Flat or house checker

What each question decides

Kind of home

Class G sets different limits for a house and for a block of flats. A semi-detached or terraced house can have one outdoor unit, a detached house two, and each can be up to 1.5 cubic metres. A block of flats can have one unit in total, no larger than 0.6 cubic metres, which is why the checker asks whether you live in a flat. A converted house or mill made up entirely of flats is treated as a block of flats. A flat above a shop or office is the awkward case: a building with other uses may not count as a block of flats, so the checker sends you to the council.

Number of units

Two units are only allowed on a detached house. A second unit on a semi, a terrace or a block of flats needs a planning application. Most homes in Greater Manchester need only one.

Position

The unit may not go on a pitched roof, or on a flat roof within a metre of its edge. It may not go on a wall that faces a road above the ground floor, which rules out the upper front wall of a terrace and road-facing balconies above the ground floor. Ground level at the side or rear, or a flat roof set back from the edge, are the usual positions.

Listed building

Class G does not apply to a listed building or anything within its curtilage. If the building is listed, planning permission is needed, and listed building consent where the work affects its special interest. If you are not sure, check the National Heritage List or ask the council.

Conservation area

Inside a conservation area Class G still applies, but nothing may sit on a wall or roof that fronts a road, or closer to the road than the building. Councils publish maps of their conservation areas.

The conditions every unit must meet

• Pass the MCS 020 a) sound calculation at the nearest habitable-room window of a neighbouring home.
• Be placed, as far as practicable, to limit its effect on how the building looks and on the neighbours' amenity.
• Be removed as soon as reasonably practicable when it is no longer needed.
• Not be used solely for cooling.

These limits came into force on 29 May 2025, when SI 2025/560 raised the size limit on a house to 1.5 cubic metres, allowed a second unit on a detached house and removed the old rule about distance from the boundary.

Warm Homes: Local Grant routes

The result also names who delivers Greater Manchester's Warm Homes: Local Grant in the borough you choose. The scheme is area-based, so residents in selected areas are contacted by officers rather than applying.

• Manchester: For Manchester, the combined authority's page lists the delivery partner as "to be appointed".
• Salford: The Greater Manchester Combined Authority delivers the scheme in Salford.
• Stockport: The Greater Manchester Combined Authority delivers the scheme in Stockport.
• Trafford: The Greater Manchester Combined Authority delivers the scheme in Trafford.
• Wigan: The Greater Manchester Combined Authority delivers the scheme in Wigan.
• Bolton: The Greater Manchester Combined Authority delivers the scheme in Bolton.
• Bury: Bury Council runs its own delivery of the scheme.
• Rochdale: Rochdale Council runs its own delivery of the scheme.
• Oldham: The Greater Manchester Combined Authority delivers the scheme in Oldham.
• Tameside: Tameside Council runs its own delivery of the scheme.

After the checker

A result that looks like permitted development is a good sign, not a guarantee. The installer still has to show the sound calculation passes at the real position. If you want certainty, the council can issue a lawful development certificate. For a flat, get the building owner's agreement in writing before paying a deposit. The flats page and the planning rules page go further.

Behind each answer is a fuller page: heat pumps for flats for blocks and freeholders, Warm Homes in Greater Manchester for the area scheme and who delivers it, and all ten boroughs for your borough's figures.