Ely Roofers installs and repairs flat roofs for homeowners in Newmarket, helping you catch the early signs of trouble before a small leak becomes a serious problem.
A flat roof is not truly flat. It carries a slight fall - usually around 1:80 - to push rainwater towards a drain or outlet. When that fall is lost, when the surface cracks, or when the upstands around the edges lift away, water finds somewhere it should not be. On extensions, garages and outbuildings, flat roofs are common, and most of the problems they develop follow a familiar pattern.
Understanding what to look for, and what is causing it, means you can make a sound decision rather than waiting until a damp ceiling forces your hand.
You do not need to climb onto the roof to spot many of the early signs. From ground level or an upstairs window, look for these:
Any one of these is worth acting on. Two or more together usually means the roof needs more than a patch repair.
Inside the property, flat roof problems show up as damp patches on ceilings directly below the roof, often with a tide mark as the stain dries and rewets through the seasons. Peeling paint or wallpaper near the junction between an extension ceiling and an external wall is another signal. In a garage, look for rust staining on metal items stored below - it often pre-dates a visible ceiling stain.
A key point: the place where water appears inside is rarely the same as where it is entering the roof. Water travels along joists and rafters before it drips, so a ceiling stain over one corner of a room can mean the entry point is several feet away.
Age is the obvious factor, but it rarely acts alone. The main causes of flat roof failure are:
A flat roof with a blocked outlet holds water. Even a thin layer of standing water adds significant weight and accelerates the breakdown of felt or membrane. Outlets block with leaves, moss, and debris, particularly on roofs shaded by trees. Outlets positioned at a high point of the roof - which happens when decks settle unevenly over time - simply cannot drain at all.
Where the flat roof surface meets a wall, it must turn up at least 150mm to form an upstand, then be dressed into the wall with lead or a proprietary flashing. This joint is where a large proportion of flat roof leaks begin. The upstand can lift, crack, or pull away from the wall as the membrane shrinks and expands with temperature changes. On older felt roofs, this happens gradually and is often missed until water is already inside.
The membrane or felt sits on a timber deck - typically plywood or OSB. When water gets beneath the covering, this deck absorbs moisture, swells, and eventually rots. A soft or springy feel underfoot when walking on the roof is a direct sign of deck damage. Replacing deck sections adds to the cost of a re-cover job, but skipping it and laying new felt over a compromised deck is a false economy - the new covering will fail prematurely because it has no solid base.
Flat roof membranes expand in summer heat and contract in cold winters. Over years, this movement works at joints, laps and upstands, gradually opening gaps that water can enter. Single-ply membranes such as EPDM rubber handle this movement better than traditional built-up felt because they are more elastic. Older felt systems, especially those laid in a single layer, are most vulnerable to this kind of splitting along seams.
Many flat roof problems on extensions and garages trace back to shortcuts taken when the roof was first built. Common installation errors include insufficient falls, upstands that are too short, inadequate bonding of the felt to the deck, and flashings dressed into mortar joints rather than into purpose-cut chases. A roof installed correctly from the start will outlast one that was done cheaply by a decade or more.
A repair is appropriate when the roof deck is sound, the failure is localised - a split at one upstand, a blister in one section - and the rest of the covering is still adhered and intact. A re-cover is the better answer when the deck is soft in more than one area, when the felt has multiple splits or is losing its surface, or when the roof is more than 15-20 years old and has already been patched more than once.
Patching over a widespread problem buys time but rarely solves it. Water finds the next weak point, and you end up spending the repair cost twice within a few years. Ask any roofer you speak to to be clear about which of the two categories your roof falls into, and why.
A straightforward repair - sealing a split upstand or re-dressing a small area of failed flashing - typically runs from £150 to £400 depending on access and materials. A full re-cover of an average garage or single-storey extension roof (say 20-30 square metres) in EPDM rubber generally costs £1,500 to £3,000 installed, with felt re-covers sitting at the lower end of that range and more involved decking repairs pushing the total higher. The exact price depends on what the deck reveals once the old covering comes off.
If you can see any of the warning signs described above on a flat roof in Newmarket, call us for a roof survey so we can give you a straight assessment of what needs doing and what it will cost.
If you are unsure whether we cover your area, give us a call and we will confirm.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
