vent.

Any opinions on this installation anyone?

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