Is spray foam insulation the best choice for an old house?

In renovating an old house, is spray foam insulation the way to go? And which type of spray foam insulation - open cell or closed cell?

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    The slats in the walls of the farmhouse suggest how drafty this building must have been during cold New England winters.Salvaged doors and wood are being saved for the new construction. Now the renovation decision is: What type of insulation to choose?
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Want to get confused? Listen to several contractors tell you the best way to insulate your drafty old house.

That’s exactly what I did last week. And after puzzling over how people could come to such widely varying conclusions, I have now emerged from the experience better versed on spray foam technology than I ever thought possible – and am almost, but not quite, ready to make a decision.

Early on I opted against traditional fiberglass batting (pink or yellow) because, from my earliest research, I thought that it was clearly not the best choice for us, even though it’s the least expensive in the short term.

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The primary reason has to do with our decision to put in geothermal heating. For it to work optimally, a house has to be as airtight and insulated as possible. With a 1902 farmhouse with plenty of nooks, crannies and cracks, fiberglass batting just won’t do the trick, according to the various experts I spoke with.

So we knew we wanted to put in spray foam insulation – and a good, green spray foam at that.

“Spray foam gives you an air barrier which is our secret weapon – it doesn’t allow for any air movement like fibrous insulations,” says Ned Williams of Connecticut Spray Foam Industries in East Haven, Conn. “Air infiltration is really becoming enemy No. 1 in the insulation battle, while R-value is turning out not to be the simple savior.”

OK, once we decided to use foam to seal up our leaky house, the next question was whether to choose open-cell or closed-cell foam?

Open cell is flexible, made up of what are essentially billions of minuscule broken bubbles. It’s water permeable and less expensive than closed cell. But it doesn’t produce as high an R-Value.

Closed cell is more solid, like a foam board. That makes it a bit brittle, but also gives it a higher R-value.

The contractors from both Anchor Insulation and Connecticut Spray Foam Industries recommended open-cell insulation for most of the house – in part because the closed-cell foams create a vapor barrier and are impermeable to water.

“If you have a leak in the roof – and eventually they all leak – where is the water going to go?” says Mr. Williams. “If it’s a two-pound, closed-cell vapor barrier kind of foam, the leak’s going to stop at the foam and that water will be trapped in the system. If it’s an open cell half pound system that water’s going to drip right through.”

Ever hear of mold? Preventing it sounds like a good reason to us to go for the open-cell foam.

Another problem with closed-cell insulation, according to Marek Ropiak of Anchor is that it's solid, like a rock.

“With open cell, the house is tighter and quieter. Closed cell is very hard, almost like concrete,” says Mr. Ropiak. “If you use it, you’re going to get more echo. It’s always nice to have the house quiet.”

Knowing my interest in going green, both of these contractors also recommended I consider Icynene, a spray foam made up of, among other things, recycled bottles and castor oil.

I was almost convinced, and then John Taconis of US Insulation came to give his estimate. He recommended closed-cell foam for certain areas of the house and a hybrid system of closed-cell foam backed up with batts of the inexpensive fiberglass. Closed cell has a much higher R-Value than open cell, he argues.

“Open cell on a two-by-four has the same R-value as fiberglass,” says Mr. Taconis. “Why not use a hybrid system, foam to seal the system and fiberglass bat for R-value? Once you seal a leak, it no longer leaks. Seal it 10 more times, and it doesn’t do you any good if you seal right the first time.”

He recommended that we go on US Insulation’s website and look at a video to see how the hybrid system called Air Tight System and made by Guardian works.

Then, to be fair in the decision-making process, I also looked up a video on how Icyene is applied.

There was one thing all three contractors agreed on, though. In the basement, to insulate the floor of the house, they’d all recommend fiberglass batting.

The reason? Building codes require all spray foam insulation to be enclosed in areas where people spend time. So, in addition to the spray foam, which is already two to three times the cost of the fiberglass batting, we’d have to sheetrock the basement ceiling.

So much for sticking to my initial decisions.

Next: The prices and what we finally decided to do.

Editor's note: Alexandra Marks will be blogging twice a week about her green and budget-friendly restoration of a 1902 farmhouse in Connecticut. See a photo gallery of the early days of the project by clicking here. You can read all she's written about the project so far by clicking here and then looking for Sheep Dog Hollow under Topics on the right side of the page.

You'll find numerous articles about the environment at the Monitor’s main environment page. Also, check out our Bright Green blog archive and our RSS feed.

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