Westminster at a glance
- Postcode districts
- W1K, W1C, W1H, W1U, W1M, W1G, W1, W1J and 20 more
- Council area
- City of Westminster
- Building approval
- City of Westminster building control, or a registered building control approver
- Guide price region
- London (+20% on West Midlands rates)
What does a balcony or terrace in Westminster need?
Balcony membranes in Westminster wear out like any roof, but faster where they are exposed to foot traffic, furniture and planters. Once the topcoat has worn through or cracked around posts and edges, a full re-waterproofing usually lasts longer than repeated patching.
In a town like Westminster, flat roofs are commonly found on mansion blocks and purpose-built flats with large flat roofs or Victorian and Edwardian terraces with flat-roofed back additions. The Thames basin is one of the drier parts of Britain at roughly 730 mm of rain a year, but summer heat is the bigger test here: dark membranes on south-facing roofs swing a long way in temperature.
How much does balcony or terrace waterproofing cost in Westminster?
For Westminster we use London rates: £2,300–£3,900 is the guide for a 12 m² balcony in a liquid-applied system including scaffold, VAT included. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Balcony (12 m²), liquid-applied, scaffold | £2,300–£3,900 |
| Single garage (18 m²), EPDM rubber | £1,900–£3,350 |
| Extension (20 m²), GRP, new deck + insulation | £3,600–£6,450 |
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.
What's included?
- Strip-out of the failed membrane and deck repairs
- Lifting and setting aside of existing paving or decking
- Free survey of the deck, falls, outlets and door thresholds
- New liquid, GRP, single-ply or asphalt waterproofing
Building regulations in England
Replacing more than half of a flat roof over a heated room usually counts as renovating a thermal element, so the roof is insulated to around 0.16 W/m²K where that's technically and economically feasible, and the work is notified to building control: the council or a registered building control approver, unless a registered competent person self-certifies it. A roof on a new extension is built to 0.15 W/m²K. Patch repairs, and most unheated detached garages, don't trigger the upgrade. Structural changes, or a new covering that adds 15% or more to the roof's weight, also need approval. More on the rules.
Which nearby areas do we also cover?
- Camden · 1 mi
- Kensington and Chelsea · 2 mi
- Islington · 3 mi
- Hammersmith and Fulham · 3 mi
- Lambeth · 4 mi
- Southwark · 4 mi
Balconies and roof terraces in Westminster: questions
Do you cover Westminster?
Yes. Westminster is part of our London coverage, including postcode districts W1K, W1C, W1H, W1U, W1M, W1G and 22 more. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in Westminster?
Where the work needs approval it goes to City of Westminster building control, or a registered building control approver. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does balcony or terrace waterproofing cost in Westminster?
£2,300–£3,900 for a 12 m² balcony in a liquid-applied system including scaffold, at London guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Do you install balustrades?
Our work is the waterproofing and drainage. We detail the membrane around balustrade fixings so they stay watertight, and we can advise on where posts should be fixed.
Can you waterproof a balcony without lifting the tiles?
Sometimes a liquid system can go over a sound, well-bonded surface, but if water is already getting under the tiles they usually have to come up.