Balconies and roof terraces across Kent

Guide price

£2,100–£3,600

Survey

Free for new and replacement roofs

Quote

Fixed, in writing

Coverage

England, Wales, Scotland, NI

How much does balcony or terrace waterproofing cost in Kent?

Guide prices including VAT at South East rates. The fixed price comes after a free survey for new and replacement roofs.

Which flat roofs are common in Kent?

Flat roofs in Kent sit on terraced streets with flat-roofed rear kitchens and bathrooms, low-rise post-war blocks of flats and 1960s and 1970s link-detached houses with flat-roofed garages and porches. Much of the South East sits in the drier Thames catchment at roughly 730 mm of rain a year, so the usual failures are at joints, upstands and outlets rather than from sheer volume of rain. Approximate 1991–2020 regional averages based on Met Office data.

Building regulations in England

Replacing more than half of a roof over a heated room usually counts as renovating a thermal element, so it is insulated to current standards and notified to building control. Renovated roofs over heated rooms are insulated to around 0.16 W/m²K where that's feasible, and new extension roofs are built to 0.15 W/m²K. In Kent the application goes to Maidstone Borough Council, Medway Council, Tunbridge Wells Borough Council and 10 other councils. More on the rules.

Which waterproofing system is best for a balcony?

For most small balconies, a liquid-applied membrane is the practical choice, because it is brushed or rolled on and forms one continuous layer around posts, door frames and outlets with no seams to fail. Many systems include a hard-wearing, anti-slip topcoat.

GRP fibreglass gives a rigid, walkable surface and suits balconies left exposed rather than paved. On larger roof terraces under paving or decking, single-ply membranes are common, and mastic asphalt has a long record on concrete terraces and blocks of flats.

The choice also depends on what goes on top. Paving on pedestals protects the membrane, while an exposed balcony needs a system rated for foot traffic in its own right. We specify the build-up at survey.

Do I need planning permission for a balcony or roof terrace?

For a new balcony or roof terrace, generally yes. In England, balconies and raised platforms are not permitted development for houses, so a planning application is normally needed, and the other nations have their own rules.

Re-waterproofing an existing, approved balcony that looks the same afterwards does not normally need planning. Building regulations are a separate question. A terrace over a heated room is a thermal element, so replacing most of it can bring insulation requirements and approval. Turning a flat roof into a terrace also raises structural questions, because people, furniture and paving add load, and it needs guarding, such as a balustrade, that meets the regulations. A structural engineer should confirm that the roof can carry the new use.

Listed buildings and conservation areas add another layer of control. Our building regulations page covers approvals, and our planning permission guide covers the planning side.

Which towns in Kent do we cover?

• Maidstone
• Gillingham
• Royal Tunbridge Wells
• Folkestone
• Margate
• Ashford
• Canterbury
• Sittingbourne
• Gravesend
• Dartford
• Ramsgate
• Dover
• Tonbridge
• Strood
• Whitstable
• Deal
• Sevenoaks
• Herne Bay
• Broadstairs
• Faversham
• Swanley
• Longfield
• Swanscombe

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