Balconies and roof terraces across Hertfordshire

Guide price

£2,000–£3,400

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 Hertfordshire?

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

Which flat roofs are common in Hertfordshire?

Flat roofs in Hertfordshire sit on bungalows with flat-roofed side extensions and dormers, newer estates where the first extension roofs are now being replaced and low-rise post-war blocks of flats. The East of England is the driest part of Britain, with parts of the Anglian region around 630 mm a year, so summer heat and UV, not rainfall, do most of the ageing on a felt roof. 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 Hertfordshire the application goes to Watford Borough Council, Dacorum Borough Council, Stevenage Borough Council and 7 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.

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.

Which towns in Hertfordshire do we cover?

• Watford
• Hemel Hempstead
• Stevenage
• St Albans
• Welwyn Garden City
• Cheshunt
• Hatfield
• Bishop's Stortford
• Borehamwood
• Hitchin
• Hoddesdon
• Letchworth Garden City
• Harpenden
• Bushey
• Hertford
• Rickmansworth
• Potters Bar
• Berkhamsted
• Ware
• Royston

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