Flat roofs are a practical feature of many homes and buildings across Devon and Cornwall. They're commonly found on extensions, garages, porches, dormers, balconies and outbuildings, but like any part of a property, a flat roof will eventually need maintenance, repair or replacement.
When a flat roof starts leaking, blistering, cracking or holding water, choosing the right replacement system matters. There are several flat roofing materials available, including felt, EPDM rubber and GRP fibreglass systems. The best option depends on the existing roof, the building, the roof's size and shape, drainage, budget, and desired service life.
At Tamar Roofing & Building Services, we install and repair flat roofs throughout Plymouth, Devon and Cornwall. We're also trained installers of the Restec Flexitec roofing system, giving our customers access to a highly flexible, seamless GRP roofing solution. On eligible Flexitec roof installations, we can also provide a 25-year written warranty.
What is a flat roof?
Despite the name, most flat roofs aren't completely flat. They should normally be designed with suitable falls and drainage so rainwater can run towards outlets or gutters rather than remaining on the roof.
Flat roofs are particularly susceptible to problems when water can't drain properly. Ponding, blocked outlets, failed joints, damaged membranes and deteriorating decking can all eventually lead to water entering the building.
Common warning signs include:
- Water stains or damp patches on ceilings
- Persistent leaks after heavy rain
- Standing or ponding water
- Cracks, splits or blisters in the membrane
- Damaged or lifting edges
- Sagging sections of the roof
- Moss or plant growth
- Perished or brittle roofing materials
At Tamar Roofing, we offer flat roof inspections, repairs, and complete replacements across Plymouth and Devon, including roofs on extensions, garages, and other residential buildings.
Which flat roof material is best?
There isn't one roofing material that's right for every property. Different systems have different advantages, and a professional assessment should consider the existing roof construction before a recommendation is made.
| Flat roofing system | Key characteristics | Often suitable for |
|---|---|---|
| Felt | Traditional, cost-effective system | Garages, extensions and refurbishment |
| EPDM rubber | Flexible, lightweight and durable | Larger flat roofs and new-build projects |
| GRP / fibreglass | Seamless, tough and versatile | Garages, extensions, balconies and smaller roofs |
| Restec Flexitec 2020 | Flexible GRP system with overlay capability | New decks and suitable existing flat roof refurbishment |
Industry experts advise that typical lifespan estimates range from around 20-30 years for liquid waterproofing and torch-on felt to 40-50 years for some EPDM and GRP systems, although actual performance depends heavily on the specification, installation, environment and maintenance.
That's why comparing roofing systems purely on the initial price can be misleading. A cheaper roof that requires major repairs or replacement sooner may cost more over its lifetime. At Tamar Roofing, we recommend considering long-term durability rather than simply choosing the cheapest material available.
Why we use Restec Flexitec 2020 for flat roofs
One of the flat roofing systems we can install is Restec Flexitec 2020, a flexible GRP roofing system designed for both new decks and suitable existing roof surfaces.
Unlike traditional GRP systems that are generally associated with timber decking, Flexitec 2020 can be applied to a wide range of substrates, including felt, asphalt, concrete, existing GRP and PVC single-ply systems. Restec describes it as a highly flexible system that combines characteristics of GRP fibreglass and liquid-applied roofing systems.
For suitable roofs, this can provide an alternative to completely stripping the existing waterproofing before installing a new system.
However, an overlay isn't automatically suitable for every flat roof. Restec's installer guidance makes it clear that the existing roof must be assessed carefully and that defective or decayed insulation, decking, or substrate needs to be repaired or replaced before installing the new system.
That's one reason professional roof inspections are so important.
The benefits of a Flexitec flat roof
A seamless waterproof membrane
Flexitec creates a continuous reinforced waterproofing system without the numerous joints associated with some other roofing methods. The manufacturer describes the finished system as a tough and flexible membrane suitable for roofs and other applications.
Fewer joints can be particularly useful around awkward roof shapes, outlets, upstands and other areas where careful detailing is required.
Suitable for a range of roof surfaces
Flexitec can be used on a range of common roofing substrates, subject to assessment and the correct preparation. Restec specifically identifies felt, asphalt, concrete or screed, GRP and PVC single-ply among the substrates that can be coated.
