Adding more insulation to an attic with R-38 fiberglass
I have a 2200 SF raised ranch built in 1983, with another 1000 SF finished in the portion of the basement with 4′ stem walls. The rest of the basement is unfinished. The heat is electric radiant throughout; on the main floor the heating cables are laid on top of the ceiling drywall. I’ve just moved in and the house was vacant for the previous two years, so I have no idea what to expect for heating bills.
The house is well built and insulated for its age, and the windows are mostly oriented to the south, so there is some heat gain in winter. There is R-38 fiberglass (two layers of R-19, with the bottom paper faced and in contact with the ceiling drywall; the top layer is unfaced) in the ceilings, insulated 2×6 exterior walls, and single-pane Pella casement windows with gasketed interior storm windows. The entire floor between the main floor and the basement is insulated to R-19. The house is not drafty at all, though there are many can lights. Replacing them with airtight cans and then getting a blower door test is my next step.
The house is in central Pennsylvania (5A climate zone.) Electric is about 9¢/kWh. Propane is available, but natural gas is not.
My question is this: I had an insulation contractor come in this week. He looked at the attic and said that to install blown-in cellulose insulation, all of the fiberglass would have to be removed, because if it wasn’t it would get compressed from the weight of the new cellulose. He also said that it would not be cost-effective to install more insulation of any sort, since the house already has R-38.
Is this really the case? Are there any other energy-conserving strategies I might consider? A geothermal heating system would be nice but it’s out of my reach at the moment.
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