When bitumen is modified by styrene-butadiene-styrene (SBS) polymers, it becomes elastomeric bitumen. A phase inversion takes place which converts the bitumen phase to the elastomeric phase with elastic properties from the Butadiene Rubber co-polymerised with polystyrene thermoplastic. The quality of SBS bitumen is determined by the quality and quantity of the polymers used and the type of bitumen as well as the effectiveness of the process used in mixing them.
How durable is Wrimco SBS membrane? How long will they last?
It is difficult to give a specific answer. All the other components of a roofing system, such as the insulation and the efficiency of its installation, play a great part in determining its life expectancy. Generally speaking (and under ideal conditions), we expect a Wrimco SBS modified bitumen membrane to remain waterproof for a period in excess of 30 years.
What are the advantages of SBS modified bitumen membranes?
Dimensional stability, Flexibility and elasticity, Excellent resistance to high temperatures, Great flexibility at low temperature, Excellent adhesion to deck, Dependable waterproofing and solid at the joints, Impressive longevity, Very good resistance to puncture and impact but easy to repair.
Is SBS modified bitumen compatible with other types of waterproofing like coal tar and plasticised PVC?While compatible with most substrates, SBS modified bitumen is chemically incompatible with coal tar and plasticised PVC but is fine for rigid PVC.
Is the presence of pounding water damaging to my roof?
In itself, pounding water does not damage Wrimco SBS membranes. At the same time, standing water can, in certain cases, cause sediment accumulation. This can result in a substantial loss of the granules, which protect the bitumen from UV rays, and hence may affect the membrane in this way.
What is the maximum weight that can be borne by a Wrimco SBS waterproofing system?
The maximum load on a Wrimco SBS roofing system must not exceed the compression resistance of the support panel, the membrane or the insulation when the base panel is installed directly onto the system, and to a maximum of 40 psi (275 kPa) ie. fibreboard = 30-40 psi.
Can I install Wrimco SBS membranes directly onto a timber deck?
Yes, Wrimco SBS heat welded waterproof membranes may be installed on plywood roofs by experienced applicators but not recommended for tongue and groove or plank roofs using pine or spruce or similar. Care must be taken that no sawdust or wood shavings are present.
Is it necessary to allow the membranes to relax before installation?
Allowing the membranes to relax before installation is good practice because it lessens the tensions created during manufacture. In all weather conditions, Wrimco strongly recommends that you unroll membranes a full 15 minutes before application, or to condition them with a torch when the temperature is below 5 degree C.
What is the minimum slope required on a roof?
In order to prevent granule loss, which can lead to premature aging of the membrane, it is important to have a minimum slope 1%. The slope must be consistent and lead toward the drains.
Can bird droppings damage membranes?
Yes, an accumulation of bird droppings can cause a loss of granules on the membrane. The granules protect the membrane's bitumen, so if they are removed due to cleaning, membrane deterioration is likely to follow.
Should membrane imperfections be repaired?
Certain minor defects do not require repair, while other more significant ones do. The decision to repair an SBS modified bitumen membrane, as with any other coverage roofing system, should be taken only after serious consideration, and must be based on the consequences to performance. Open joints, fishmouths at the overlaps, non-adhesion on large surfaces or surfaces where overheating has caused reinforcement distortion should be repaired as soon as possible.
On the other hand, anomalies such as minor wrinkles and blisters should be seen as inherent to the physical characteristics of these materials and their recommended methods of application. Patching a small wrinkle or blister for no reason other than to make look better is not justified in the majority of cases and, in general, the repair will look worse than the original imperfection.
What is the minimum curing time required before installing membranes on structural concrete?
In summer, a minimum maturation period of 7 to 10 days is recommended to ensure good adhesion to our membranes. This would be longer when the temperature is colder.
What is the optimum finish for concrete?
A wood float or light broom finish is ideal. Any laitance should best be removed by high pressure water jet or surface grinding to ensure adhesion under adverse conditions.
What about priming?
For plywood, blockwork and perfect concrete, priming is not really necessary but a light prime may assist. With ordinary concrete, priming is recommended and for any exposed roofs, it is important to use the proper SBS primer (SBS modified bitumen in Xylene).
Is it necessary to install a protection board on the membrane installed on a retaining wall?
Wrimco recommends the installation of a protection board to avoid punctures in the membrane during backfill. However, if the backfill consists of a fine substrate like sand, a protection board may not be required.
When bitumen is modified by styrene-butadiene-styrene (SBS) polymers, it becomes elastomeric bitumen. A phase inversion takes place which converts the bitumen phase to the elastomeric phase with elastic properties from the Butadiene Rubber co-polymerised with polystyrene thermoplastic. The quality of SBS bitumen is determined by the quality and quantity of the polymers used and the type of bitumen as well as the effectiveness of the process used in mixing them.
