Cellulose is the main alternative to spray foam in Alberta retrofits, and there are plenty of jobs where it is the better choice. We would rather say that plainly than pretend foam wins everywhere.
What cellulose is
Recycled paper fibre, treated with borate for fire and pest resistance, blown in as loose fill. It is normally installed either loose on an attic floor or dense-packed into an enclosed cavity.
It is inexpensive per unit of R-value, has good environmental credentials, and installs quickly.
What separates them
Air sealing. This is the real dividing line. Spray foam is an air barrier - it adheres and closes the path. Cellulose is not; it resists air movement when dense-packed, but it does not seal. If air leakage is your problem, cellulose alone will not solve it.
Water. Cellulose absorbs water and loses its performance when wet. It can dry out and recover in an assembly that dries well, but it does not tolerate a location where bulk water is a credible risk. Closed-cell foam at adequate depth does.
R-value per inch. Foam, particularly closed-cell, delivers considerably more in the same depth. Where the cavity is shallow or you cannot build outward, that can settle it on its own.
Cost. Cellulose is meaningfully cheaper for the same area. In a big, open, dry, accessible space that gap is large.
Settling. Loose-fill cellulose settles over time in a vertical cavity, which can leave a gap at the top. Dense-packing addresses it. Foam does not settle.
Reversibility. Cellulose can be removed and replaced without much drama. Closed-cell foam bonds hard and is genuinely difficult to remove.
Where cellulose is the better buy
An open, accessible attic with plenty of headroom, where the penetrations have been properly air sealed first. Seal the leaks, then bury them under a deep layer of cheap insulation. This is the classic case where paying for foam across the whole attic floor is spending money on performance the assembly cannot use.
Large dry wall cavities in a well-understood assembly, where budget matters and there is no moisture concern.
When the budget is the constraint and the alternative is doing nothing. More R-value now beats perfect R-value never.
Where foam is worth the premium
Rim joists, where the whole point is sealing an irregular, penetrated cavity that no loose fill will close.
Crawl spaces and basements, where moisture and air movement both need answering at once.
Roof decks and cathedral ceilings, where there is no room for depth and no ventilation space.
Metal buildings, where the requirement is stopping condensation on cold steel, which loose fill cannot do.
Anywhere bulk water is plausible.
The combination that often wins
You do not have to choose one for the whole house.
A common and sensible Alberta approach: spray foam where sealing matters, cellulose where only depth matters. Foam the rim joist and air seal the attic penetrations; then blow cellulose across the attic floor to depth.
You get the sealing where it counts and the cheap R-value everywhere else. Anyone who insists the entire building must be foamed is selling rather than assessing.
How to decide
Ask what the problem actually is. If it is draughts, cold spots, condensation or moisture, you need sealing and foam is likely part of the answer. If it is simply not enough insulation in an accessible, dry, already-sealed space, cellulose will do it for less.
Want an honest read on which yours is? Get a quote.
Related: spray foam vs batt vs blown-in - spray foam vs fibreglass - when not to use spray foam - is spray foam worth it