Spray Foam vs Cellulose Insulation — Pros, Cons and Carbon Impact for Homes

Spray Foam vs Cellulose Insulation — Pros, Cons and Carbon Impact for Homes Insulation choice shapes comfort, long-term energy bills, and a home's embodied carbon footprint. This article compares spray foam (closed- and open-cell) with cellulose insulation across R-value, air-sealing, cost, DIY feasibility, and lifecycle climate impact to help a budget-conscious DIY self-builder choose the right approach for 2x4 walls, attics, and small roofs. TL;DR: - Closed-cell spray foam: ~R-6 to R-7 per inch, excellent air and moisture barrier, highest installed cost and highest embodied-GWP risk depending on blowing agent (use HFO formulations if available). - Open-cell spray foam: ~R-3.5 per inch, strong air-seal and acoustic benefits, lower material density and cost than closed-cell but needs greater thickness for the same R-value. - Cellulose (dense-pack/blown): ~R-3.2–R-3.8 per inch, lowest embodied carbon and cost for many installs, DIY-friendly for attics; requires separate air-sealing stra...