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,
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
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.
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?
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.
This won't be much help, but don't waste the insulation that you have.
your plan of perpendicular installation of batts. My home is the same and I
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
cool in the summer and warm in the winter. I agree with you on the vapor
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