Flat Roofing in Dereham

How we handle flat roofing

Flat Roofing in Dereham

Flat roofs are found on extensions, garages, bay windows, commercial outbuildings, and dormer structures throughout Dereham and the villages nearby. They are practical and space-efficient, but they demand more attention than a pitched roof because water sits on them rather than running straight off. A flat roof that has been poorly installed or left too long without maintenance will let water in, often without any obvious sign until the damage has already spread to the ceiling or timber below.

We install, repair, and replace flat roofs across Dereham and the surrounding Norfolk market towns. Whether you have a single-storey extension that has started to drip in the kitchen or a garage roof that is visibly cracked and pulling away at the edges, we can assess what is needed and give you a straight answer about whether a repair is realistic or a full replacement is the better option.

Flat Roof Systems We Use

Built-up felt and EPDM rubber membrane are two common systems. Each has its place depending on the size of the roof, the budget, and what is already there.

• Built-up felt: A layered system using bonded bitumen felt sheets, usually two or three layers torched or bonded together. It is a proven, cost-effective solution for smaller roofs and is straightforward to repair in sections if a problem develops later.
• EPDM rubber membrane: A single-ply synthetic rubber sheet bonded to the deck. EPDM is highly resistant to UV degradation and temperature cycling, which matters in Norfolk where roofs face open-sky exposure. A well-laid EPDM membrane can perform for several decades before needing replacement, and the manufacturer typically provides its own product warranty covering the material itself.

The choice between the two is not simply about cost. Roof size, deck condition, drainage arrangement, and how the roof connects to walls and parapets all affect which system is the right fit. We will always explain the options before any work starts.

What the Work Actually Involves

A flat roof replacement is not just peeling off the old felt and rolling something new on top. The timber deck underneath must be inspected for rot, softness, and movement. Some decks are tongue-and-groove boarding that has dried, shrunk, and left gaps. Those gaps telegraph through any membrane laid over them and cause premature failure. If the deck is compromised, it needs to be replaced with exterior-grade plywood before any membrane goes down.

Falls matter too. A flat roof should never be truly flat. Building regulations require a minimum fall of 1:80, and in practice 1:40 is better, to ensure water drains toward the outlet rather than pooling. Ponding water is one of the most common causes of early membrane failure. Where the existing structure does not have adequate fall, tapered insulation boards can be used to create the correct angle without rebuilding the whole structure.

Detailing at upstands, abutments, and around outlets is where many flat roofs fail. The join between the membrane and a wall, parapet, or soil pipe is a stress point, and it must be dressed correctly with the right flashing or upstand height. Cutting corners at these junctions is what causes leaks that are surprisingly difficult to trace.

Flat Roof Repairs

Not every flat roof problem requires a full replacement. Blistering, cracking, or a small split in the felt can sometimes be patched effectively if the rest of the membrane is in sound condition and the deck beneath is solid. A common problem is pooling water that has been sitting long enough to break down the felt at its lowest point. If the deck and falls are still good, a targeted repair and the addition of a new outlet or drainage improvement can buy several more years of performance.

We will always tell you honestly when a repair is not worth the money. If a felt roof is brittle, heavily crazed across its surface, or has had multiple patches applied over the years, another patch is unlikely to last. In those cases, a replacement is more economical in the medium term.

Flat Roofs on Extensions and Garages

Single-storey extensions are a common place for flat roofing work. Felt becomes brittle with age, especially on south-facing roofs that get prolonged sun exposure, and loses the flexibility it needs to cope with the movement that timber structures make through seasonal temperature changes.

Garages present a slightly different challenge. They are often left until water is coming through the ceiling or pooling on the floor inside. By that point there is frequently felt that has split at the drip edge, a blocked or missing outlet, and sometimes wet timber in the wall plate below. Addressing a garage roof promptly avoids that secondary structural damage.

Insulation and Warm Roof Construction

If you are replacing a flat roof on a habitable room, such as an extension used as a living area, it is worth considering a warm roof build-up. In a warm roof, the insulation sits above the deck and beneath the membrane, which keeps the structural timber above the dew point and reduces the risk of condensation damage. It also improves thermal performance significantly. Building regulations now set minimum U-value requirements for flat roofs on extensions, and a warm roof build-up is generally the most straightforward way to meet them.

What to Expect When We Carry Out the Work

Before any work starts, we will inspect the existing roof, check the deck, and look at how water is currently draining. We will give you a clear breakdown of what needs to happen and why. If the job involves stripping the old covering, we make sure the deck is protected against any overnight rain exposure during the work.

We clear the site of old material before we leave.

Flat Roofing Costs in Dereham

Flat roof replacement in Dereham typically costs between £70 and £120 per square metre, depending on the system chosen, deck condition, and the complexity of the detailing required. A standard single-storey extension roof of around 20 square metres would generally fall between £1,400 and £2,400 for a felt replacement, and somewhat more for EPDM given the material cost. These figures are a guide only; the actual price depends on what we find when we inspect the job.

Get an Honest Assessment of Your Flat Roof

If your flat roof is causing concern, the worst thing to do is leave it. Water damage spreads faster than most people expect. Call us to arrange a roof survey and we will give you a straight assessment of what needs doing, what it will cost, and which system makes the most sense for your property.