Roof Terraces & Balconies in Poole: Costs & What to Expect

Stand on the right rooftop in Poole and you're looking at the harbour, Brownsea Island and, on a clear day, the Purbeck hills. Plenty of homes around Lower Parkstone, Lilliput and Whitecliff sit under flat roofs that do nothing except keep the rain out. Turning one into a proper walk-on terrace, or hanging a balcony off a bedroom, is some of the most rewarding work we do, and around here the view usually earns its keep.

This guide covers what the job actually involves, what it costs in 2026, and the planning quirks that catch people out. Every figure below reflects what we'd charge at current south-coast rates, checked this month, not a hopeful national average.

Why flat roofs in Poole are wasted space

Poole has an unusual amount of flat-roofed building stock. The sixties and seventies left Parkstone and Canford Cliffs full of split-level houses with flat-roofed garages and single-storey wings, and nearly every rear extension built since has a flat roof over the kitchen. Most were designed to be looked at, not stood on. That's the opportunity: the structure is often most of the way to being a terrace already, and it's usually sitting right outside a first-floor bedroom or landing.

A word of caution before you get the deckchairs out. A standard flat roof is built to carry snow and the odd window cleaner, not a dinner party. We always have the joist sizes and spans checked before quoting, because the difference between 'add a deck' and 'strengthen the structure first' changes the budget properly.

What a walk-on conversion involves

Done right, the conversion is a sequence. Skipping a step is how leaks happen.

1. Structural check. An engineer confirms the roof can take live loading: people, planters, furniture, the lot.

2. Waterproofing. GRP fibreglass laid to proper falls, specified for foot traffic. Expect £95 to £160 per square metre fitted.

3. Deck surface. Composite boards or porcelain paving on pedestals, so water drains away underneath rather than pooling.

4. Balustrade. Building Regs require guarding of at least 1.1 metres. Frameless glass is the favourite on harbour-view plots for obvious reasons.

5. Access. Usually converting a window into French or sliding doors, with a new lintel and making good inside and out.

For a typical terrace over a single-storey extension, allow two to four weeks on site. Strengthening work or awkward scaffold access adds time, which we'll flag at survey rather than spring on you mid-job.

What it costs in 2026

Terraces are priced on size, structure and spec, but these are the working numbers we quote against right now:

• GRP walk-on waterproofing: £95 to £160 per square metre fitted

• Glass balustrade with a steel handrail: £300 to £420 per linear metre; frameless systems run from around £950 per metre

• Converting a window to French doors for access: £1,800 to £4,800 depending on the lintel and structural work

• Most full conversions over a single-storey extension land between £15,000 and £30,000 all in

If the joists need beefing up first, the number moves, and we'd rather tell you that at survey than discover it on day two. A Juliet balcony is the budget-friendly cousin: no walk-out space, but you get the doors, the glass and the light for a fitted cost of roughly £600 to £1,300, plus the door conversion if you're starting from a window. Both jobs sit with our exterior works and landscaping team, who handle the structural and waterproofing side under one roof, so to speak.

Planning permission, privacy and the rules

Here's the one that surprises people: roof terraces almost always need planning permission. Permitted development doesn't cover raised platforms, so the moment you create a place to stand above 300mm, you're making an application. Overlooking is the big theme on tight Poole plots. Planners regularly ask for an obscure-glazed privacy screen along one side, and in conservation areas like Poole Old Town the bar sits higher again.

Juliet balconies usually avoid a full application because there's no platform, though flats and listed buildings are their own conversation. Either way, we sort the drawings and the application as part of the job. It's not a reason to put the idea off.

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Fancy a harbour view from your own roof?

We survey first and quote after, whether that's a full terrace or a single Juliet balcony. If you've got a flat roof in Poole, Sandbanks or anywhere along the coast doing nothing, book a survey through completebuilds.com and we'll tell you straight whether it can carry a terrace and exactly what it'll cost.

More on what we do as builders in Poole.