Vinyl flooring is not recommended for outdoor use or for areas that are exposed to the elements. It’s designed for indoor use. Here’s why and some guidelines on unheated areas:

Outdoors (Patios, Decks, etc.):

• UV Damage: While vinyl flooring has some UV resistance, constant direct sunlight and weather will cause it to fade and deteriorate over time​. The wear layer and the materials can break down with prolonged UV exposure, leading to brittleness or discoloration.

• Temperature Extremes: Outdoor temperatures can get far higher and lower than indoor. Vinyl planks can expand and contract significantly with big temperature swings. In a floating installation, this could cause planks to warp or click apart. In glue-down, the adhesive could fail or the vinyl could crack in extreme cold.

• Moisture: Although vinyl itself is waterproof, outdoors you have rain, snow, etc., which can seep underneath and cause mold on the substrate or just make the installation unsound. Also, water sitting on vinyl outdoors could make it very slippery.

• Warranty Violation: Pretty much all vinyl flooring manufacturers will void the warranty if the product is used outdoors. They specifically advise against external use.

So, a covered enclosed porch is okay if it’s basically indoors, but open outdoor patios or decks – vinyl flooring is not suitable there. Use products specifically made for outdoor (like deck tiles, outdoor carpet, etc.) instead.

Unheated Areas (e.g., sheds, sunrooms, seasonal cabins, garages):
This is a bit more nuanced:

• For unheated sunrooms or three-season rooms: Many people do install vinyl plank in sunrooms. If the room is enclosed and protected from rain but just isn’t heated or cooled year-round, vinyl can work as long as the temperature range isn’t extreme beyond the product’s specifications. Some rigid core vinyls (SPC) can handle a wider range of temps (often down to about 50°F and up to about 100°F or more). But if that sunroom goes below freezing in winter and very hot in summer, you might have expansion/contraction issues. Check the product guidelines; some say “install in climate-controlled environments only.” There are a few vinyl flooring lines marketed for sunrooms that can handle more fluctuation.

• For sheds or garages: A typical garage is not temperature controlled, and also has heavy vehicles, etc. Vinyl is generally not used in garages with vehicles because hot tires can damage it (and weight). In a shed, cold winters could make the planks brittle and they might contract. Also, lots of dirt and outdoor grime might scratch it up. If it’s a workspace shed that you occasionally heat and you want a nicer floor, some people have done it, but again, it’s out of intended spec. For garages, better to use epoxy or garage-specific flooring.

• Seasonal cabins: If you have a cabin that isn’t heated in the winter, vinyl might shrink in the extreme cold. But interestingly, many people do use LVP in cabins because of water resistance. They often just accept that there might be some gapping in winter which closes in summer. If the product doesn’t explicitly forbid it, it could be an option, but it’s somewhat at your own risk in terms of stability. An alternative for extreme temp areas is something like rubber flooring or certain tiles that handle freeze/thaw, or just be prepared for possibly having to fix some planks later.

Better safe than sorry: As a rule, keep vinyl flooring in enclosed, climate-stable environments. If you need flooring for an area that’s exposed to weather or significant temperature swings, look for materials designed for that (like outdoor-rated tiles, composite deck material, concrete, etc.).

So, to directly answer: Vinyl flooring is not suitable for outdoor exposed use, and for unheated areas it’s generally not recommended unless the product explicitly allows it or the conditions are mild. Always consult the manufacturer guidelines for temperature ranges. Using vinyl outside those parameters could lead to problems and will usually void warranties.