Before the footings: what lies under the east of the city
Dig a trench for a back kitchen in Bilston, or almost anywhere on the east side, and you are digging into coalfield country. The British Geological Survey's memoir for the Wolverhampton sheet places the exposed coalfield under the eastern side of the city, bounded by the Western Boundary Fault, and notes the seams there were worked extensively. It also says the old industries left a legacy of difficult ground.
That matters more for an extension than a loft, because you are putting new foundations into the ground. GOV.UK guidance for homeowners in former mining areas says you must check for mining risk if your house falls in a development high risk area, and there is a free online map to tell you. If the footings or new drains could disturb a seam, old workings or a mine entry, you need a permit from the Mining Remediation Authority before work starts. Householder planning applications are exempt from a coal mining risk assessment, so this is easy to miss.
West of the fault it changes. Tettenhall, Compton and Wightwick stand on Triassic sandstone, and there the usual worries are trees, slopes and the neighbours rather than what is underneath.
How the council judges a householder application
Wolverhampton's own guidance is Supplementary Planning Guidance No. 4, Extension to Houses, read alongside the design policies saved from the old Unitary Development Plan and the Black Country Core Strategy. SPG4 sets minimum distances between the back of one house and the walls of the next, and officers measure drawings against them. Ask your designer to check those figures on the plan before it goes in.
Don't treat the 45-degree line as a pass mark. Committee reports have described it as a guideline about light to habitable room windows rather than a formal test, so a scheme that clips it isn't automatically refused.
Tettenhall has an extra layer. Its neighbourhood plan, made by the council in September 2014, asks that extensions respect the area's character and take account of the spacing between buildings and the gardens around them. In Tettenhall Wood or Tettenhall Greens, filling a side gap right up to the boundary is the sort of proposal those policies were written for.
Choosing the right extension for your house
Single-storey rear. Most of the city's semis can go back 3 metres from the original rear wall without an application, or 4 metres on a detached house, up to 4 metres high. The prior approval route allows 6 or 8 metres, after the council writes to the neighbours and either decides or lets 42 days pass. Neither applies in a conservation area.
Side return. Built for the brick terraces around All Saints and Blakenhall, where a back addition leaves a narrow yard alongside. You'll be building on or near the party wall, so serve notice on next door early.
Kitchen. The three-bedroom parlour houses of Low Hill and Bushbury have kitchens sized for the 1920s. A new room across the back, opened into the old kitchen, is the job we're asked to price more than any other.
Open plan. Removing the old rear wall needs a steel and a structural engineer's calculations for the council's building control team. On the coalfield side, have the engineer look at the ground as well as the beam.
Two-storey. Over the side drive of a 1930s semi it can add a bedroom and a bigger kitchen in one go. It nearly always needs planning here, and SPG4's spacing rules will decide how close to the boundary it can come.
Wrap-around. The side leg takes it outside permitted development, so plan on an application. A semi with a side drive and a decent garden is the usual candidate.
Downstairs bedroom. A bedroom and level-access shower room on the ground floor keeps an older parent in a house with steep stairs. Leave enough garden afterwards, as officers look at what's lost.
Home office. An attached room off the back shares the house's heating and broadband. Inside a conservation area, check any tree near the footprint first.
Planning. In all 31 conservation areas a side extension, a rear one over one storey and any cladding need permission. Use the council's online register to see what was approved on your road.
Cost and value. We don't publish prices. Deeper foundations over old workings, a steel, or bricks and clay tiles matched to a Park villa can each move a quote a long way, so get three builders round.
Brooks, protected trees and frontages
Wolverhampton's 2024 Strategic Flood Risk Assessment calls surface water flood risk across the city extensive, and many of its brooks run in culverts. River flooding is worst along the Smestow Brook at Pendeford, Claregate, Wightwick and Castlecroft, the Waterhead Brook at Bushbury, the Tame and Waddens Brook at Stow Lawn, and around Bilston and Loxdale. If the Environment Agency map puts your house in Flood Zone 2 or 3, the application needs a flood risk assessment, and the agency's standing advice covers what goes in it.
Trees catch people out. In a conservation area any tree 75mm or more across, measured 1.5 metres above the ground, is protected automatically, and work to a tree with a preservation order needs the council's consent. Find out before the digger arrives.
In Park and Castlecroft Gardens, Article 4 directions mean an extension or porch on a side facing a road or open space needs permission. At The Oaks off Merridale Road the 2010 direction covers enlargement of any kind. All three apply only to houses the appraisals name as buildings of townscape merit, so check yours.
Where these facts come from
- City of Wolverhampton Council: supplementary planning documents (SPG4 Extension to Houses)
- City of Wolverhampton Council: neighbourhood planning (Tettenhall)
- City of Wolverhampton Council: conservation areas and Article 4 directions
- The Oaks (Merridale Road) Conservation Area appraisal
- Park Conservation Area appraisal
- City of Wolverhampton Council: tree preservation orders
- Wolverhampton Strategic Flood Risk Assessment Level 1 (2024), Appendix E
- British Geological Survey: Wolverhampton and Telford sheet description
- GOV.UK: home extensions and improvements in former coal mining areas
- GOV.UK: householder permitted development technical guidance
- Environment Agency: flood risk standing advice
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Questions people in Wolverhampton ask
We're in Bilston. Do we need a mining survey before building a rear extension?
Check the free development high risk area map first. If you're inside one, or the footings could reach old workings or a shaft, government guidance says you need a permit from the Mining Remediation Authority before digging.
Our house in Tettenhall Wood has a wide side garden. Will the neighbourhood plan stop a side extension?
Not on its own. The plan asks that extensions respect local character and the spacing between houses, so a modest, set-back addition stands a better chance than one built tight to the boundary.
The Smestow Brook runs behind our garden in Castlecroft. What does the council need?
Where the Environment Agency map shows the house in Flood Zone 2 or 3, include a flood risk assessment with the application. For a householder extension it follows the agency's standing advice, covering floor levels and flood resistance.
There's an old oak near where we want to build in Penn. Can we take it down?
Probably not without asking. In a conservation area a tree of 75mm diameter or more is protected, and a preserved tree needs consent. If planning permission is granted for the extension, that covers works the permission needs. Speak to the council before any cutting.