Older home insulation

[Marc]

We purchased our first home last spring and the home inspector highly recommended we further insulate the attic before the winter season. The house was built in 1958 and is located in Ottawa, Canada where it does get quite cold during the winter months. Right now we have about 6 inches of blown in fiberglass (White in color but has the texture of fiberglass) that fills the ceiling joist cavities. I am unsure what the exact R-value of this type of insulation would be but I would assume it would be approximately R-20.

1) What R-Value should I be aiming for? 2) I was thinking of installing rockwool bat insulation perpendicular to the ceiling joists on top of the old stuff. I was wondering if I should just remove all the old stuff and re-insulate with new material. 3) It looks like a wax paper type vapor barrier was installed. How effective would this type of vapor barrier be? I am assuming that barrier along with the several coats of alkyd paints that were applied to the ceiling over the year should be sufficient?

Any advice would be much appreciated,

[SQLit]

I had ~ 5 inches of fiberglass appearing stuff, in my attic. I believe I found out that was R-11 or 12. The US government has LOTS of sites that will tell you what R value you should install. My area in Arizona was R-30, R-38 and R-45 depending on what site I went to. Neet 3 different answers for what I thought was a simple question.

I decided to have installed R-30 cellulous over the existing. Mostly cause it was cheaper than doing it myself and I do not crawl well now days. Cost me ~$350.00 US for 1000 sqft. I did mine in the end of July. August's electric bill just showed up and it was 50% less than the July electric bill. My load is not for heating but for air conditioning.

Assuming that I had R-10 in the attic and installed R-30 that would give me something close to R-40. I would call some blown insulation contractors in your area before getting dirty. They might have a pleasant surprise for ya.

What should you shoot for,,,,,,,, R-50? What do the new homes in your area have? That would be the minimum code. I can not think of a reason to not exceed minimum in this case. We can not even buy rock wool any more here. Keep the old and install new over it. Can not hurt.

[Marc]

Thanks for the feedback guys. I had another question I forgot to include in my first post. The inspector also told me it would be a good idea to install a ceiling fan in the stairwell leading to the second floor. This fan would help push warm air down in the winter months? Question is, would this be cost effective if you consider the power being used by the fan and if so, should the fan be operated 24/7 during the heating season?

Cheers

Marc

[C & M]

This won't be much help, but don't waste the insulation that you have. Proceed with your plan of perpendicular installation of batts. My home is the same and I installed the thickest batts I could lay my hands on. I definitely helped although I can't give you a cost/ benefit ratio because we heat with wood. It does seem easier to keep the place cool in the summer and warm in the winter. I agree with you on the vapor barrier too. HTH

[barry]

Not likely- for winter. Much more likely for whenever in spring or fall, or summer nights.

Be sure that the door is well-sealed and insulated too. And that attic is vented, above insulation, of course.

HTH, J