No Oldham rulebook, so the drawings do the talking
Plenty of councils hand you a householder design guide with a 45 degree line and a maximum depth printed on it. Oldham doesn't. Its Residential Design Guide from 2007 is about new housing estates and leaves individual householder schemes out. The council's own design topic paper for the draft Local Plan (December 2023) admitted there was "a lack of specific policy responses" for extensions and outbuildings.
What planners use instead are two general policies from the 2011 Joint Development Plan Document. Policy 9 covers the effect on neighbours, so loss of light and privacy. Policy 20 covers design. Reports on Oldham householder applications weigh each scheme on its merits against those, and flat roofs get a cool reception.
I'd see that as a reason to spend a little more on drawings, not less. With no fixed test to point at, an application is won by showing the neighbour's kitchen window won't lose its light and that the roof matches the house. The council runs a paid pre-application service for householder extensions. Send photos and a 1:50 or 1:100 sketch and you get an emailed view on whether the scheme looks acceptable before you commit to full plans.
Oldham's newer Local Plan work brings in a householder policy, D4. It asks for extensions that are subordinate to the original house and in keeping with the street, with room left for parking and bins, and some garden. Rainwater should run to a permeable surface or a soakaway where possible. Its supporting text says an addition that grows the original house by more than 40% is less likely to be approved, measured as net floorspace.
Choosing the right type for an Oldham house
Terraces are the biggest share of the borough's homes and semis come next, with mill-era streets in places like Werneth and Derker. That mix decides which of these makes sense.
Single storey at the back. Outside a conservation area or the National Park, a terrace or semi can go 3 metres past the original rear wall without an application, or 4 metres on a detached house. Prior approval stretches that to 6 or 8 metres, and the neighbours are asked first.
Kitchen. Behind a stone or brick terrace the old back kitchen is often the darkest room in the house. Spend on rooflights and a wide opening before chasing extra floor area.
Open plan. Knocking through the back wall of a Victorian house means a steel beam and padstones sized by an engineer. Building control will want those calculations, so have them done before the builder prices the job.
Side return. Fits end terraces and semis with a passage down the side. In any of Oldham's conservation areas a side extension always needs planning permission, however small.
Wrap-around. Best suited to a semi or detached house with a drive down the side. Because it runs along the side, it needs an application, and planners will look hard at how much bigger it makes the house.
Two storey. Permitted development only covers one that stays within 3 metres of the rear wall and 7 metres from the back boundary. Most terraced gardens here are shorter than that, so plan on a full application and a pitched roof.
Ground floor bedroom. Good for staying put in a terrace where the stairs have become the problem. Allow room for a level threshold and a shower room off the bedroom, not just the bed.
Home office. A small attached study at the back keeps you inside the house's heating and wiring.
Planning. Start with three checks. Is the house in a conservation area, in the Peak District National Park, or in the Green Belt? A yes to any of them changes what you can build without asking.
Cost. We don't publish an Oldham figure. A block-and-render kitchen on a Chadderton semi and a stone-faced extension in Dobcross are priced very differently, so get site visits.
Coal underneath, rivers alongside
Oldham sits on the Coal Measures. Crompton, Chadderton, Hollinwood, Werneth, Glodwick and Oldham Edge were all mined, and some of the earliest workings were shallow drifts into the hillside. GOV.UK advice for homeowners in former coalfields is to check the Mining Remediation Authority's map for a development high risk area before digging footings. A coal mining risk assessment is only needed if the council asks for one. If the excavation hits an old shaft or seam, stop and ring the hazard line on 0800 288 4242.
Flooding is the other thing to look up. The council's flood risk study records the River Beal flooding about 350 properties in Shaw in 1964, and repeat floods in Uppermill and Greenfield in 1983, 2000 and 2008. Flash floods hit Grotton Hollow and Scouthead in 2009. If your plot is in Flood Zone 2 or 3, a householder extension needs a flood risk assessment with the application, and the Environment Agency's standing advice for minor extensions covers how to write it.
Saddleworth, the moors and the Green Belt
East of the town the rules tighten. Most of Oldham's conservation areas are Saddleworth villages, and in any of them a side extension, a rear extension of more than one storey and any cladding all need planning permission. The longer 6 or 8 metre prior approval route isn't available either. In the part of Saddleworth inside the Peak District National Park the same limits apply, and the application goes to the National Park Authority, not Oldham.
If your house is in the Green Belt, check the council's policies map to be sure. The council's Green Belt policy work says an extension there shouldn't be disproportionate to the original building, meaning the house as it stood in 1948 or as first built. Past 40% of that original volume, counting earlier additions, approval becomes less likely, and the council says the 40% is not a target.
Where these facts come from
- Oldham Council: building control, extensions
- Oldham Council: householder pre-application advice
- Oldham Draft Local Plan: design topic paper (December 2023)
- Oldham Local Plan: Achieving High Quality Design (January 2026)
- Oldham Local Plan: Natural Environment and Open Land (January 2026)
- Oldham Strategic Flood Risk Assessment Level 1
- GOV.UK: permitted development rights for householders, technical guidance
- GOV.UK: home extensions in former coal mining areas
- GOV.UK: flood risk assessment standing advice
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Questions people in Oldham ask
Does Oldham Council use the 45 degree rule for extensions?
Oldham has no householder design guide that sets one. Planners judge the effect on neighbours' light and outlook case by case under the general amenity policy. Showing that clearly on your drawings is the best defence.
My extension needs building regulations, but who do I contact?
Oldham Council's own building control team, on 0161 770 4122 or building.control@oldham.gov.uk, unless your builder uses a registered private approver. The council says most domestic extensions need approval, and so does building within 3 metres of the centre line of a public sewer.
Can I get a quick view from the council before paying for full plans?
Yes. Oldham runs a paid pre-application service just for householder extensions and outbuildings. Send photos, a description and scaled sketches and you get an emailed reply on the planning issues and what a valid application needs.
I live in Shaw near the River Beal. Will flooding stop me extending?
Not on its own. Check the Environment Agency flood map first. If you're in Flood Zone 2 or 3 the application needs a flood risk assessment, and the floor level and materials of the new room will need some thought.