Edge trims, outlets and drainage across Kent

Guide price

£130–£390

Repair price

Confirmed once the leak or damage is found

Condition survey report

£170–£330

Coverage

England, Wales, Scotland, NI

How much does a new roof edge or outlet cost in Kent?

Guide prices including VAT at South East rates. We confirm the price once we've traced the leak or seen the damage.

Which flat roofs are common in Kent?

Flat roofs in Kent sit on shops with flat-roofed rear stores below flats, bungalows with flat-roofed side extensions and dormers and lock-up garage blocks on estates. 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.

Why does water sit on my flat roof?

Water sits on a flat roof because it can't drain off fast enough: the falls are too shallow, part of the roof slopes the wrong way, the deck has sagged between joists, or an outlet is blocked or set too high.

Current guidance on flat roof design (BS 6229) means most roofs need to achieve a finished fall of at least 1:80, and roofs are commonly designed with a steeper fall, such as 1:60, so that building tolerances and deck deflection still leave enough slope. Many older roofs were built with less, or have settled over time.

A small amount of water that clears within a day or two of rain is often tolerable. Deeper ponding that lingers adds weight, holds dirt and debris, can shorten the life of some coverings and turns any small defect into a leak. A patch won't fix it, because the problem is the shape of the roof. The fix is to correct the falls, either with firring pieces under a new deck or with tapered insulation in a warm roof, or to add or lower outlets so water has somewhere to go. Our ponding water guide explains this in more detail.

Should I fix the edges and drainage or replace the whole roof?

Fix the edges and drainage on their own if the covering is in good condition and the deck is sound. If the covering is near the end of its life or the falls need correcting across the whole roof, it is usually better value to do everything together as part of a replacement.

Trims and outlets are bonded into the waterproofing, so replacing them means cutting into the covering around the edge. On a roof with plenty of life left, that is a worthwhile repair. On an old, brittle covering, the new detail can end up stronger than the roof around it, and correcting falls means taking the covering off anyway. Our repair or replace guide sets out how to decide.

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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