Things are progressing on our house renovation and I am excited to say we need to start thinking about the kitchen renovation which means finding out about flat roofs. Luckily for me, our friends at Hambro Roofing are flat roof experts and on hand to explain the options for flat roofing materials.

Hambro Roofing

Hambro Roofing is a family run flat roofs business established in 1978 by Steve Hammersley and has been trading for over 25 years. They are flat roofing specialists based in East London and cover all of the south-east. Their workforce consists of trained craftsmen in built-up-felt, mastic asphalt, single ply and liquid membranes such as Belzona, Kemper & Liquid Plastics.

Flat roofing materials

Having a flat roof worries me - will it hold, will it leak? Jon Hammersley, from Hambro Roofing, describes various materials available for installing flat roofs:

"Roofing felt is a term describing a roll of a base material which is impregnated and coated with bitumen or modified bitumen. High performance and reinforced felts have a polyester base material which doesn't split and is impregnated in modified bitumen.

There are 2 main methods of applying felt:

"The first and original method is "Pour & Roll". This is where bitumen is melted in a bitumen boiler, often called a pot, then using a ladle put into pouring cans ready to be poured onto the roof surface so that the felt can be rolled into the flood of bitumen.

"The second method is "Torch-on". The felt is manufactured with a layer of modified bitumen applied to the underside of the felt, this is heated up and melted using a gas torch to form a "flood" of bitumen at the base of the roll just like pour & roll.

"The bitumen on roofing felt should be protected from UV rays to prevent it from cracking. This protection is usually provided using mineral surfaced felt which is available in a range of different colours. Protection can also be provided using additional surfacing materials such as solar reflective paint, spa chippings or ballast. Promenade tiles or paving slabs can be laid as an option for walkways, balconies or patios."

"Mastic asphalt has a long and successful history as a waterproofing medium for flat roofs, basements and foundations as well as a surfacing material for floors, pavements, car parks and bridge decks. Originally it was a naturally occurring material which is a combination of bitumen and aggregate and comes in solid block form.

"Asphalt blocks are put into a pot or mixer and heated to approx 254°C for it become pliable. It is then put into asphalt buckets or wheel barrows, tipped onto the work surface and laid to existing levels using a purpose made timber float.

"Asphalt is naturally black and is available in a range of colours. Once applied and cured it should then be protected from the UV rays. This can be achieved using solar reflective paint, spa chippings or ballast. Promenade tiles or paving slabs can be laid as an option for walkways, balconies or patios.

"Mastic asphalt is in my opinion one of the best materials available for waterproofing flat roofs. In January 2008, UK mastic asphalt became the first industry in the world to achieve the CarbonZero standard. Anyone choosing advanced mastic asphalt systems to waterproof their project will get a totally CO2 neutral solution - ideal for eco friendly developments. The Mastic Asphalt Council's Carbon 100 initiative also means thousands of associated sub-contractors will have to meet the strict CarbonZero standard.

"Single ply membranes are rubber-like waterproofing sheets generally defined as either a Thermoplastic or Elastomeric. Single ply membranes may be installed fully adhered, mechanically fastened, loose laid & ballasted or as green roofs.

"More recent innovations such as coloured membranes and factory produced roof profiles have provided the opportunity to mimic the appearance of traditional roofing systems such as lead and copper.

"Single ply roofs don't necessarily need additional surface materials because they are compounded with additives such as UV stabilisers although paving, ballast and green roofs are regularly used.

"Liquid membranes are cold applied systems used for waterproofing and surfacing. They have a vast array of uses such as roofing, tanking, water features, wet rooms, balconies, car parks and decorative surfacing. Liquid membrane systems are also available as a decorative anti-slip surfacing product where hard-wearing protection is required without the need for waterproofing.

"Although Liquid membranes are cold applied, the use of hot works is sometimes necessary in order to dry the surface area ready for application. Application can be carried out using a roller, brush or a squeegy. Some systems require a curing period between stages of application.

"Surface finishes vary according to manufacturer being used. They range from a gloss top-seal to a quartz anti slip surface. There are also a variety of different colours available."

Our thanks to Hambro Roofing for their advice - for more detailed information on flat roofs and flat roofing materials contact Hambro Roofing.