Another Attic to insulated before finishing....

kmhjet24 · 06-08-2009, 03:32 PM

Hi everybody,

I have a 1906 masonry wall house with a wooden roof and Spanish tiles on it. I live in Rye, NY (around 90 degrees in the summer and 10 in the winter), The attic has 2 windows, one on each side, each about 10 sqft in total and 5sqft of actual airflow space.
It appears to me that there are no soffit vents and no ridge vent. I have done a lot of research on whether or not to use rafter vents (those styrofoam channels that connect the soffit and the ridge) and came to the conclusion that these only make sense if there are soffit and ridge vents, which isn't the case. So I have begun insulating with R-38 faced fiberglass and wanted to put a vapor retarder on once the insulation is complete and finish with sheetrock. But I am now second guessing my conclusion of not putting the rafter vents in. Any help would be greatly appreciated.

glennjanie · 08-26-2009, 10:37 PM

Welcome KMHJet:
Attic ventilation is very important. If you could install rafter vents the length of each side of the house, you could get by very well without the ridge vent. Maybe install a louvered vent in each window for some relief along with the rafter vents.
Glenn

inspectorD · 08-27-2009, 06:55 AM

If I read your post right, you are installing insulation inbetween the rafters?
This is not good without the vents with fiberglass insulation. You would need the soffit and ridge vents.
If you are insulating the attic floor, you will be fine with the attic gable end vents installed where the windows used to be.
Make sure any vapor barriers you install go to the heated side, this would mean you should use paper face fiberglass with the paper touching the plaster or sheetrock backing.

Another solution to all the attic insulation is a product called nuwool. Then you need no venting.
I try to keep it simple, if you are unsure, contact your local building official or hire a home inspector by the hour for solid advice on what you are doing...if you are still unsure.

GBR · 08-27-2009, 10:49 PM

(those styrofoam channels that connect the soffit and the ridge) Those are called baffles- to keep the insulation away from the roof deck to allow an air flow past the insulation. They are not always needed.

Sounds like you are insulating the rafters (12") with the R-38 faced batts. If you install the Pink Panther product, get the R-38c, with the "c" standing for cathedral. This is smaller in thickness with the air space built-in, yet the material is more dense for the same R-value. Here is a similar question and answer I gave, the last one: insulating vaulted ceiling - DIY Chatroom - DIY Home Improvement Forum

Without soffit vents for your air supply, the attic is very poorly ventilated, even adding gable vents (creating wind-washing), read this: Audel Complete Building Construction - Google Books

As brought out, you need soffit vents (screened louvered holes) in each rafter bay, if cathedral ceiling. Be safe, G

steven · 09-07-2009, 09:53 AM

What is the correct method of insulating a roof on a contemporary home which has 8 inch beams and a rubber roof?

Currenly there are baffels, aluminum in the roof.

thanks,
Steve