Converting a garage into a home office

Sitting still in a garage is the hard case

A workshop forgives a cold garage because you move in it. An office does not. You sit still for hours in a room built to keep a car dry, with single-skin walls that have no insulation, a slab that pulls heat out through your feet, and an up-and-over door that leaks air round every edge. The furniture is the easy part and the last part. The hard part is making the room somewhere a person can sit through February, and that is why a garage office is usually more than a DIY job.

It is also, for most people, a decision about the whole garage. A bike, the lawnmower and the Christmas boxes still need to live somewhere, and if they stay in the room with the desk they need to be on the wall. The thread through every garage project runs through this one too: the floor is scarce, the walls are free, and an office that shares a garage only works if the garage half gets tidied onto its walls first.

Check before you spend

Turning a garage into a room you occupy commonly brings in insulation, damp-proofing, new power, ventilation, and sometimes planning permission or building control. Whether it does depends on the garage, the house and what it was built under, and none of that can be answered by a guide. Contact your local authority, describe what you intend, and get an answer before ordering anything. A detached garage, an attached one and one under the bedrooms can each get a different reply.

Two more calls. Tell your home insurer that the garage is now a room with a computer in it, because a policy priced for a garage may not cover an office. And read your lease or tenancy if you have one, because some forbid changing the use of a garage or fixing to its walls, and some properties carry a planning condition that the garage stays as parking. Reversible choices — freestanding shelving, a floor that clicks together, a desk that is furniture — are the safe default until you know.

Noise is the check people skip. An integral garage shares a wall with the house and often sits under a bedroom, so calls carry one way and the washing machine carries the other. A detached garage has the opposite problem: the road, the neighbour's mower and the rain on a single-skin roof arrive unfiltered. Sit in the empty garage for an hour on a weekday with a laptop before deciding, because that hour tells you more about whether the office will work than any drawing does.

Damp, then walls and power, then floor

The sequence is the same as every other garage project and it is ignored more often here, because an office feels like decorating. Damp gets found and fixed while the room is empty. Insulation, power and ventilation go in while the walls are bare, because a cable chased behind a finished wall is a wall coming down. Storage and anything fixed to the wall goes up next, and the floor goes down last, because everything above it drops dust and screws.

To check for damp, tape a square of polythene flat to the slab for a day or two; if it mists underneath or the concrete darkens, moisture is rising through it, and a carpet laid on that slab will smell within a season. Look at the walls after heavy rain. Insulating over a damp wall traps the water and makes it worse, which is the specific way garage offices go wrong, and it is invisible until it smells.

Half an office is often the right answer

Many garage offices are the back half of the garage, with the front half kept for storage or even the car, and a partition between them. It keeps the up-and-over door and the parking, it halves the area you have to make warm, and it puts the desk at the end furthest from the draught. The partition wall is also the wall that takes the storage for the garage half, so the front stays a garage that works rather than a corridor of boxes.

The trade is light. The back of a garage is the darkest part of a dark room, so a half conversion usually means a window in the back or side wall, which is itself something to ask the local authority about. Plan the desk against the wall that will get the window, and plan the power for that wall before the partition goes in, because the partition is the thing you least want to open up again.

Storage off the floor so the desk is not the store

A desk in a garage becomes the shelf for everything that has no home, which is how the office stops being one. Give the garage half its own storage before the desk arrives: a freestanding boltless shelving unit stands against masonry you may not drill and takes the boxes, the tins and the bulk of what used to be on the floor; steel hooks above shoulder height take the bike, the ladder and the hose. The office half then needs only a shallow shelf or two.

Floor tiles that click together over the slab suit the garage half and a rented garage in particular, because they lift again. They are not a substitute for insulation under the office half, and a slab that failed the damp test needs the damp dealt with before anything goes over it. A silent clock is a small thing that matters in a hard, echoing room; a ticking one in a concrete box is louder than you think.