There is a myth surrounding the effectiveness of a flat roof covering. It is our belief that a flat roof covering, executed properly, will last a substantial period of time. At GNR we are able to offer flat roof coverings with manufacturers backed 15 year warranties. Such warranties are fully transferable should you then sell your property after installation.

However, our favoured flat roofing material has a life expectancy of 40 years and comes with an array of accreditations, associations, bells and whistles. The system that we favour for flat roof coverings is Sarnafil. Part of the Sika group has provided expertise in the commercial roofing sector for decades. Now, to assist with the growing popularity for flat roof coverings in the domestic market, their range of products has been adapted. Further information on the system and flat roof membranes on offer can be found here.

Such single ply membranes are suitable for an array of roof areas and can be coupled with either ventilated cold roof spaces or fully bonded warm roof constructions.

Suitable flat roofing applications

  • Orangeries
  • Balconies and roof terraces
  • Dormers, Porches and Bay Windows
  • Garage roof replacement
  • Conservatory roof¬†coverings or Gutters
  • Extensions

Insulating a flat roof

Warm Roof

A warm roof is one where the insulation is on top of the structure. As such the insulation should be fully encapsulated, the joints taped and sit onto a vapour control layer which is supported by a sub-deck. The diagram details a standard installation of a warm roof for a standing seam metal roof covering. However, the same detail would apply for a single ply flat roof.

Further, it would also be possible to adhere to the single ply membrane directly onto the insulation board, so long as the board had a suitable surface. This way, a fully bonded plyboard to insulation would not be required.

Cold Vented Roof

Where insulation is installed between the structure, or at ceiling level, it is necessary to ventilate a void above. This air space allows free movement of air to prevent dew point and subsequent condensation. Modern construction methods see a cold roof used less and less. However, should height and space be a consideration, using the structure to house the insulation is a good way of adding thermal efficiency to existing structures for instance.

Warm Roof Flat Roofing
Cold roof construction

Why Choose Sarnafil Single Ply for your flat roof?

Sarnafil, as a product, has a proven track record when used for flat roof applications. The rationale for choosing this particular single ply membrane over other flat roof systems is simple.

  • Life expectancy: According to the BBA certification process, Sarnafil membranes have a life expectancy in excess of 40 years.
  • Waterproofing: The membranes can stand ponding water without detriment to the product or its guarantee.
  • Wind resistant: Such flat roof membranes are fully adhered or mechanically fixed to the roof structure so offer maximum protection from wind uplift. Further, Sarnafil, on projects over 100m2, will take full responsibility for your wind calculations.
  • Stability: The Sarnafil membrane is thermally and dimensionally stable. Its performance remains unaffected by expansion and contraction. More so, the membrane is resistant to solar rays.
  • Safe installation: Fitting such a membrane does not involve flames. All joints or laps are hot air welded to form an extremely strong bond, stronger than the membrane itself.
  • Strength: All joints and areas where details are formed need to be permanently welded for strength. Steel details and a unique edge detailing system, Sarnametal, form solid, weather resistant interfaces on any flat roof area.
  • Maintenance: Such membranes are virtually maintenance free. Clearly you will still need to maintain outlets on your roof but should the product fail whilst under warranty, Sarnafil will cover the cost of both the materials and labour to correct the failure.
  • Standard Detailing: With Sarnafil, there is no reason to make things up on the job, all of the details have been pre considered and standardised. (see downloads Roof Assured Standard Details)
  • Installation times: Due to the nature of a single ply membrane, installation times are reduced versus traditional flat roofing applications requiring a build up of layers.

Single Ply vs GRP

For years GRP flat roof coverings or Glass reinforced plastic, have been a popular choice for domestic flat roof applications. However, form our significant experience in the roofing industry we strongly recommend that GRP is never used as a flat roof covering By its very nature GRP is, once set, a rigid substance. However, the same levels of thermal movement will be imposed on this substance as with any other roof covering. As a result, GRP has a tendency to delaminate from its substrate and split over time.

From our own experiences of using this product, the lifespan of a GRP roof is 7 years before catastrophic failure occurs.

Roof Assured Details

Click for more information

Flat Roofing Services offered by GNR

We are happy to provide householders with a comprehensive flat roofing service. Our trained operatives can replace your flat roof covering inclusive of a new deck, insulation and new membrane.

All interface work with existing buildings or roof areas comes as part of our service. Further, all flat roof applications will come with a manufacturer’s backed warranty.

Our flat roof projects

Enquire about a flat roof