No Need For Ventilation With Cellulose?
I am converting the attic of an 80 year old farm house to a finished space. I added three large dormers and tied all of the dormer ventilation channels as well as the top of the central cathedral ceiling together and added a thermostatically controlled fan at the peak of the roof cavity. I used a form of Pro-Vent which resists collapse.
I then had a well respected cellulose insulation company apply the insulation. I learned later as I began to install the drywall, that they blew in over 24 inches of cellulose to the very top of all the cavities, effectively killing all ventilation. They also failed to install the what little remaining Pro-vent was necessary into the top of the cathedral cavity. I had to shop vac out over 20 large trash bags of excessive cellulose that were ballooning out between the studs so that we can install the 5/8″ drywall without popping the screws. My electrician and the drywall experts helping me all believe that the cellulose folks went wild.
I removed some cellulose to open nominal channels above the cellulose layer to create ventilation between the decking and the insulation and removed the 30″ of impacted cellulose from the immediate fan area.
I contacted the owner of the cellulose company and he stated in a fax: “the use of vent chutes are not necesary with this system (spray application) of insulation in cathedral ceiling areas. Certaintee has been a leader in the roofing industry and has approved this system…(and that it would not) effect the life of the decking or (shingle) material.”
This is contrary to everything I have ever read before. The owner stated that if the insulation was fiberglass that ventilation was necessary, but since the cellulose is more dense (and they put in loads!), ventilation channels are not needed.
Help! What’s the real story?
Replies
There has been a LOT of discussion here. Try the Search function and dig in!
Edited 12/6/2006 8:23 pm ET by rjw
Thanks. I checked out quite a bit. I'm new to the online forum. Been reading the printed excerpts in Fine Homebuilding for years.
welcome to Breaktime - there are alot of pewople with a lot of knowledge here.
Edited 12/6/2006 8:25 pm ET by rjw
Here is some more info, tho perhaps a bit biased.
http://www.regalind.com/regal_wall.htm
Also this ( a very good resource)
http://www.buildingscience.com/
Thanks. I read some of the information in Building Science. I believe I'll get my PhD first, then go back and see if I can absorb maybe 50% of it; up from the 25% I understand now.
Thanks!