Replies

1. 
   DanH | Oct 05, 2009 03:08am | #1

   I think most here prefer cellulose for unfinished attics -- unless you're willing to cough up the coin for sprayed foam.

   (And there's no problem with placing cellulose over existing fiberglass batts.)

   As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
2. 
   mike_maines | Oct 05, 2009 04:24am | #2

   The most important thing to do is air sealing, then install a total of R38 to R49 insulation.  Fiberglass insulates well in perfect conditions, which are hard to achieve.  Cellulose or closed cell foam are the best ways to get quality insulation, but cellulose is cheaper and performs almost as well as foam in most cases. 

   That's the gist of it anyway. 

   As for your furnace, there are any number of ways to make a new one solar hot water compatable.  Do you really have a furnace (hot air) or a boiler (radiators)?  How do currently heat your domestic water? 

   If you are in the Portland to Brunswick area I can recommend insulation and heating contractors for you, if you're interested. 

3. 
   WayneL5 | Oct 05, 2009 06:06am | #3

   Sealing up open holes, such as wiring or piping holes, then adding blown in cellulose over top of everything is an economical and satisfactory solution.  There is no need to remove existing fiberglass.  You'd also need to avoid covering can lights that are not rated to be covered with insulation.  Or take them out, they are a lousy idea when penetrating the heating envelope anyway.  And barriers are needed so soffit ventilation would not be blocked.

   Be sure to size the boiler by heat loss calculations.  You'll need a smaller boiler after insulating.  If you install a boiler that's too large it won't run efficiently and you'll waste money and be less comfortable.  Don't let any contractor size the boiler by rules of thumb.

4. 
   thorn | Oct 05, 2009 12:15pm | #4

   Dan, Mike, and Wayne -

   Thanks for replying, the information supplied was helpful.  Cellulose sounds like the way to go.

   Currently the house has gable end vents, and we were planning to have a ridge vent and continuous soffit vents installed along with this effort.  We also need to take care of the one bathroom fan venting into the attic.

   The domestic hot water and cast iron radiators are supplied by a oil burner, circa 1968.   We are going to replace it with something more efficient, and have been thinking of combining the solar hot water to it.

   Mike, please send along your contacts, as we will be in the Portland area.

   Thanks,

   David

1. 
   mike_maines | Oct 05, 2009 03:50pm | #5

   David, I sent you some contacts.  Our heating guy usually recommends installing a high efficiency variable speed boiler, with a "Superstore" dual coil tank that can be heated from the boiler or the solar panels.  The tank is expensive, but the system works with or without panels so you can phase the work if you want.  Natural gas is available in some areas here, but propane is more common.  Either are much cleaner and lower maintenance than oil.