Common Felt Roof Problems and How to Fix Them

Felt roofing remains a durable and cost-effective option for many UK homes and businesses – but like any flat roof system, it’s not immune to wear and tear. Over time, weather exposure, poor installation, or lack of maintenance can lead to issues that compromise waterproofing and structural integrity.At Astral Roofing, our team has decades of experience inspecting, repairing, and maintaining built-up felt roofs (BUFR) across Hertfordshire and the surrounding areas. Below, we explain the most common felt roof problems and how they can be fixed safely and effectively.

Roof Leaks and Water Ingress

The problem:The most frequent issue with felt roofs is leaking, often caused by cracks, lifted seams, or unsealed joints that allow water to penetrate beneath the layers.Typical causes:

• Age-related deterioration
• Poor installation or sealing
• Ponding water weakening the felt
• Flashing failure around roof edges or skylights

The fix:A professional roofer will identify the leak’s source, dry the affected area, and apply a heat-bonded felt patch or new cap sheet. For extensive leaks, a sectional replacement may be required. Regular inspections can prevent leaks from spreading unnoticed.

Blistering and Bubbling

The problem:Blisters (air or moisture pockets beneath the felt surface) are a common sign of trapped vapour or poor bonding during installation.Why it matters:If ignored, blisters can burst, allowing water to seep into the roof deck and insulation, leading to more significant damage.The fix:Small blisters may be carefully cut open, dried, and resealed using a torch-on felt patch. Larger or widespread blistering usually indicates that the roof needs partial resurfacing or replacement to restore full waterproofing integrity.

UV and Weather Damage

The problem:Prolonged exposure to sunlight, rain, frost, and temperature changes gradually breaks down the bitumen in the felt, causing it to crack or become brittle.Typical symptoms:

• Surface cracking
• Faded or chalky appearance
• Granule loss on the cap sheet

The fix:Apply a UV-resistant roof coating or new mineral cap sheet to protect the surface. These coatings extend lifespan and help reflect heat – ideal for older roofs approaching mid-life.

Ponding Water (Standing Water After Rain)

The problem:Flat roofs must have a slight fall to allow rainwater to drain. Poor design, sagging timbers, or blocked outlets can cause ponding, which accelerates roof wear.Consequences:

• Increased risk of leaks and cracks
• Added structural stress
• Algae or moss growth

The fix:Improve drainage by re-levelling the surface, adding tapered insulation, or clearing blockages. In some cases, installing a new felt system with improved falls is the most effective long-term solution.

Cracking, Splitting, or Lifting Edges

The problem:Over time, felt may lift, shrink, or split, particularly around roof edges, joints, and flashings where movement and weather impact are greatest.Causes:

• Thermal expansion and contraction
• Poor adhesion or aged bitumen
• High winds loosening the edges

The fix:Re-seal affected joints using torch-applied bitumen and install new edge trims or flashings where necessary. For widespread edge failure, a new overlay system can provide a cost-effective refurbishment without removing the entire roof.

Moss, Algae, and Debris Build-Up

The problem:Flat roofs often accumulate leaves, moss, and dirt, especially around drainage outlets. This organic matter traps moisture and promotes deterioration.The fix:Schedule annual cleaning and inspections. Remove debris, clear gutters, and consider applying an anti-moss treatment. Preventative maintenance is the simplest and most affordable way to extend your felt roof’s lifespan.

Poor Previous Repairs or DIY Fixes

The problem:Many leaks worsen after inadequate patch jobs or temporary DIY fixes using mastic or cheap sealants. These solutions often trap moisture and cause more harm than good.The fix:Have the area assessed by a professional roofer. Astral Roofing’s experienced roofers will remove any failed materials, inspect the underlying deck, and perform a permanent, torch-on repair to restore proper waterproofing.

Preventing Future Felt Roof Problems

Regular maintenance and early intervention are key to keeping a felt roof in top condition. Astral Roofing recommends:

• Annual roof surveys to catch early signs of wear.
• Prompt repair of cracks or lifting seams.
• Routine gutter clearing to avoid water build-up.
• Protective coatings to guard against UV and weather damage.

These simple steps can add years to the lifespan of your flat roof and save thousands in future repair costs.

Professional Felt Roof Repairs

If you’ve noticed leaks, cracks, or other signs of wear on your felt roof, don’t wait for the problem to worsen. At Astral Roofing, we provide expert flat roof inspections, repairs, and maintenance for homes and commercial buildings throughout Hertfordshire and the neighbouring counties.Our fully qualified roofers use premium torch-on felt systems and high-performance materials to deliver lasting, watertight results.Request your free felt roof repair quote today and let Astral Roofing keep your property protected – whatever the weather.

For a lasting fix, Astral Roofing provides professional flat roof repair and replacement across Hertfordshire, Essex and London.