Garden room cost: what the job involves and who is registered to do it

How garden room cost works

1. Find out whether the base is included. Almost every garden room needs a level, load bearing base: a concrete slab, a screw pile system or a timber frame on pads. Whether that is in the price, and what ground it assumes, is the first question. Sloping gardens, soft ground, tree roots and poor access all change it before anything is delivered.
2. Price getting the building into the garden. A garden room has to reach the back garden. Panels through a side passage, a crane over the house, or a long carry across a lawn are three very different days. Access is the line that most often separates two quotes for the same building and it is decided by your house, not by the supplier.
3. Treat the electrics as a separate certified job. A supply running from the house consumer unit to a detached building is notifiable electrical work with its own requirements for burial depth, protection and earthing arrangements. It is normally not in the building price, it needs a certificate, and it should be quoted by somebody registered rather than added on the day.
4. Decide about drainage before you decide about a toilet. A garden room with a shower or a WC needs foul drainage, which means either a gravity run to the existing system or a pumped one. That is a groundworks job with its own approvals and it roughly doubles the disruption in the garden, so it belongs in the first conversation rather than the last.
5. Check the specification you are actually buying. Wall build up, insulation thickness, glazing units, roof covering and the internal finish vary enormously between suppliers using the same photographs. A room specified to be usable in January is a different product from one specified to look good in June, and the difference is mostly buried in the walls.

Insurance and paperwork

Common questions

Does a garden room need planning permission?

Often not, because outbuildings can fall under permitted development, but the rules have real conditions about height, position relative to boundaries, how much of the garden is covered and what the building is used for. A room intended to be slept in or run as a business is a different question from a home office.

Does it need building regulations approval?

A small detached outbuilding with no sleeping accommodation is frequently exempt, and the exemption has floor area and distance to boundary conditions attached. The electrical installation is notifiable whatever the building's status.

Is a garden room cheaper than an extension?

Per square metre it usually is, because it does not touch the house, needs no structural opening and often avoids a building control application. It also does not add to the internal floor area of the house, which is the trade off.

Registered contractors by region

• Registered roofers in the East Midlands postcode area
• Registered roofers in the East of England postcode area
• Registered roofers in the London postcode area
• Registered roofers in the North East postcode area
• Registered roofers in the North West postcode area
• Registered roofers in the Scotland postcode area
• Registered roofers in the South East postcode area
• Registered roofers in the South West postcode area
• Registered roofers in the Wales postcode area
• Registered roofers in the West Midlands postcode area
• Registered roofers in the Yorkshire and The Humber postcode area