Annexe extensions across Plumstead
Planning an annexe extension in Plumstead? We survey the house, work out the planning route, draw the design and build it, so you deal with one team from the first visit to the completion certificate.
- Guide price in PlumsteadFrom £71,500 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsDA16, SE2, SE18, SE28
Will the council need to approve it?
In England an annexe that stays part of the household and connects to the house is assessed as an extension, but its size usually takes it beyond permitted development, so a householder application describing the ancillary use is the normal route.
The planning position for a specific Plumstead address depends on its history and any designations, which is why we check it at the first visit.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
Guide prices for Plumstead
Prices below are for Plumstead, using the London factor of ×1.3. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Plumstead: £2,600 to £4,940 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £71,500 – £89,500 | £78,000 – £97,500 | £97,500 – £123,500 |
| One-bedroom annexe 35 m² | £91,000 – £114,000 | £109,000 – £136,500 | £136,500 – £173,000 |
| Larger annexe 45 m² | £117,000 – £146,500 | £140,000 – £175,500 | £175,500 – £222,500 |
Try the guide-price tool to see a range for your own size and finish.
Local to Plumstead
Postcode districts we cover around Plumstead include DA16, SE2, SE18, SE28. The same team covers Abbey Wood (1 mile), Welling (2 miles), Thamesmead (2 miles), Eltham (3 miles), all within easy reach.
Dartford, in Kent, is roughly 6 miles from Plumstead and also on our list. In London, space is at a premium and gardens are often short, so side returns, wraparounds and carefully planned rear extensions tend to make the most of every metre.
When an annexe extension makes sense
- Multi-generational families
- Relatives who need support close by
- Homes with a large side or rear garden
Accessibility is cheaper to design in than to retrofit. Level access, a 900 mm door width, a level-access shower and space to turn a wheelchair can all be planned into the footprint for little extra cost.
What happens next
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Common questions in Plumstead
How long does an annexe extension take to build in Plumstead?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 10–16 weeks design and approvals.
Do you cover all of Plumstead?
Yes. We cover Plumstead and the surrounding parts of Greater London. Site visits are free and there is no obligation.
Do I need building regulations approval in Plumstead?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Does an annexe extension need planning permission?
Usually yes, because of its size and the way it will be used. Councils check that it stays ancillary to the main house, so the application must describe the use clearly.
How much does an annexe extension cost?
Our guide range is about £2,600 to £4,940 per m² including VAT. A one-bedroom annexe of about 35 m² is typically £109,000 to £136,500 at standard spec in Plumstead.
Book a free site visit in Plumstead
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.