Home insulation

Tom,
I read your artice n the Bangor Daily news and I am interested in doing
more to insulate my house this year. I was wondering you could answer a
few questions?
I have a 1500 sf ranch built in 1962. I blew 12'' of cellulose in the
attic a few years ago. The walls are 2x4 except for a new addition.I have looked at putting 2" foam on the outside. I would have to take all my siging off and windows out. Putting 2" of foam on the inside may be
easier because I would not be rushed by the weather. I can do one room at
a time. I am worred about condensation if I put foam on the inside of the
walls or if I stud up another wall on the inside.
The foundation is not insualted and escavation in not possible. The
basement is not finished nor heated. Floow is not insulated. I have a low
mass boiler in the basement but it is oversized I believe. The cellar does
not seem to be moist when we get a ton of rain I am dependant on my sump
pump.
Do you have a guide to home insulation or can you give me some
recommendations? Do you know of anyone that does the insulating? I use
about 1000 gallons of oil per year for heat and hot water.
Joe

Hi Joe,
You can install the foam on the inside. You just need to be certain to seal
the penetrations for electrical and openings. If any condensation does
form, it usually can dry to the exterior, but it is critical to try to seal
it well.
Studding up a new wall and insulating it with fiberglass is not near as
effective. If you want to stud it up and install the foam, that is okay,
too, as long as you seal it well.
Insulating the basement walls is a good idea on a house that is already
properly insulated.
You can usually save a couple hundred gallons in the average house.
I would suggest checking with friends and the phone book to get some
contractors. It is critical to check references.
Tom,

Tom,
I used to work for Penquis Cap and I will call them for a heat loss test.
I think it would be important to see how I stan right now.
Couple more questions. Please indulge. What type of foam is recommended
for the interior walls? Interior of foundation? What is the R value of the
foam? Do I need to insualte all the way down the foundation?
I was thinking of putting up 1.5 or 2 " of foam and then stud up new walls
with 2X3's in front of it with foam in the cavities (move the wiring since
it comes up thru the floor). It may be simpler to do 2x4 with 3.5 inches
of foam in the cavity.
Is this over kill and will I need to install a fresh air exchanger. I have
heard horror stories with people that have installed a poly vapor barrier
behind the sheetrock. Mold buildup and the tape falling off the drywall
because of moisture. I have also read articles that discourage insulating
the interior of foundations if the exterior is not insualted. Some claim
insualtion will keep the foundation colder in turn allow water to freeze
and expand causing cracks.
As a side note, I enjoy your columns,radio and tv shows. Many of my
undergrad classes were in environmental studies. Urban planning and
sustainable design systems. It is unbelievable to me that people have not
seen the writing on the wall for years. 5 dollar gas may hurt but it may
put us on the road to attempt to be sustainable.
Thanks,
Joe

Hi Joe,
You can use polystyrene foam or polyisocyanurate on the inside. The R value
should be at least R-14. More is better, especially insulating above grade.
I would consider insulating the entire wall, but the above grade area is
most critical.
You can also use spray foam, which is more expensive.
Your plan for studding up the wall in front of the foam is fine. Put
plastic on the wall first, then the foam and then the stud wall.
I don't think you need an air to air heat exchanger for insulating your
basement.
If the basement wall is in good shape, the likelihood of freezing damage is
minimal.
Just keep an eye on the exposed part of the exterior. There should not be
any catastrophic failures, but rather slow, small cracks that might show
up. These can be dealt with IF they occur.
Tom