Garden Room Building Regulations Explained

Planning permission and building regulations are two separate things — and it catches a lot of people out. You can be exempt from planning permission and still need to meet building regulations, depending on how you plan to use the space.

When building regs apply

Generally, a detached garden room with less than 15m² of internal floor area doesn’t need building regulations approval, as long as it has no sleeping accommodation. Between 15m² and 30m², the exemption still applies if there’s no sleeping accommodation and the room is either at least 1m from any boundary or built substantially from non-combustible materials.

Building regulations are likely to apply if:

• The room includes sleeping accommodation, such as a guest bedroom or annexe
• It’s between 15m² and 30m², within 1m of a boundary, and built mainly from combustible materials such as timber
• It’s over 30m² in internal floor area
• It includes drainage for a toilet, shower or sink — the drainage and waste connections need to comply even when the building itself is exempt

If you’re unsure, your local council’s Building Control team can confirm what applies to your plans.

What good practice looks like anyway

Even when a project is exempt, we build to a standard that would pass building regulations if it needed to — proper insulation, safe electrics installed by a qualified electrician, and structurally sound foundations. It’s the difference between a garden room that lasts one mild winter and one that lasts decades.

Electrical and fire safety

Any electrical work has to comply with Part P of the building regulations regardless of the room’s exemption status. We use certified electricians and provide the paperwork (an Electrical Installation Certificate) so you have a record for insurance and any future house sale.

Every Oaklight build meets these standards as part of our CoreBuild specification, whether or not your specific project is exempt. Have questions about your particular plot? Get in touch for a straight answer.