UK double garage dimensions: two cars, or one car and a workshop

A double garage is a decision, not a size

A single garage asks one question: does the car fit. A double garage asks a better one: what is the second bay for. Plenty of British double garages have never held two cars, and plenty that do hold two cars have owners who would rather they held one car and a workshop. The size of the building matters less than that decision, because the layout for two cars and the layout for one car plus a room share almost nothing.

As with singles, there is no published standard for a double. Some are two single garages built side by side and knocked into one; some were drawn as a double from the start and are wider; some are a single-and-a-half that will take two small cars with the mirrors folded and nothing else. The quoted sizes online describe none of these reliably. Measure yours, and measure it as two bays rather than one room, because the middle of a double garage is rarely as clear as it looks.

Two doors or one, and why it changes everything

A double garage with two single up-and-over doors has a pier between them, and that pier runs the full height of the front wall. It splits the front of the garage into two openings that are each narrower than the bay behind them, so a car has to line up with its door rather than with the space. Each door also has its own track and mechanism on the pier side, which means the middle of the garage carries two sets of ironwork at car-door height.

A single wide door removes the pier and gives one open span, which is far easier to park in. The cost is overhead: the door mechanism and the door itself, when open, run across the whole width of the ceiling near the front, so the whole front of the garage loses height rather than just the two sides. Neither layout is better; they steal space from different places, and the measuring method has to follow which one you have.

How to measure a double garage

Take the measurements with both doors fully up, because the open door is the largest obstruction in the building. Treat each bay as its own garage: measure it at its narrowest clear point, to the thing that sticks out furthest rather than to the wall, and record the two bays separately. Then measure the whole, because the whole is what a workshop layout uses.

1. 1Doors fully upBoth of them, or the single wide one. Every measurement below assumes the door is open, since that is when a car is moving and when the door mechanism is in the way.
2. 2Width of each openingFor a two-door garage, measure the clear width of each door opening at car-door height, between the tracks. A car has to pass through this before it reaches the bay, so the opening is often the limiting width rather than the bay itself.
3. 3Width of each bayWalk the length of each bay with the tape at car-door height and record the narrowest point, measuring to obstructions rather than walls. The consumer unit, the boiler and any pier count. Do this for both bays even if they look identical; they rarely are.
4. 4Total clear widthNow the full internal width at the narrowest point, across both bays. This is the number a single-car-plus-workshop layout uses, since that layout ignores the split.
5. 5Depth and heightClear depth from the inside of the open door to the back wall or whatever is fixed to it, and height under the open door and under the lowest fixed thing further back. In a two-door garage check both sides; the doors can sit at different heights when open.
6. 6The carsLength, width with mirrors folded and out, and the door swing you need to get out. For two cars, measure both, and note which side each driver’s door is on when parked; two driver’s doors facing the same gap is a common mistake.

Two cars, or one car and a workshop

With two cars in, the arithmetic is the single-garage sum twice over, and the gap in the middle has to serve two doors. Subtract both cars from the total clear width, then split what is left three ways: outside wall to first car, between the cars, second car to outside wall. The middle gap has to let at least one person out, and if both driver’s doors face it, it has to let two out in turn. Floor-level storage in a two-car double garage is whatever survives that split, which is usually the back wall and nothing else.

With one car in, the second bay stops being a parking space and becomes a room. That changes what counts as clearance: the car now needs to get out past whatever is in the second bay, but the second bay needs no car clearance at all. A bench along the outside wall of the empty bay, shelving on the back wall, and the shared middle as the walkway is the layout most people end up with, and it works because nothing in it fights the car door.

Where storage goes when both cars are in

The middle strip between the two cars is the walkway and the door-swing zone, and anything that lives there will be walked into or hit by a door within the week. Keep it empty from floor to head height. The two outside walls are available above bonnet height, which is where hooks for long things and shallow shelving belong. The back wall is the one place where floor-standing shelving fits, and only if the depth sum says you can reach it with the cars in.

A two-door garage has one extra asset that a wide-door garage does not: the pier between the doors. Its inside face is a strip of solid wall at the front of the garage, in the middle, that no car door reaches. It is the natural place for the things you grab on the way out, on hooks fixed into the masonry.

What a double garage does not solve is height. Both layouts lose the front of the ceiling to the open door, and in a two-door garage the two doors may sit at different heights when up. Measure under each before assuming anything tall or ceiling-hung will fit near the front. The back of the garage, clear of both doors, is where the full joist height is, and it is where anything tall belongs.