New Pitsligo · Aberdeenshire
Flat Roofing in North Aberdeenshire — EPDM, GRP & Felt
Flat roofs do not fail because they are flat. They fail because water sat on them, and water sat on them because the falls were wrong.
Getting the falls right first
Before we talk about coverings we look at where the water is meant to go. A flat roof needs a fall of at least 1:80 after the timbers have deflected, and plenty of the ones we replace around here were laid dead level. Ponding water finds every weakness, freezes in it over winter and opens it up. We build the fall in with firring strips over the joists, and we put the outlet at the lowest point rather than wherever the old one happened to be.
The three coverings we fit
EPDM rubber
A single sheet of rubber over the whole roof, so on most domestic roofs there is not a single seam in the field. It stays flexible in the cold, which matters more here than it does further south, and it copes well with the movement you get on a timber deck. It is what we fit most often on garages, extensions and dormers.
GRP fibreglass
Laid wet and cured in place into a single rigid skin with no joints in it. It takes foot traffic better than rubber, so it is the right choice for a balcony or a roof somebody will actually walk on. The catch is that it needs dry conditions and a workable temperature to cure properly — on the Banffshire coast that limits when we can lay it, and we would rather move a job by a week than lay it in the wrong weather and watch it fail.
Torch-on felt
Modern three-layer built-up felt, not the single-layer material that gave felt roofs their reputation. It is hard-wearing, easy to detail around awkward upstands, and straightforward to repair in years to come.
Cold deck, warm deck and condensation
If a flat roof has insulation between the joists and no ventilation above it, moisture condenses on the underside of the deck and rots it from inside. That roof will look sound from above right up until the day it sags. Where we can, we rebuild as a warm deck with the insulation above the joists, which takes the problem away entirely. Where the height will not allow it, we ventilate the void properly instead.
Edges matter too: drip trims, upstands taken high enough at abutments, and lead flashings chased into the wall rather than smeared over with mastic.
Questions about flat roofing
How long should a flat roof last?
A properly laid EPDM or GRP roof with correct falls should be good for decades rather than years. The failures we get called to are almost always down to the falls being wrong or the detailing at the edges, not the covering wearing out. All our work is guaranteed.
Can you overlay my existing flat roof?
Only if the deck underneath is dry and sound, and we will not know that without lifting a section. Overlaying a wet deck traps the moisture and you pay twice.
Is a flat roof suitable for a balcony?
Yes, but it needs a system rated for foot traffic — GRP with a non-slip finish, or EPDM under a proper walk-on deck. Standard rubber on its own will not take it.
Flat roof past its best?
Send us a photo or let us come and look. Most of the flat roofs we replace around here failed because the falls were wrong, and that is fixable.