wrote in message
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On Jul 1, 12:09 am, "Bob F" wrote:
"Joe" wrote in message

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I have rock wool insulation stapled to the rafters of my cape cod
built in 1952. It's in pretty good shape but I'm not sure if it should
be replaced or augmented. My 2nd floor is always a degree or two
colder than my 1st floor in the winter so I decided I'm in need of
some insulation. I checked and noticed that where the dormers were
added there is a lack of insulation. A handyman I had doing other work
on my house said that the wool insulation is better than the
fiberglass and I should keep it and just add some insulation to the
knee joints near the dormers where it is lacking and that should be
enough. I'd like to take care of this correctly so I'm wondering what
the conventional wisdom of rock wool insulation is. Is there an R
value for it?

I assume that the area under the rafters is heated. If not, the insulation is
normally between/above the joists at the top of the ceiling of the heated
area.

Well, it's a cape cod which means that the 2nd floor is basically the
attic and the areas I'm talking about are the crawl spaces where there
is no head room. They are generally closed off and used as storage
space. The places where we have rock wool insulation are parallel to
the heated living area and cordoned off by dry wall so there is a need
to have the insulation against the roof. I don't have access to the
attic so I'll need to cut a hole in the ceiling to see what is up
there but I assume that is rock wool as well. There I assume I can do
the standard type of insulating right above the ceiling.

I'd hate to take down the rock wool since it doesn't seem to be
degraded in any way, my preference is to add insulation over it. Can I
just staple fiberglass over it or is spray foam my only real option
due to the gravity situation?

You can add more over it. What you add should not have a vapor barrier. In flat
areas, you can just lay batts down over the old.