EPDM Roofing Hampshire

Bubbling, blistering, or peeling felt across the roof field indicates that moisture has become trapped within the covering and that the bitumen layers are failing. As felt ages, it loses its flexibility and can no longer accommodate the thermal movement of the deck beneath it.

EPDM rubber is well suited to replacing old felt in these circumstances, as it adapts to both cold winters and hot summers without cracking. A single, seamless sheet also removes the lap seams that are the most common failure points in traditional felt builds.

Open seams where two sheets meet at a lap indicate that the adhesive has failed and the membrane is no longer watertight. Traditional felt roofs have multiple lap seams that can catch water and allow ingress to develop over time.

EPDM seals against rain, frost, and UV damage in a single piece, removing the failure point inherent in old bitumen builds. Most domestic extensions are covered with one continuous sheet — no field seams, no weak joints.

Soft spots underfoot suggest that water has penetrated the old covering and is saturating the deck timbers beneath. We probe every square metre with a moisture meter and screwdriver; readings below 18% confirm the deck is sufficiently dry for EPDM to be installed over it.

We replace any soft boards, punch loose fixings 2mm below the surface, and check perimeter timbers for rot before bonding the new membrane. A felt covering can appear intact at the surface while EPDM blisters within months over a wet deck, which is why verifying dryness at this stage is critical.

Brown staining on the ceiling below the roof indicates active water ingress through the flat roof covering. Water tracks down through the deck and into the room, damaging plaster and potentially encouraging mould growth.

EPDM bonds to timber, concrete, and PIR insulation boards, providing a robust waterproof layer that arrests ingress effectively. The membrane remains watertight long after felt would have failed, protecting the interior from further staining.

Standing puddles remaining on the roof 48 hours after rain has stopped indicate that the deck either lacks sufficient fall or has deformed, causing water to pond. EPDM can tolerate short ponding of up to 48 hours without deteriorating, which traditional felt cannot reliably match.

Decks falling at 1:80 drain to outlets at one corner, while decks with a fall below 1:40 require tapered insulation or firrings to create proper drainage. The membrane performs reliably through UK rain, wind, hail, and frost without cracking, blistering, or losing seal strength.

We begin every job with a free site survey from a director, measuring the deck, photographing defects, and recording moisture readings. The deck must fall within 3mm of flat over a 2-metre run to drain properly.

We assess deck size, pitch, exposure, and the build-up below to determine the appropriate EPDM specification. Sheet thickness, insulation grade, and edge detail are all decided on the basis of these four factors.

The old covering is lifted and removed, and any soft boards are replaced with new timber. We sweep the deck thoroughly twice to ensure all debris is cleared before preparation begins.

We vacuum the deck a second time before primer is applied, so no dust or grit remains that could prevent proper adhesion. On a tired extension, OSB sheets may need to be replaced if the original deck has been compromised.

The surface is primed and allowed to dry, with careful checks to confirm that no dust or grit remains that could prevent the membrane from bonding correctly. Moisture readings below 18% confirm the deck is sufficiently dry for EPDM installation.

EPDM roofing is a single-ply synthetic rubber membrane bonded to a flat or low-slope deck. Thorough deck preparation is essential to ensure the membrane adheres correctly and achieves a service life of 40 to 50 years.

The EPDM sheet is rolled out across the deck, allowed to relax fully, and then bonded down with adhesive. On most domestic decks we fit a 1.2mm sheet across the field, while larger commercial-style decks step up to 1.5mm.

The sheet seals against rain, frost, and UV damage in a single piece, flexing through wide temperature swings without splitting. A south-facing roof can swing from cold overnight lows to hot summer surface temperatures, and the membrane accommodates that movement without degrading.

The perimeter is dressed into kerb trims, drip edges, and termination bars, with the membrane locked into aluminium trims around the full edge. We bond the membrane to the deck first and then dress it into each trim in sequence.

Coastal Hampshire jobs are finished with marine-grade stainless steel fixings, while aluminium kerb is used on sheltered inland sites. All new installations are covered by our 10-year workmanship guarantee.

EPDM works best on flat extensions, garages, dormers, porches, and balconies — anywhere the deck pitch remains below 10°. The system is well suited to most domestic flat roof replacements across Hampshire.

Shed roofs, summer houses, and garden offices all take the same membrane, and a single sheet can wrap an L-shaped extension without any field seams.

Common Hampshire applications include:

• Detached garages and outbuildings
• Single-storey rear extensions
• Dormer cheeks and dormer roofs
• Porches and bay window tops
• Garden offices and workshops

The membrane bonds to timber, concrete, and PIR insulation boards, and that adaptability suits most domestic build-up types.

EPDM edges are locked into aluminium kerb trims, drip edges, and termination bars. We bond the membrane to the deck first and then dress it into each trim, ensuring the edge is fully secured before moving on.

A single continuous sheet covers most field areas; larger roofs use factory splice tape to join sheets. Each seam receives a cleaner pass, primer, and a firm roller pass to achieve a full bond.

The correct metal for perimeter trim varies by location in Hampshire:

• Marine-grade stainless steel on the coast
• Aluminium kerb on sheltered inland sites
• Lead apron flashings at chimneys and abutments

Parapets are dressed with a separate flashing strip welded to the field sheet. Most leaks on poorly fitted EPDM roofs can be traced back to inadequate joint preparation rather than a failure of the membrane itself.

EPDM handles UK rain, wind, hail, and frost without cracking, blistering, or losing seal strength. A fully bonded sheet can tolerate short ponding of up to 48 hours without sustaining damage.

Full deck bonding resists wind uplift, and we mechanically fix the edges into the substrate for additional security. On most storm callouts to coastal flat roofs, felt seams are found to be lifting — not rubber membranes.

Coastal properties can retain their EPDM covering through severe storms, and branches dropped onto the rubber surface will deflect without causing damage. The membrane carries hail resistance ratings that exceed both felt and GRP.

EPDM sits above the deck and insulation. The membrane provides waterproofing but does not itself warm the room below, so the rubber is paired with 100mm to 150mm of PIR insulation on most builds to achieve the required thermal performance.

A warm roof places the PIR above the joists, which eliminates the condensation risk within the build-up. U-values achieved are typically around 0.18 W/m²K, meeting Building Regulations Part L.

A cold roof requires vented eaves and clear airflow beneath the deck. Because the rubber membrane is vapour-tight, warm humid air from the room must not be allowed to reach the cold deck; a vapour barrier is fitted to prevent that. Most failed cold roofs show timber decay resulting from missing ventilation rather than membrane failure.

EPDM laps a minimum of 150mm up every wall. A trim bar fixed at 300mm centres locks the upstand in place, with termination bars, primer, and compatible sealants completing the detail.

Around windows and rooflights, the sheet is dressed under the cill DPC and returned up the reveal, with the frame returning over the dressed rubber. A separate lead apron is fitted over the upstand bond at chimneys.

On a kitchen extension, the membrane can be run under a new patio door threshold to maintain a continuous waterproof line. We check cavity wall ties before bonding to ensure that any dropped mortar has been cleared, which can otherwise compromise the upstand bond.