Home>Discussions>INSULATION & HVAC>no insulation beneath back of house addition?
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no insulation beneath back of house addition?


There is an addition in the back of our 1928 house, we think added several decades ago, maybe 1950s. It was an amateur addition built on top of an existing open porch. The porch was never jacked up. It was added right on the natural slope of the porch. It now slopes about 3" off the level of the house. It is part of our eat in kitchen. Anyway, our heating bills during the winter have reached over $600 a month (with the thermostat at 64and a furnace installed in 2006) as we realized that beneath that addition, there is no insulation whatsoever. There is also really no foundation, just the original porch footers, and where there were openings beneath the porch, they simple put in some boards, that have been caulked a hundred times around, and are now decaying and splintering at the weight of the sinking footers, and offer no insualation whatsoever. It's like having a basement beneath that part of the house that has a bunch of wide open windows.

So, my question is what can be done...and at the least expense? Can we just leave the footers alone, since jacking up the back of the house 3" is not an option?...can't move the roof that much/ can't move the 2nd floor porch that sits on top of it all. simply just can't do it. maybe we can just brace the footers.

Can we just remove the boards in any case and fill in with masonry or some type of insulating concrete? This my only idea. Any reccomendations would be much appreciated.

Russell DuPree
Re: no insulation beneath back of house addition?

I would recommend getting under the addition and insulating with fiberglass, vapor barrier up, and covering tightly with plywood or other wood sheathing so no rodents can get in, perhaps even providing some outside-air vents through the skirting, leaving the skirting in place. Cover the floor of the crawl space with a non-degradable plastic vapor barrier, and add shallow footings under the jacked up carrying beams as you described. Russ DuPree, Freeport, Maine.

Re: no insulation beneath back of house addition?

All good ideas. I had not thought of a vapor barrier. That's a great idea. So far we're thinking pretty much what you said with new plywood sheeting installed from inside and outside the open spaces, with some sort of sealant around the outside boards. A vapor barrier installed over top of that from the inside along the walls, ceiling, and floor of the crawlspace. Then, fiberglass insulation all along the walls and ceiling. Then, from the outside for added insulation and moisture protection, we may have some vinyl siding installed around skirt of the house back there close enough to match our existing color. We also considered a glass block option...or at least installing glass block in the two windows in the basement that lead to the crawlspace. Those are the only two in our basement that are not glass block.

I appreciate your advice!

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