Monmouth at a glance
- Postcode districts
- NP25
- Population
- about 10,110 (GeoNames)
- Council area
- Monmouthshire County Council
- Building approval
- Monmouthshire County Council building control, or a registered building control approver
- Nearest main town
- Abergavenny, about 13 miles
- Guide price region
- Wales (−8% on West Midlands rates)
What does a balcony or terrace in Monmouth need?
A roof terrace in Monmouth may be re-waterproofed when the owners want to change the finish, swapping old tiles for decking or porcelain on pedestals. Lifting the surface exposes the membrane, and replacing it then avoids having to lift the new finish again later.
In and around Monmouth, flat roofs are typically found on 1960s and 1970s link-detached houses with flat-roofed garages and porches, and on shops with flat-roofed rear stores below flats. Wales averages roughly 1,460 mm of rain a year, among the wettest in Britain, so we design for steady run-off: proper falls, clear outlets and upstands well above the finished roof.
How much does balcony or terrace waterproofing cost in Monmouth?
For Monmouth we use Wales rates: £1,750–£3,000 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 | £1,750–£3,000 |
| Single garage (18 m²), EPDM rubber | £1,450–£2,600 |
| Extension (20 m²), GRP, new deck + insulation | £2,750–£4,950 |
How are thresholds, drainage and paving handled on a terrace?
They are designed together, because most balcony leaks start at the door threshold, a blocked outlet or a fixing driven through the membrane. Getting those three right matters more than the brand of membrane.
Thresholds: upstands are usually 150 mm above the finished surface, but a level or low step-out door cannot always achieve that. Where the upstand has to be reduced, extra protection is needed, such as a drainage channel at the door and a fall away from it, and the membrane must still run up and under the door sill.
Drainage: every terrace needs a reliable way off for water, with outlets sized for the area and an overflow if one outlet could block. Outlets under paving need access for cleaning.
Inverted roofs and pedestals: on an inverted roof the insulation sits above the waterproofing and is held down by paving or ballast, protecting the membrane from sun and foot traffic. Adjustable pedestals lift paving slabs level above the falls, so water drains underneath and the surface stays flat. Balustrade posts are fixed through upstands or side-fixed where possible, with every penetration sealed into the membrane.
What's included?
- Sealed details at doors, outlets, walls and balustrade posts
- Strip-out of the failed membrane and deck repairs
- Lifting and setting aside of existing paving or decking
- New liquid, GRP, single-ply or asphalt waterproofing
Building regulations in Wales
The Welsh Approved Document L applies. Renovating more than half of a roof over a heated room means upgrading it to around 0.16 W/m²K where feasible, and new extension roofs are built to 0.13 W/m²K. Welsh Government guidance is that most re-roofing needs building control approval, so check whenever more than a quarter of a roof is replaced or repaired. We deal with the application as part of the job. More on the rules.
Which nearby areas do we also cover?
Balconies and roof terraces in Monmouth: questions
Do you cover Monmouth?
Yes. Monmouth is part of our Monmouthshire coverage, including postcode districts NP25. 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 Monmouth?
Where the work needs approval it goes to Monmouthshire County Council 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 Monmouth?
£1,750–£3,000 for a 12 m² balcony in a liquid-applied system including scaffold, at Wales guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
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.
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.