- Guide price
- £1,850–£3,200
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Northamptonshire at a glance
- Largest towns
- Northampton, Corby, Kettering, Wellingborough
- Postcode areas
- NN
- Building control
- West Northamptonshire Council and North Northamptonshire Council
- Neighbouring areas
- Leicestershire · Bedfordshire · Warwickshire · Cambridgeshire
- Guide price region
- East Midlands (−2% on West Midlands rates)
How much does balcony or terrace waterproofing cost in Northamptonshire?
Guide prices including VAT at East Midlands rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Balcony (12 m²), liquid-applied, scaffold | £1,850–£3,200 |
| Single garage (18 m²), EPDM rubber | £1,550–£2,750 |
| Extension (20 m²), GRP, new deck + insulation | £2,950–£5,300 |
Which flat roofs are common in Northamptonshire?
Flat roofs in Northamptonshire sit on low-rise post-war blocks of flats, lock-up garage blocks on estates and newer estates where the first extension roofs are now being replaced. The East Midlands is drier than the west of Britain, so most flat roofs here fail through age, UV and poor detailing at upstands rather than sheer rainfall. 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 Northamptonshire the application goes to West Northamptonshire Council and North Northamptonshire Council. More on the rules.
How long does it take to waterproof a balcony?
A small balcony is typically waterproofed in two to four working days, plus time for scaffold if it is above ground floor. Liquid and GRP systems need dry weather and cure time between coats, which sets the pace.
The balcony door will be out of use while the membrane is laid and curing, and the room behind may be noisy while old paving or screed is broken out. If the team needs to work through the house, we agree a route and protect floors. Larger terraces with paving or decking take longer, because the finish has to be lifted and reinstated. Resin systems smell while they cure, so nearby windows are best kept closed.
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 Northamptonshire do we cover?
Balconies and roof terraces in Northamptonshire: questions
Which towns in Northamptonshire do you cover?
All of Northamptonshire. The main towns have their own pages below, and if yours isn't listed we still cover it: send your postcode and we'll confirm.
How much does balcony or terrace waterproofing cost in Northamptonshire?
£1,850–£3,200 for a 12 m² balcony in a liquid-applied system including scaffold, at East Midlands guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Which postcode areas do you cover in Northamptonshire?
All of Northamptonshire, including the NN postcode areas. Send your full postcode and we'll confirm.
Is a roof terrace heavier than a normal flat roof?
Yes. Paving, people, planters and furniture all add load, so a structural engineer should confirm the roof can carry it before a terrace is formed.
How long does balcony waterproofing last?
It depends on the system and how well it is protected. As indicative ranges, liquid-applied systems last 10–25+ years by product and mastic asphalt 30–60, with good maintenance.
Why is water coming through the ceiling below my balcony?
The usual causes are a failed door threshold, a blocked or poorly sealed outlet, or a fixing through the membrane. A survey, sometimes lifting paving, finds the source.
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