How many households live in conversions
| Borough | Other converted building | Share | Converted or shared house | Commercial building |
|---|---|---|---|---|
| Manchester | 3,837 | 1.79% | 8,370 | 1,771 |
| Stockport | 1,004 | 0.79% | 1,730 | 1,075 |
| Bolton | 829 | 0.70% | 1,046 | 714 |
| Tameside | 680 | 0.68% | 915 | 720 |
| Salford | 702 | 0.61% | 1,606 | 690 |
| Trafford | 547 | 0.57% | 1,839 | 846 |
| Oldham | 470 | 0.50% | 556 | 549 |
| Bury | 365 | 0.45% | 888 | 541 |
| Rochdale | 356 | 0.39% | 771 | 547 |
| Wigan | 529 | 0.37% | 1,066 | 771 |
The census does not name mills specifically. Its category covers flats in any converted building other than a house, with former schools, churches and warehouses as examples. In Greater Manchester that category is largest in Manchester, where 3,837 households lived in such buildings in 2021. Across the ten boroughs, 9,319 households did, alongside 18,787 in flats carved out of houses and 8,224 in flats within commercial buildings.
A building of flats under Class G
Class G treats a building made up entirely of flats as a block of flats. That allows one air source unit for the whole building, no larger than 0.6 cubic metres, subject to the usual conditions: not on a pitched roof, at least a metre from a flat roof's edge, not on a road-facing wall above the ground floor, and passing the MCS 020 a) sound calculation. Many conversions have ground floors with shops, bars or offices. A mixed-use building may not count as a block of flats for Class G, so ask the council before relying on permitted development.
Listed buildings and conservation areas
Some converted mills and warehouses are listed, and others sit in conservation areas. Class G does not apply to a listed building or its curtilage, so a heat pump on one always needs planning permission and usually listed building consent. In a conservation area Class G still applies, but nothing may sit on a wall or roof that fronts a road. Manchester has 863 listed-building records and Oldham 554, the most of the ten. The listed buildings page sets out the order of work.
What the building itself brings
- Thick masonry walls and large window openings change how much heat each flat loses; the heat-loss survey has to measure them, not assume.
- Large windows and high ceilings raise the heat demand of each flat, and replacement windows in a listed building need consent.
- Flat roofs are common on warehouses and offer the most likely place for plant, set back from the edge.
- Shared risers and plant rooms make a communal system easier to route than one unit per flat.
Shared systems
Because Class G allows one unit per building, conversions lend themselves to shared solutions: a communal air source system feeding each flat through heat interface units, or a ground source system with a shared loop if there is land, which Class C covers within the grounds of a block of flats. Both are decisions for the freeholder and usually the residents together. A single leaseholder acting alone is limited to one small unit, with consent, or an air-to-air system inside the flat, which the Boiler Upgrade Scheme does not cover.
Who has to agree
The freeholder or management company controls the structure and the roof. Leases usually require written consent for anything fixed outside a flat or passing through its walls. In a listed building the council's consent comes on top. Start with the managing agent, find out whether the building has a plan for its heating, and ask whether other residents are interested.
Grants
The Boiler Upgrade Scheme pays £7,500 towards an air or ground source heat pump for an owner, including a landlord, through an MCS certified installer. Greater Manchester's Warm Homes: Local Grant covers owner-occupied and privately rented homes in selected areas; residents there are contacted by officers. Neither pays for a project the freeholder has not agreed to.