Where the harbour reaches the back garden
Start with the tide tables, not the kitchen brochure. The council says Poole carries more tidal and river flood risk than Bournemouth. The Environment Agency runs named flood warning areas around the harbour edge. One covers Lower Hamworthy and the stretch from the Old Town and the Quay up to Hunger Hill. Another takes in Hamworthy Park, Moriconium Quay and parts of Lulworth Avenue and Branksea Avenue. A third reaches Sandbanks, naming Panorama Road and Banks Road among others.
Living in one of those areas doesn't stop you building. It changes the paperwork. If your plot sits in Flood Zone 2 or 3, a planning application for an extension has to carry a flood risk assessment. The Agency's standing advice for householders asks for the new floor to sit 600mm above the estimated flood level (300mm where that level is known with high certainty), or for the walls and services to be built to resist and recover from water up to that height.
Around Holes Bay alone the council counted 570 properties at tidal risk, rising past 2,000 within a century without a new defence. Check your postcode on the flood map before anyone draws.
Then think about what's under the lawn. Parkstone gave its name to a ball clay that was dug from pits there, and the British Geological Survey notes that most of those pits have since been filled. The same survey flags old underground clay workings and wide areas of landfill across the Poole and Bournemouth sheet. Trial holes cost little next to redesigning footings halfway through.
Ten ways to add room, ranked for Poole
Ordered for Poole's mix of estate semis, detached plots and low-lying streets. Each opens a full guide.
Single-storey rear. On a Canford Heath semi it's often the whole answer: 3 metres without an application, 4 on a detached house, and prior approval can stretch that to 6 or 8. Near the harbour, settle the floor level before the depth.
Ground-floor bedroom. Broadstone's neighbourhood plan wants its older bungalows to stay available for people downsizing, so a level bedroom and shower room at the back fits its thinking better than a new upper floor. Keep it linked to the house. A self-contained flat near protected heath is judged as a new home, not an extension.
Kitchen. If the garden looks over the harbour, the view is the brief. Spend on the glazing and its frame before you spend on extra floor area.
Two-storey. Planners will test it against Local Plan Policy PP27, which asks extensions to respect and relate to the existing building. On a detached Branksome or Lower Parkstone house, that usually means a lower ridge and the same brick.
Wrap-around. Needs a side drive or a wide plot, which many detached Poole houses have. The side leg always needs an application in a conservation area such as Ashley Cross or Branksome Park.
Open plan. Taking out the back wall of a 1970s estate house usually means a steel beam and padstones. On made ground or soft clay, the engineer should see the trial hole before sizing the footings under them.
Home office. Attach it if you can. A cabin at the end of a Branksome Park garden is likely to sit among protected pines, and the roots will decide where the base goes.
Side return. Mostly a job for the smaller Victorian houses of Upper Parkstone, though fewer than one BCP home in ten is terraced. Filling the passage counts as a side extension in planning terms.
Planning. Before drawings, check four things. Is it a conservation area, a flood warning area or a flat, and are the trees protected? In Broadstone, read the neighbourhood plan as well.
Cost. We publish no Poole figure. A raised floor and flood-resilient walls at Hamworthy, or deep footings over old clay pits, can move a price more than the size of the room. Compare three quotes line by line.
Broadstone writes its own rules on extensions
Broadstone is the one part of Poole with a neighbourhood plan policy aimed squarely at householders. The plan, made in June 2018 and running to 2033, includes Policy BP8, Well-designed Extensions. Its stated aim is to meet demand for bigger homes from the houses already there, rather than by building new ones. It also flags drainage and lost garden space.
The plan is frank about bungalows. It says raising ridge heights and adding dormers on older bungalow roads, naming Fontmell, Steepleton, Bognor and Cheam Roads, cuts the supply of smaller homes that older residents want to move into. That bans nothing, but a ground-floor extension that keeps the bungalow a bungalow is the easier case to make.
One trap. Broadstone's 2023 Residential Design Guide and Codes says in terms that it excludes extensions to existing buildings. Don't let a designer quote it as your extension rulebook. The plan also notes that many Broadstone trees carry preservation orders.
What a Poole house can do without an application
Poole has no householder extension guide and no Article 4 direction removing extension rights, so national rules do most of the work. Besides the rear depths above, you can add a single-storey side extension up to 4 metres high and half the width of the original house. A two-storey addition at the back can go 3 metres deep if it stays 7 metres clear of the rear boundary.
Those rights shrink inside any of Poole's conservation areas. There, side extensions, rear additions of more than one storey, and cladding all need permission, and the larger prior approval route is closed. Flats get no householder rights at all. In Branksome Park, a new gate or wall on the road frontage for a side access also needs consent under the 1993 Article 4 direction.
Trees catch people out more than rooflines do. In a conservation area, any tree whose stem is over 7.5cm across at 1.5 metres above ground needs six weeks' written notice before work. Felling or lopping a tree under a preservation order without consent is a criminal offence.
Where these facts come from
- GOV.UK: permitted development rights for householders, technical guidance
- GOV.UK: flood risk assessment standing advice
- Environment Agency: Poole Harbour at West Quay and Lower Hamworthy Quay
- Environment Agency: Poole Harbour at Hamworthy Park
- Environment Agency: Poole Harbour at the Town Quay (incl. Sandbanks roads)
- BCP Council: strategic flood risk assessment
- BCP Council: Poole Bridge to Hunger Hill flood defence
- BCP Council: local plan for the Poole area and Article 4 directions
- Broadstone Neighbourhood Plan (2018)
- Broadstone Residential Design Guide and Codes (2023)
- BCP Council: trees in conservation areas
- BCP Council: tree preservation orders
- BGS Lexicon: Parkstone Clay Member
- BGS: geology of the country around Bournemouth
- Dorset Heathlands Planning Framework 2020 to 2025 SPD
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Questions people in Poole ask
We live off Panorama Road on Sandbanks. Does a rear extension need a flood risk assessment?
Panorama Road is named in an Environment Agency harbour flood warning area. If the plot is in Flood Zone 2 or 3 and the extension needs planning permission, send a flood risk assessment with it.
Can we extend our Broadstone bungalow outwards instead of up?
The neighbourhood plan leans that way. It worries about older bungalows losing their single-storey form, and supports extensions that meet a family's needs within the existing stock. Drainage and garden space are what Policy BP8 flags.
Our Parkstone garden may be on an old clay pit. Does that change the footings?
It can. The British Geological Survey records that most Parkstone clay pits were filled. Fill and soft clay may need deeper or engineered foundations, so dig trial holes and let building control see them early.
We're in Branksome Park and need a wider gate for builders' access. Is that allowed?
Ask first. An Article 4 direction there means new or altered gates, walls and fences on the road frontage need planning permission. Check the pines too.