EVOLUTION OF THERMOPLASTIC SINGLE PLY MEMBRANES 8 46 The first single ply waterproofing for roofs was a neoprene rubber membrane created in 1957. The early membranes were plagued by stories of fracturing and seam failures, as the advantages of reinforcing the membranes and modifying the formulations wasn't fully understood. Thermoplastic membranes are the mainstay of the roofing industry: PVC ( polyvinyl chloride), TPO ( thermoplastic polyolefin) which is also known as FPO, EIP ( ethylene interpolymer, CPA ( copolymer alloy) and NBP ( acrylonitrile butadiene polymer) are thermoplastic membrane materials. The early formulations of the thermoplastic single ply membranes have been superceeded by a new generation of engineered polymers that have addressed the concerns of the early failures. One issue was the problem of plasticizer migration. In the earliest days of PVC membranes, liquid plasticisers were added to the polymer mix to make them flexible. Over time, the plasticisers leeched out, leaving the membranes brittle and liable to fracture in cold weather. This problem has been virtually eradicated as advanced formulations ' hold' the plasticiser in the formulation to make it stable. A growing category of thermoplastic membrane is TPO which is designed to combine the durability and low- temperature flexibility of rubber with the proven performance of hot- air weldable seams. The membranes use rubber ( EPDM) and polypropylene ( PP) to form a polyolefin that does not require the use of liquid plasticisers to keep the membrane flexible. The membranes are reinforced to give puncture resistance while also adding some dimensional stability. TPO is not inherently fire or ultraviolet radiation resistant; because of this, fire inhibitors and UV protectants must be added to the mix before manufacturing the membrane. Less expensive TPO membranes may not contain as much of the additives as the better and more expensive formulations and may not last as long or obtain as high a fire classification. Tests have shown that TPO has excellent resistance to ozone and is algae- resistant, environmentally friendly and safe to install, it is highly resistant to tears, impacts and punctures with good flexibility to allow for building movement. Seam strength has never been much of a problem in thermoplastic membranes. Hot air welding fuses the two adjacent pieces together to form a monolithic seam which has proven to be a superb method of assuring a watertight join. Single ply membranes are a viable long term roofing solution and the product best suited to the project will depend on the charateristics that will address the building's requirements. No two buildings are exactly alike. Because of this, the membrane should be chosen, not because it has the lowest price, but because it's the best value for the money. bauder. ie Technical Guide Pages 59- 67

WELDING TECHNIQUES Hot air welding is the method used to securely join the laps of single ply membranes. There are principally two types of welding equipment, hand held and automatic machines; both require an electrical supply to the roof which is fed through a residual circuit breaker and is normally obtained direct from the mains supply or by generator where appropriate. The membranes will fuse together at temperatures between 380 - 500° C to provide homogenous joining as they cool. Thermofol PVC membrane can also be solvent welded. The solvent is wiped between the two pieces of membrane and chemically reacts to fuse the joint. HAND HELD EQUIPMENT This is used at all detailing on the roof for both Bauder FPO and PVC membranes as it allows for flexibility of positioning. It is not appropriate for the span of a large roof due to the slow application time. The equipment requires 110v power supply. Most hand- held equipment incorporates PID technology to give a continuously monitored temperature of between 390 - 500° C at the welding point. depending on membrane type AUTOMATIC EQUIPMENT These machines are larger and are used over the large span of the roof to deliver a homogenous join of the membranes. They incorporate a heavy roller which follows the welding point and applies pressure to the lapped membranes to ensure a secure weld. The machine requires a 240v power supply and is able to weld an average of 2.5 metres of lap join a minute. The machine automatically controls the temperature at the welding point, keeping it constant. The installation of Bauder Thermoplan FPO always requires automatic equipment on larger areas. 47 bauder. co. uk INSTALLATION TECHNOLOGY INSTALLATION TECHNOLOGY There are three principle options for attachment of single ply membranes, mechanical fastening, adhesive bonding and ballasting. Either installation method is suitable on new build or refurbishment projects; with consideration of the attachment method and additional loading to an existing structure discussed with your Area Technical Manager at an early design stage to ensure a satisfactory specification. MECHANICALLY FASTENED The mechanically fastened system allows the membrane to be fixed accurately and quickly; it is ideally suited for metal and timber deck constructions, though it can also be used on concrete decking. It has outstanding performance where there is a high risk of wind uplift and provides a secure, durable and economic installation. If tube washers are used with the mechanical fixings, the problem of cold bridging is avoided. The ability to unfasten the membrane also allows consideration to be given to recycling and life- cycle evaluation. ADHESIVE BONDING This method of membrane installation is ideally suited for very complex building shapes or where drilling and mechanical fastening is inappropriate, such as a concrete deck with a high proportion of stone or where the deck structure may be compromised by the drilling, or the visibility of the mechanical fixings is not desirable. The finished job is highly durable and avoids the problem of cold bridging. BALLAST This option for membrane attachment restrains the components of both warm roof and inverted roof systems. A suitable aggregate or paving should be specified that will be sufficient to resist wind uplift and flotation. In this situation, the single ply membrane needs to be protected from abrasion by the use of a separating layer. Hand Held Equipment CAD SPECIFICATION SUPPORT CAD DRAWINGS www. bauder. co. uk/ technical- centre NBS SPECIFICATIONS www. bauder. co. uk/ technical- centre TECHNICAL HELPLINE T: + 44 ( 0) 1473 257671 E: technical@ bauder. co. uk PROJECTS PORTFOLIO E: marketing@ bauder. co. uk W: www. bauder. co. uk/ media- centre SINGLE PLY SYSTEMS