Southern Alberta grows and processes more vegetables than anywhere else in the province, and Lethbridge sits in the middle of it. That makes cold storage spray foam insulation in Lethbridge a different conversation from the one in a distribution city, because a great deal of the refrigerated space here is holding produce rather than frozen pallets.
Produce storage is a humidity problem first
A potato or onion store is not run cold and dry. It is run cool and deliberately humid, often well above ninety percent relative humidity, because the crop dries out and loses value otherwise. That is close to the worst condition an envelope can be asked to handle: a large temperature difference and air that is already almost saturated. Any surface inside that assembly that falls to the dew point will wet, and it will keep wetting all season.
Why the vapour control cannot have a seam here
In a dry freezer a small discontinuity is a slow problem. In a high-humidity store it is a fast one. Closed cell spray foam is used in these buildings because it is the insulation and the vapour retarder in one continuous application, so there is no lapped sheet and no taped joint to be the weak point. Applied to a clean, dry surface it follows the structure rather than being fitted to it.
Ventilation and insulation are not alternatives
Crop stores are ventilated on purpose, and it is common to hear that a building that breathes does not need a tight envelope. The opposite is closer to true. Controlled ventilation only works when the air being moved is the air you meant to move; uncontrolled leakage through the shell brings in outside air at outside conditions and lands the moisture wherever the shell is coldest. Sealing the envelope is what makes the ventilation system able to do its job.
Converted farm buildings
A good number of the smaller stores in this region are converted agricultural buildings - a shop or a machine shed with refrigeration added. They were built as shelters and the walls were never detailed for a vapour drive. Foam is generally the only practical way to bring that kind of shell up to a condition where it can hold humidity without rotting the structure behind it.
Cold Storage Spray Foam Insulation Lethbridge: Common Questions
Why is produce storage harder on a building than a freezer? Because it is run humid on purpose. Air near saturation plus a temperature difference means any cold surface inside the assembly wets, and in a crop store that condition lasts for months.
Does a ventilated store still need a sealed envelope? Yes. Ventilation only controls the air you intend to move. Leakage through the shell brings in uncontrolled outside air and puts the moisture where the building is coldest.
Can a machine shed be converted to a crop store? It is done regularly in this area. The shell has to be sound and dry first, and the walls need continuous insulation and vapour control rather than the batt-and-poly detail a shop was built with.
Estimate the thickness with the R-value calculator, then get a free Lethbridge quote. More on Cold Storage Spray Foam Insulation Alberta.