Without a garage, every option removes some of the weather and leaves the rest. A cover takes the sun and the bird droppings. A carport or a tent takes the rain. A bubble takes the wind too. None of them is a dry building, and damp does most of the harm to a car that stands still. This guide says what each option does, what it leaves, and when it is enough.
For a car that is driven every week, yes. For a car that will stand for months, outside is the hardest place to keep it well, and the reason is the air rather than the cold. London's daily high relative humidity averages about 92% across the year, and on a clear winter night the air near the ground often reaches saturation, which is what dew and frost are. The Canadian Conservation Institute, whose guidance museums use for storing metal objects, says the layer of water on a metal surface grows rapidly above 75% relative humidity, and that leather and other protein-rich surfaces can show mould in about 100 days at 70%, and 10 days at 80%.
Sun does the rest. Continental says UV and heat damage rubber and tells owners to keep tyres out of direct sunlight. Bird droppings mark paint, and Autoglym's research found the cause is the lacquer softening in sunlight, then cooling and hardening around the dried dropping, rather than acid. Animals arrive in winter: the RAC reported in October 2025 that rodent damage claims rose 28% in 2024, with an average repair bill of £2,494, and that the damage is more common in the winter months, when animals look for shelter.
It solves one problem and can create another. A cover keeps the sun, sap and droppings off the paint. It does not keep the car dry. Jesse Crosse, writing for Hagerty UK, puts it plainly: outdoor covers can trap condensation, which is highly undesirable, and vented covers help only a little because more of the cover lies flat against the paint. He ended up leaving a couple of his own cars uncovered so that air could move around them.
If you do cover a car outside, use a breathable cover made for the car, strapped under the body, and put it on a clean car. Our winter storage guide explains why grit under a cover that moves even slightly ends up as fine scratches across every panel. Never use a plastic or waterproof sheet; it holds the moisture against the paint. Our own view is that on a windy site a cover that lifts and flaps does more harm than no cover at all.
Yes, for everything that falls from above: rain, frost, sun, sap and droppings. It does nothing for what is in the air. The air under a carport is the outside air, at the outside humidity, and wind still carries rain and grit under the roof. A carport suits a car that is used every week and wants to be kept clean. On its own it is not a winter lay-up.
A Carcoon is an enclosed cover with a blower that keeps air moving inside it. The company says its aim is to isolate the car from the constantly changing temperature and humidity of the ambient environment and to stabilise conditions by removing excess moisture, fuel and oil vapour, with air drawn through activated carbon filters. Carcoon also sells indoor versions for use inside a garage. The outdoor version is a double skin, which Carcoon describes as a bubble within a bubble with an insulating air gap, so that the outer skin takes the rain and the ice and the inner skin stays dry and ice free.
The blower runs continuously, according to Dancover, which sells them, so the bubble needs power at the parking spot. Carcoon describes the air inside as filtered and circulated rather than giving a humidity figure, so treat it as a dry, filtered pocket of moving air rather than a dehumidified room: put the car in clean and completely dry, and keep a cheap hygrometer inside so you know what the air is doing. A bubble on a driveway is visible from the road, which is worth weighing against the protection it gives.
A tent garage is a roof and walls, and nothing more. Dancover, which sells them, states that temperature changes and moisture in the air can cause dew or condensation to appear outside and inside the shelter, that this is normal, and that the ground sheet is there to keep moisture, dirt and dust off the floor. The frame is steel and the skin is PVC; neither is insulated.
Why does a cold roof drip? The dew point is the temperature to which air must be cooled to reach saturation. A thin skin, whether PVC, steel or glass, loses heat to a clear night sky faster than the air beneath it, so it drops below the dew point of that air first, and the moisture in the air condenses on it. The steel container trade calls the result container rain. The same physics applies to a tent roof and to the underside of a car cover.
So a tent keeps the rain, sun and most of the wind off a car, and that is worth having for an autumn or for a car in regular use. For a winter lay-up, add a breathable cover for the drips, a battery conditioner if there is power, anchor the frame properly, and check inside after cold clear nights. Our self storage guide covers the container version of the same problem.
Yes. Marketplaces such as Stashbee list private garages and lock-ups. What you get is a roof, four walls and a lock, which deals with rain, sun and wind and keeps the car out of sight. The same applies to a farmer's barn, which is often cheaper and often damp and shared with wildlife, and to a space in a residents' or underground car park, which is dry overhead but open to whatever air and people move through it. The humidity is whatever the building sits at. Continental's warning that garages, sheds and attics undergo a range of temperatures, precipitation and humidity applies to a rented one as much as your own. Our self storage guide explains why a pre-cast concrete garage sweats in cold weather where a brick one does not, and why a dehumidifier does more than a heater.
Before you pay, ask four things: whether there is power for a battery conditioner and a dehumidifier; whether the garage is brick or pre-cast concrete; who insures the car while it is there, which our insurance post covers; and whether anything edible is kept in the building. The RAC singles out pet food stored in garages as a draw for rats and mice, and advises checking any car that has stood for a week or more.
When the car will stand for more than a few weeks, when it is worth more than the kit you would otherwise buy, or when there is no safe hard standing at home. The difference is the air. Good car storage holds the whole building at roughly 50 to 55% relative humidity, at or under the 55% line where the Canadian Conservation Institute says mould growth stops and well below the 75% where metal corrodes quickly, and it does so without heating, because warm damp air only condenses on cold metal later. The car sits under a breathable cover on a battery conditioner and is looked at every day. Our facility guide lists the questions that sort a real storage building from a locked shed.
Only if it stays taxed and insured. A SORN car must be kept off the public road, on a drive, in a garage or on private land. GOV.UK sets no national time limit on a taxed, insured car parked on a street, but councils decide what counts as abandoned, and flat tyres are one of the signs they look for.
For rain, sun and wind, yes. For security, no, because it is not a locked building. For damp, partly: it circulates filtered air around a car that went in dry, and the maker gives no humidity figure to compare with a dried building.
No. A dehumidifier only lowers the humidity of air it can keep hold of. In an open or draughty space it dries the outside world. It works in a sealed garage, which is why our self storage guide pairs it with insulation and draught-proofing.
On a sheltered spot, with a breathable tailored cover on a clean car, yes. On an exposed spot where the cover moves, no. Plastic sheeting is worse than nothing anywhere.
Henry's Car Barn has stored cars since 1984, from sites in Warwickshire, London, Hampshire and West Sussex, plus a fifth at Thruxton from November 2026. Every car is inspected on arrival, air dried for 24 hours and photographed, then put away with the handbrake off, under a breathable cover, on a battery conditioner. The sites are inspected daily and the conditioners are checked weekly. We collect from your door with our own transporter, and can move cars across the UK and Europe.
