Edge trims, outlets and drainage across Belfast

Guide price

£110–£310

Repair price

Confirmed once the leak or damage is found

Condition survey report

£130–£260

Coverage

England, Wales, Scotland, NI

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

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

Which flat roofs are common in Belfast?

Flat roofs in Belfast sit on terraced streets with flat-roofed rear kitchens and bathrooms, 1930s semis with flat-roofed garages and kitchen extensions and bungalows with flat-roofed side extensions and dormers. Northern Ireland averages roughly 1,150 mm of rain a year, spread over many wet days, so a roof that sheds water quickly to clear outlets lasts far longer than one that holds puddles. Approximate 1991–2020 regional averages based on Met Office data.

Building control in Northern Ireland

In Northern Ireland, renovating or replacing a roof over a heated room usually means meeting Technical Booklet F1, and building control should be contacted before work starts. Technical Booklet F1 sets roof insulation at 0.18 W/m²K when a roof over a heated room is renovated or newly built, where feasible. In Belfast the application goes to Belfast City Council. More on the rules.

How long do flat roof trims and outlets last?

Properly fixed GRP or aluminium trims and well-installed outlets should last about as long as the waterproofing they are part of. What shortens their life is poor fixing, movement in a rotten deck edge and blockages that are never cleared.

A quick check of outlets and gutters each autumn, and again after storms, prevents most drainage problems. Look for leaves and silt in outlets, gutters pulling away from the fascia, trims that have lifted or split at joints and staining on the wall below the edge. The maintenance guide lists what to check and when. Only check what you can see safely from the ground, a window or a ladder at the edge, and never walk on a roof that isn't designed for it.

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.

Which towns in Belfast do we cover?

• Belfast

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