- Guide price
- £110–£320
- Repair price
- Confirmed once the leak or damage is found
- Condition survey report
- £140–£280
- Coverage
- England, Wales, Scotland, NI
Gwynedd at a glance
- Largest towns
- Bangor, Gwynedd, Caernarfon
- Postcode areas
- LL
- Building control
- Gwynedd Council
- Neighbouring areas
- Isle of Anglesey · Conwy · Denbighshire · Flintshire
- Guide price region
- Wales (−8% on West Midlands rates)
How much does a new roof edge or outlet cost in Gwynedd?
Guide prices including VAT at Wales rates. We confirm the price once we've traced the leak or seen the damage.
| Job | Guide price inc VAT |
|---|---|
| Outlet or drainage repair | £110–£320 |
| Localised patch repair | £140–£460 |
| Upstand or flashing repair | £230–£600 |
| Emergency temporary weatherproofing visit | £170–£410 |
| Condition survey and leak investigation | £140–£280 |
Which flat roofs are common in Gwynedd?
Flat roofs in Gwynedd sit on 1960s and 1970s link-detached houses with flat-roofed garages and porches, low-rise post-war blocks of flats and bungalows with flat-roofed side extensions and dormers. 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. Approximate 1991–2020 regional averages based on Met Office data.
Building regulations in Wales
Welsh guidance is that most re-roofing needs building control approval, so it's worth checking whenever more than a quarter of a roof is replaced or repaired. Renovated roofs are upgraded to around 0.16 W/m²K where feasible, and new extension roofs are built to 0.13 W/m²K under the Welsh Approved Document L. In Gwynedd the application goes to Gwynedd Council. 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.
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.
Which towns in Gwynedd do we cover?
Edge trims, outlets and drainage in Gwynedd: questions
Which towns in Gwynedd do you cover?
All of Gwynedd. 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 a new roof edge or outlet cost in Gwynedd?
£110–£320 for an outlet or drainage repair, at Wales guide rates including VAT. We confirm the price once we've traced the leak or seen the damage.
Which council handles building control for a flat roof in Gwynedd?
It depends on where the roof is: in Gwynedd that's Gwynedd Council. Welsh guidance is that most re-roofing needs building control approval, so it's worth checking whenever more than a quarter of a roof is replaced or repaired. We confirm which applies at the survey.
Is some standing water on a flat roof normal?
A thin film that clears within a day or two of rain is common and usually harmless. Deeper water that lingers for days points to poor falls, a sagging deck or a blocked outlet and should be looked at.
Can a flat roof be re-laid with better falls?
Yes, as part of a replacement. Falls are corrected with tapered firring pieces under a new deck or with tapered insulation in a warm roof build-up.
Why is my fascia rotting under a flat roof?
Usually because water is getting behind a loose or badly lapped trim, or running back under the edge because there is no proper drip. The fascia and deck edge are replaced and new trims are fitted to stop it happening again.
Everything about edge trims, outlets and drainage → · All flat roofing in Gwynedd →