We're doing a major renovation on our 1970s ranch and our contractor is pushing us toward closed-cell spray foam for the attic and walls. It's like $3-4 per square foot compared to maybe $0.50 for fiberglass batts. Everyone says it's better for air sealing but I'm wondering if the price difference actually makes sense for a mid-range renovation budget.
Spray foam is genuinely better at air sealing and moisture control, which matters more in older homes where drafts and thermal bridges eat up a lot of energy costs - so the difference isn't just marketing. That said, the payback period on that price gap is usually pretty long (we're talking years), and if your renovation budget is tight, you could get most of the benefit by doing spray foam in just the attic and rim joists (where air leakage is worst) and sticking with batts or blown-in cellulose elsewhere. The real question is whether you're planning to stay in the house long enough to recoup it, and how much the improved comfort and air quality matter to you beyond pure ROI.
the real question is whether you'll actually stay in the house long enough to break even on that premium. for a 1970s ranch you're absolutely right that air sealing matters way more than in newer builds, and closed-cell does it better than batts. but here's what gets skipped over: spray foam can trap moisture against the wood framing if the vapor barrier setup is wrong, which turns into rot over time. get a second opinion from someone who isn't selling you the foam, and do the math on your specific energy costs and how many years you're planning to be there. if you're staying 15+ years and energy costs keep climbing, it probably pencils out; if you might sell in five years, stick with batts and pocket the savings.
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