Garden Rooms
& Outdoor Living

Built in situ rather than dropped in as a kit, expect roughly 1,600 to 2,600 pounds per square metre. A 12 square metre office lands around 19,000 to 31,000, and a 20 square metre gym or studio around 32,000 to 52,000. Adding a shower room pushes it up about 18 percent and making it a full annexe with a kitchen and shower room around 35 percent.

Usually not. Outbuildings are generally permitted development if they are single storey, sit no more than 2.5 metres high within two metres of a boundary, cover no more than half the garden, and are not in front of the house. The rules tighten in conservation areas and for listed buildings. Where it changes is if somebody is going to sleep in it regularly, which can make it a separate dwelling and needs a proper conversation first.

That is the whole point of building one properly. Insulated floor, walls and roof, double glazing, a damp proof membrane under the slab and proper ventilation. The cheap kit sheds sold as garden offices are single skin with a bit of foil, and they are freezing in January and unusable in July. Ours are built like a small house because that is what makes them worth having.

Three to six weeks for an office, gym or studio. A full annexe with a kitchen and shower room runs six to ten weeks because of the drainage and the fit out. Access matters, so if everything has to come through the house rather than down a side gate, that adds time.

Power, always. That is an armoured cable buried at the right depth from your consumer unit, and it is notifiable work that gets certified. Water and drainage only if there is a shower room or kitchen, which is more involved because the waste has to reach an existing drain at the right fall.

It can, particularly a well built insulated one with power that a buyer can see themselves working in. What it will not do is add a bedroom to the listing, because it is not part of the house. If your priority is the valuation rather than the space, a loft conversion usually does more.

Yes, and we build them. It needs a kitchen, a shower room, proper drainage, heating and insulation to a higher standard. Where it needs care is planning, because a self contained unit somebody lives in permanently can be treated as a separate dwelling. We flag that early rather than at the end.

It depends on what is under your garden. Most sit on a reinforced concrete slab with a damp proof membrane and insulation. Where there are trees, made up ground or a high water table, it may need piles or a deeper foundation. We dig a trial hole and look rather than assuming.