DIYbanter - View Single Post - rock wool insulation in attic replace or add to it?

larry moe 'n curly

wrote:

On Jun 30, 3:00�pm, Joe wrote:

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.

appears rock wool and fiberglass are same per inch, around 3

closed cell foam is over r6 per inch.

i would pull up the rock wool and replace with closed cll foam

Only if it's completely covered with plaster or drywall, right?
Because foam burns like crazy and must never be left uncovered. I
don't think any codes allow it to be left exposed. If covering the
insulation isn't possible or practical, there's dense fiberglass, also
rated about R-6 per inch, that's safe to leave uncovered.