Insulation, Radiant and Vapor Barriers - Vaulted Ceiling
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Renty59
05-02-02, 06:25 PM
I just purchased a 35 year old house in CA. At the time of purchase it was a repo and was bought as is from the bank.It had a den added on but, it wasn't permitted. Now, the city I live in is going thourghout the city looking for unpermitted additions. I thought I'd head them off at the pass by having the addition brought up to code. What a nightmare. 30,000 and counting. Anyway, the latest request from the inspector is that our vaulted ceiling needs to be insulated with R-30. My ceiling does not have any space between the roof and the ceiling. It consists of asphalt shingles on tar paper over 2x8's. How would i go about insulating
this mess and does 30 seem high for So. Cal.?My other question is; does the 2x8 have any insulating properties?
Thanks for your help in advance.
Renty
this mess and does 30 seem high for So. Cal.?My other question is; does the 2x8 have any insulating properties?
Thanks for your help in advance.
Renty
resercon
05-12-02, 11:56 AM
Yes 2x8's do have insulation value, however, the building inspector does not consider that as far as insulation requirements are concerned.
You have basically 2 choices to meet his requirements. One is to raise the roof to the point where there is enough space to accomodate the R-30. The other is to lower the ceiling to accomplish it. The latter seems to be the most feasible and cost effective.
The way to accomplish it is by removing the sheet rock and installing 6 inches of unfaced fiberglass insulation between the rafters (R-19), leaving a 2 inch dead air space between the insulation and roof. Then install rigid board insulation over the rafters equal to R-11.Then sheet rock over the rigid board insulation. You should document the entire process by keeping receipts and rating lables of products installed for the inspector. I would even go as far as taking pictures of the procedure to show him you met his requirements.
Before you start you should seek the inspector's advice to determine if it will satisfy his concerns and if there are any other requirements, especially structural supports like bracing concerning earthquakes. You'll find these braces are relatively inexpensive and very easy to install. Also if there are any ventilation requirements and fire stops. Again, it's inexpensive and easy to install. You may have to install 1x2 inch slats 16 inches on center over the rigid board insulation to provide adequate nail surface for the sheet rock. You may want to ask him which is the acceptable method for securing the sheet rock. For example nails may be required to be no more than 4 inches apart and screws 8 inches apart. Nails may not even be allowed when using slats. You should ask the inspector.
If you did this yourself, it will take you a few weeks and material cost should be considerably less than a $1,000. As long as there no electrical or plumbing to do. If you have a contractor do it, it's going to take a little bit more than a week to accomplish and should cost more than $5,000.
You have basically 2 choices to meet his requirements. One is to raise the roof to the point where there is enough space to accomodate the R-30. The other is to lower the ceiling to accomplish it. The latter seems to be the most feasible and cost effective.
The way to accomplish it is by removing the sheet rock and installing 6 inches of unfaced fiberglass insulation between the rafters (R-19), leaving a 2 inch dead air space between the insulation and roof. Then install rigid board insulation over the rafters equal to R-11.Then sheet rock over the rigid board insulation. You should document the entire process by keeping receipts and rating lables of products installed for the inspector. I would even go as far as taking pictures of the procedure to show him you met his requirements.
Before you start you should seek the inspector's advice to determine if it will satisfy his concerns and if there are any other requirements, especially structural supports like bracing concerning earthquakes. You'll find these braces are relatively inexpensive and very easy to install. Also if there are any ventilation requirements and fire stops. Again, it's inexpensive and easy to install. You may have to install 1x2 inch slats 16 inches on center over the rigid board insulation to provide adequate nail surface for the sheet rock. You may want to ask him which is the acceptable method for securing the sheet rock. For example nails may be required to be no more than 4 inches apart and screws 8 inches apart. Nails may not even be allowed when using slats. You should ask the inspector.
If you did this yourself, it will take you a few weeks and material cost should be considerably less than a $1,000. As long as there no electrical or plumbing to do. If you have a contractor do it, it's going to take a little bit more than a week to accomplish and should cost more than $5,000.
Insulman
05-13-02, 03:27 PM
Another option to consider is installing 2" x 2"'S or 2" x 4"'s on the underside of the 2" X 8" s . If you use 2" x 2"s you the should be able to utilize an R-30 high density bat which is 8 1/4" thick or if using 2" x 4" s you can then install standard 10" R-30 batt...
High Density batts are not generally found at the local Home Depot type store... Usually you can find them at a local Insulation Wholesaler who supplies smaller insualtion company's and drywall company's..
Good Luck
Jim
High Density batts are not generally found at the local Home Depot type store... Usually you can find them at a local Insulation Wholesaler who supplies smaller insualtion company's and drywall company's..
Good Luck
Jim