This versatility makes the system useful for both refurbishment and new roof construction.
Fast curing
One of the great things about Flexitec is how quickly it cures. You can usually walk on it in about 30-60 minutes, depending on the specific application and conditions.
For homeowners, faster curing can mean less disruption during the roofing work, although the total project time still depends on roof size, preparation, detailing, weather and whether structural or deck repairs are needed.
Cold-applied system
Flexitec is a cold-applied roofing system, meaning it doesn't require the naked flame associated with traditional torch-on felt installation. This can be particularly useful where the roof is adjacent to other building materials or areas where hot works need to be avoided.
Can an old flat roof be overlaid?
In some cases, yes.
One of the attractions of Flexitec is its ability to be used as an overlay system. This can potentially avoid the unnecessary removal and disposal of an existing waterproofing layer when that roof is still suitable to retain.
However, this shouldn't be treated as a shortcut.
The existing roof construction should be inspected and, where appropriate, core samples taken to establish the roof build-up and condition. Wet or saturated insulation and defective or decayed substrates may require more extensive remedial work before installing a new waterproofing system.
There's another important point for homeowners: applying an overlay doesn't correct an existing fall or drainage problem. Standing-water problems will remain unless you change the roof design or drainage.
That's why a good flat roof replacement starts with inspection and diagnosis, rather than simply applying a new membrane over whatever is already there.
Why trained installation matters
The quality of a flat roof isn't determined by the product alone. Preparation, substrate condition, moisture levels, detailing, mixing, coverage, curing conditions and workmanship all have a major bearing on the finished roof.
Restec's Flexitec standard two-coat materials guarantee is only available after installer training. They also require installation records and product details for registration.
We're fully trained Restec Flexitec installers, so we can specify and install the system with the manufacturer's application requirements in mind and provide you with a manufacturer-backed guarantee.
That training includes assessing the existing roof, preparing the substrate correctly, using the appropriate primer where required and paying particular attention to vulnerable areas such as outlets, edges, upstands and junctions.
25-year warranty on eligible Flexitec roofs
For homeowners, the warranty is another important consideration when choosing a new flat roof.
At Tamar Roofing & Building Services, we can offer a 25-year written warranty on eligible roofs constructed using Restec Flexitec 2020. The precise terms of any warranty depend on the roofing specification and installation, so we'll explain what's covered as part of your quotation.
When comparing roofing contractors, it's worth checking warranty wording carefully. A manufacturer's materials guarantee and a roofing contractor's workmanship or system warranty aren't necessarily the same thing.
Restec currently offers a 20-year materials guarantee for its standard two-coat Flexitec system, available to trained installers, while its Flexitec Platinum system carries a minimum 25-year durability rating.
How to know whether your flat roof needs repair or replacement
Not every leaking flat roof needs stripping and replacement.
A professional inspection can establish whether the problem is caused by a localised puncture, failed joint, damaged flashing, blocked drainage or deterioration of the wider roof system.
In other cases, the membrane may have reached the end of its useful life, the decking may be damaged, or insulation may have become wet. In those circumstances, a full replacement may be the better long-term option.
At Tamar Roofing, our flat roofing service includes repairs, replacements and new flat roof installations across Plymouth, Devon, and Cornwall. We assess the roof first and explain what needs to be done, rather than automatically recommending a full replacement.
Get expert advice on your flat roof in Devon or Cornwall
Whether you have a leaking garage roof in Plymouth, an ageing extension roof in Devon, or you're planning a new flat roof as part of a building project in Cornwall, choosing the right roofing system can make a significant difference to the long-term performance of the building.
Restec Flexitec is a versatile option for suitable flat roofs, offering a seamless, flexible GRP waterproofing system that can be used for both new decks and refurbishment projects. Its suitability for overlays also makes it an attractive option where the existing roof structure is sound and suitable for retention.
As trained Restec Flexitec installers, Tamar Roofing & Building Services can assess your flat roof, recommend the most appropriate solution and provide a clear written quotation.
We cover Plymouth, Devon and Cornwall, with flat roof repairs, replacements and new installations available for homes, garages, extensions and commercial properties.
Need advice about your flat roof? Contact Tamar Roofing & Building Services to arrange a free roof inspection and quotation.