"Joseph Meehan" wrote in message
...
wrote in message
oups.com...
I'm planning on adding a layer of insulation to the attic. There's an
existing ~6" or so on the floor of the attic, between the rafters.
It's old and probably the original.

I'd like to add another layer.

Would it make sense to roll out another layer on top of the original
at a 90° angle to the rafters, or, put a layer up against the roof and
between those rafters?


Adding it over the existing insulation is the way to go. Putting it
under the roof will bring up possible problems with vapor barrier and it
will increase the temperature of the roof which will shorten the life of
the roof.

Note: Take any opportunity to increase the passive ventilation of the
attic.

To follow up on that, I'd suggest the OP replace bathroom fans now if they
need to be and vent them to the outside if not already done. Once there's a
bunch of insulation up there those projects are not fun.