Flat Roofing in Jersey

What the job involves

We start by assessing the existing deck, whether timber, concrete or an older board, and check the falls to make sure water drains rather than pools. Poor falls are one of the most common causes of premature flat roof failure, so we correct them with tapered insulation or re-decking rather than simply overlaying a new membrane on a flawed structure.

Installation involves fitting insulation above or below the deck depending on the build-up specified, then the waterproofing itself. Single-ply membrane is mechanically fixed or adhered and hot-air welded at the laps, while liquid membranes are applied cold and reinforced, which suits complex shapes, balconies and roofs with a lot of penetrations where welding sheet material is awkward.

Repair work involves locating the true source of a leak, which on a flat roof is rarely directly above the visible damp patch, then cutting out and patching the affected area or, where the covering has reached the end of its life, recommending a full strip and replace.

Common problems we fix

Flat roofs in Jersey face a specific set of issues linked to weather exposure and age of covering.

• Ponding water from inadequate or reversed falls
• Blistering and splitting on older torch-on felt roofs
• Perished upstands and flashings around parapet walls
• Wind-driven rain and storm damage lifting membrane at exposed edges
• UV degradation on roofs with long, unbroken southerly exposure
• Failed detailing around rooflights and soil pipes letting water track internally
• Moss and algae growth holding moisture against the membrane on shaded roofs
• Corrosion of old metal edge trims on coastal properties from salt air

Materials and standards we use

For new installations and full replacements we mainly specify SikaPlan single-ply membrane, which gives a durable, low-maintenance surface with a long service life and good resistance to UV and standing water compared with older felt products.

Liquid applied membranes are used where a seamless finish is needed around complex detailing, on balconies and walkways, and for overlaying sound existing substrates. Any adjoining slate or tile sections are finished to a high standard, and lead detailing is carried out in accordance with Rolled Lead Sheet Association guidelines.

How much does it cost in Jersey

Flat roof pricing depends heavily on the roof's size and its fall, since a larger area or one needing tapered insulation to correct poor drainage takes longer and uses more material. Access is another factor, particularly for roofs above extensions with limited scaffolding room.

The condition of the deck once uncovered can change the price too. Rotten timber or damaged boarding found during strip-out needs replacing before any new covering goes down. The choice between single-ply and liquid membrane affects cost, as does freight to the island for specialist systems.

We provide a free, written estimate for every flat roofing job so you can see exactly what's covered before work begins.