Open-Cell Spray Foam

Open-cell spray foam is applied as a liquid, expanding 100 times its volume and curing within seconds to fill every crack and gap. Compared with traditional insulation, it can provide up to 50% energy savings thanks to its inherent, near-perfect air seal.

This technology offers the best R-value/cost ratio, with high energy savings resulting from very low ACH (air changes per hour) ratings. Open-cell foam performs as an effective air barrier but does not qualify as a vapour barrier.

Benefits

• Dramatic savings in heating & cooling costs
• Creates a seamless air barrier
• Helps eliminate the growth of mould
• Breathes very slowly while still sealing air
• Excellent noise reduction due to its softness
• Lowest cost among the different foam types

Where Open-Cell Makes Sense

Open-cell foam is the lighter product, around half a pound per cubic foot, with a softer, more flexible structure whose cells are open to one another. It expands more aggressively than closed-cell, which makes it very good at filling deep or awkward cavities, and its open structure absorbs sound far more effectively.

• Interior partition walls where sound control matters
• Home theatres, media rooms and offices
• Vented attic assemblies with adequate depth
• Deep wall cavities where expansion is an advantage
• Projects where budget per square foot is the constraint

Vapour Permeable by Design

Unlike closed-cell, open-cell foam allows vapour to pass through it. In the right assembly that is a feature rather than a limitation, because it lets the structure dry in one direction and can reveal a roof leak rather than hiding it. In the wrong assembly, particularly below grade, it is the reason we would specify closed-cell instead.

The Honest Comparison

Open-cell delivers roughly half the R-value per inch of closed-cell, so it needs greater depth for the same thermal performance. Where you have that depth, it is an excellent and more economical choice. Where you do not, closed-cell is the answer. Neither is universally better.