Because the cells are closed and have their own cell walls they are more rigid and trap a large amount of air.
Open cell foam insulation vs closed cell.
Open cell foam is made of irregularly shaped cells that are linked together.
Most open cell foam has a density of about 5 pounds per cubic foot.
This makes for more sturdy products that serve as great insulation.
Closed cell foam can be over three times that with a density of 1 75 pounds per cubic foot or more.
Closed cell foam is made of uniform cells that maintain their own shape.
Because of this the foam expands making it able to cover those hard to reach areas.
Because the cell walls are broken the foam is softer.
A foams r value is its resistance to heat flow or in other words how well they insulate.
Closed cell foam is much denser than open cell foam.
However closed cell will give.
Open cell foam.
Open cell foam insulation is lightweight pliable and easy to work with whereas closed cell foam is rigid and very dense.
Because of this closed cell foam is much more rigid and stable than open cell foam.
Closed cell foam has a higher r value than open cell foam usually about 6 0.
For example if you needed to run new wiring open cell spray foam is going to be much easier to work with because it is so pliable.
At the end of the day open cell spray foam insulation is an affordable option opposed to closed cell.