Portable garages and car shelters for a classic car

A portable garage, also sold as a pop up garage, temporary garage, garage tent or car tent garage, is a fabric cover stretched over a metal frame. Hagerty UK describes them as "essentially big tents, with a metal frame and waterproof covering". The Clarke Instant Garage is one widely sold example of the type; its manufacturer states plainly that it is a temporary structure, not a permanent building.

For a classic car without a permanent garage, one can keep off rain, leaves and bird droppings. It does not, on its own, keep a car dry in the sense that matters for long-term storage. That distinction runs through the rest of this guide.

• Tunnel or dome tents on a steel frame: curved hoops of tube joined by connectors, with a one-piece or sectional cover and a door panel at one or both ends. These make up most of the market.
• Apex shelters: a ridged, pitched roof rather than a curved one.
• Heavy duty portable garages: larger frames in galvanised steel with thicker covers, sold for longer-term use and able to be bolted to a concrete base.
• Open carports and outdoor car shelters: a roof with no full walls or door. Hagerty UK notes that a carport keeps off rain and snow but does not seal the car from the elements, so an additional cover may be needed.

Frame materials

Most frames are steel tube. Better models use galvanised steel, which manufacturers present as more resistant to corrosion than plain coated tube. Manufacturers publish tube diameter and wall thickness; examples include 25 mm tube with a 1.0 mm or 1.1 mm wall, and larger 32 x 45 mm oval sections on heavier units. These figures allow like-for-like comparison between models.

Cover materials

• Polyethylene (PE): the lighter, more common cover. Published examples sit at around 300 g/m², with UV protection added.
• PVC: heavier and stiffer. Published examples for PVC garage covers are around 500 g/m².

A heavier cover is not automatically better for a car inside. Neither PE nor PVC breathes, so both collect condensation on the inside face.

Every manufacturer's guidance treats anchoring as essential, and as the owner's responsibility. Clarke warns that serious injury or damage could result if a garage is not securely anchored, and ShelterLogic states that a shelter which is not securely anchored is not covered by its warranty.

• Soft ground: auger pegs, stake pegs or cable anchors driven into the soil, with extra anchors in exposed spots.
• Concrete or tarmac: base plates fixed with ground anchor bolts or expansion bolts.
• Ballast: where pegs cannot go in, weights on the base rails or skirts. Hagerty UK suggests weights if the supports cannot be pegged.
• Skirts: some covers have side skirts that are dug into the soil or weighted with slabs to stop wind getting underneath.

Check anchors and strap tension regularly; manufacturers advise this for any shelter left up for a long period.

Manufacturers are direct about the limits. Clarke says its garage is not designed for high winds or heavy snow. Dancover says its portable garages are not tested for specific snow and wind loads and that the owner is responsible for securing them and clearing snow.

• Wind: put the cover on during a calm day, keep doors closed in windy weather so the cover cannot lift from inside, and choose a sheltered site. If strong winds or a storm are forecast, ShelterLogic and Dancover both advise securing the structure or taking the cover off.
• Snow: brush snow and ice off promptly with a broom or soft tool, from outside. Never push snow off from inside, and never use a rake or shovel, which can puncture the cover. Build-up can cause collapse.
• Warranty exclusions: typical terms exclude damage from poor anchoring, from bad weather or "acts of nature", and in at least one case collapse under snow load.
• Fire: keep naked flames, heaters and stored fuel out of and away from the shelter; the fabric will burn.

Condensation inside a garage tent is normal. Dancover says it does not mean the tent is leaking; Clarke says it forms on the inside of the cover on cool, damp days. Hagerty UK warns that a portable garage will not protect a car from humidity unless power and a dehumidifier are added.

• Ventilate: fresh air through the doorway reduces condensation. Some heavier covers include air vents. Good airflow around a stored car is standard advice from classic insurers and motoring titles alike.
• Never seal a car in damp: make sure the car is completely dry before it goes in, including under the bonnet and in the boot.
• Use a breathable car cover inside: a breathable cover lets moisture escape rather than trapping it against the paint. Clarke itself recommends a secondary lightweight cover on a stored vehicle in winter. Avoid plastic sheeting. See car covers.
• Deal with the ground: a concrete or block-paved base is best. On other surfaces, a groundsheet or membrane cuts moisture rising from the ground; some kits include a PE ground cover for this reason.
• Consider a dehumidifier: with a safe power supply, it brings humidity down. More on this in damp and condensation.

A portable garage left standing in a garden can need planning permission. Government guidance defines a building for permitted development as including "any structure or erection", and portable garage suppliers advise that their products are treated as outbuildings. Under permitted development for outbuildings (Class E), the main limits are:

• Position: not on land forward of the principal elevation, the wall that forms the front of the house.
• Height: single storey; maximum eaves height 2.5 metres; maximum overall height 4 metres with a dual-pitched roof or 3 metres otherwise; no more than 2.5 metres high if within 2 metres of the boundary.
• Coverage: no more than half the land around the original house covered by additions and other buildings.
• Listed buildings: any outbuilding within the curtilage of a listed building needs planning permission.
• Conservation areas and National Parks: outbuildings at the side of a house need permission on designated land. In National Parks, buildings more than 20 metres from the house are limited to 10 square metres in total.
• Removed rights: permitted development may not apply where a planning condition or Article 4 Direction has removed it.

Thornton-le-Dale and Ryedale

Thornton-le-Dale lies in Ryedale, on the edge of the North York Moors National Park, and has a designated conservation area. Depending on the address, the planning authority is either North Yorkshire Council or the North York Moors National Park Authority. Check with the right one before putting up a shelter for the winter. A Lawful Development Certificate can confirm that a proposed structure is lawful, though it is not a replacement for planning permission.

Insurers price cover partly on where the car is kept overnight and expect that to be declared accurately. Tesco Insurance defines a garage as "a locked, enclosed building at your home"; Confused.com describes one as a fully enclosed, lockable space. A fabric shelter with a zip door is unlikely to meet either definition.

• Declare it accurately: give the insurer the real overnight location, and say if it is a tent garage or carport on a drive. Wrong or missing details can lead to a claim being reduced or refused, or the policy cancelled.
• Check garaging conditions: some policies require a locked, secured building overnight. The Financial Ombudsman has upheld a declined claim where the storage described as a locked garage did not meet that standard.

• Airflow enclosure: an enclosure such as a Carcoon runs fans continuously to keep air moving around the car and needs mains power. Its purpose is controlling condensation around the car.
• Car cover alone: cheaper and simpler, but a cover leaves the underside exposed to damp air. See car covers.
• Portable garage plus breathable cover: the shelter takes the weather; the inner cover and ventilation deal with moisture.

For the wider routine of preparing a car for months off the road, see winter lay-up. Any laid-up car also needs protecting from rodents. All storage guides are in the classic car storage hub.

• Measure the car plus working space: allow room to open doors fully and walk round the car.
• Door height for the car: check the published door opening, not just the overall height, against the car's height and any roof rack.
• Frame tube diameter and gauge: compare published tube sizes and wall thickness; galvanised steel resists corrosion better.
• Cover material: check whether it is PE or PVC and the stated g/m² figure.
• Zip doors at both ends: a door at each end allows a through draught for ventilation.
• Anchoring kit: confirm what is included for your ground, whether soil, gravel or concrete, and budget for extra anchors.
• Spare covers available: check that replacement roof and end panels are sold separately.