‘Flat roof’ in itself is a misnomer as all roof designs require a pitch to one end or one side to allow the rainwater (top-water) to be directed into a gutter or it would simply spill over at any point on the exposed elevations. To form the pitch a triangular strip of timber known as a ‘firing’ is introduced along the length of the rafters and the deck is then installed, for example 18mm ply-wood. This operation transforms the deck from a flat roof to a slightly pitched roof, the degree of the pitch is dictated by the size of the firing e.g. 150mm at the front tapering to zero or perhaps 130mm – 20mm. Next, triangular timbers are installed on the edges (except the gutter end) to form an upstand to prevent the rainwater cascading over the edges and is directed to the gutter end of the roof – these are known as ‘tilt fillets’ or ‘arris edges’.
Now we need to look at a raincoat for our new roof and there are many different options to choose from all with different pro’s and con’s…. so here we go.
BUILT UP ROOFING cover was used extensively for decades and served a purpose but was notably unreliable unless installed under perfect conditions.
MODIFIED BITUMEN ROOFING systems can be installed in several ways although those requiring hot bitumen and the use of a blowtorch in the operation – not a good idea on a timber roof. Although still used with much improved materials, it is labour intensive and not the most economical solution and installation is always dependent on weather conditions. Life expectancy 10-15 years
GRP (fibreglass) is a fairly new product in the roofing industry and should not be confused with the GRP used in boat and car building. This system is lightweight, good for irregular shape roofs to avoid seams and joints and it is simple to repair. The downside with this system is that is not good for large areas as expansion and contraction rates can be excessive and the overall installation costs are greater than other modern options Life expectancy 20-30 years
EPDM (ethylene propylene diene terpolymer) This system has been around for quite a long time but for some reason ignored in favour of the above. In recent times EPDM has really become the preferred cover for a low-slope roof. It is a single rubber membrane that covers the complete roof and it can be supplied in one wide sheet to most popular lengths, therefore removing the need for seams and joints. The roof deck is simply spread with the recommended adhesive and the rubber sheet is bonded in no time. Areas in excess of 100m2 require a special spray adhesive. If joints have to be made, it is a fairly simple operation again using the manufacturers recommended over-lap adhesive. Should any damage occur, it is an easy repair – just like mending a puncture in a bike tyre inner tube. A good supplier will sell you the installation kit that includes tilt-fillets, even a roller and scissors are included in some DIY kits. This is an economical, fast and reliable method of low-slope roof cover, hence its popularity. Life expectancy up to 50 years.
MAF URBAN ROOFING This definitely the new kid on the block and one to watch! MAF is a spray system made from recycled tyres and ecological binders. It is available in 4 popular colours and is UV resistant. The product is applied by cold spray and is flexible, so no cracking occurs and it is fire resistant -in fact, it is self-extinguishing! It is non-toxic and joint free. A further added benefit of this system is its insulation properties that will contribute to a thermal calculation where required for building regulation compliance. It is quite an economical solution compared to most other modern flat roofing options MAF URBAN MARQUE LTD are authorised installers of the MAF URBAN rubber roof system.