1. How many layers of membrane do we need for exposed application?
<span rgb(90,="" 90,="" 90);="" font-family:="" tahoma;"="">The industry recommends a 2-layer membrane system. The mineral surfaced or ‘slated layer is known as the cap-sheet. The Cap-sheet will protect the first layer of membrane, which is the actual waterproofing layer in this system.
2. In case of a two layer system; in which direction should we apply the second layer, and why?
Due to the non-isotropic nature of some reinforcement cores, it is recommended that the membranes be laid in the same direction but with staggered side-lap and end-of-roll joints. This practice will reduce stress on the membranes.
3. What are Modified Bitumen Membranes?
Modified Bitumen Membranes are waterproof sheets made by saturating and coating a robust reinforcement core material such as non-woven polyester, fiberglass mat or a combination of both with an impervious compound of polymer modified bitumen. The membranes produced are of pre-determined thickness and finished with a choice of surfacing materials suitable for most waterproofing applications.
4. What are Modifiers? How do they work?
Bitumen or Asphalt in its natural form is highly unstable and has limitations for use. In winter the bitumen will crack and in summer it will turn soft and run. In order to stabilize bitumen so that it remains flexible at lower temperatures yet stable at higher temperatures, polymers are used to modify its structure. This is done by combining under controlled conditions polymers, anti-oxidants and stabilizers to form a modified bitumen compound. Such compounds remain flexible at temperatures below -20°C and stable at higher temperatures of up to 150 °C. The most important modifiers are APP (Atactic Polypropylene) and SBS (Styrene-Butadiene-Styrene).
5. What is APP?
APP (Atactic Polypropylene) are thermoplastic polymers which when combined with asphalt under controlled conditions form a matrix that enables the asphalt to remain stable in conditions of high heat while remaining flexible at lower temperatures.
6. What is IRMA Roof?
An IRMA Roof (Inverted Roof Membrane Assembly) places the roofing membrane, directly on the deck. An Insulation layer, which is usually some type of extruded polystyrene is then placed over the roofing membrane. In many cases a separation layer is installed over the insulation followed by ballast which comprises smooth rounded stone or rock to keep the insulation from floating or blowing away. The separation layer keeps the rocks from getting under the insulation boards. This type of roof has some advantages. The roof membrane is shielded from UV attack and foot traffic. The roof membrane is also kept at a lower than ambient temperature which extends the life of the membrane.
7. What is Ponding?
Ponding is the accumulation of water on a roof surface for more than 24 to 48 hours. The stagnant water turns foul after reacting with atmospheric pollutants, damaging the bituminous surface it accumulates on as well as producing a foul odour. Recommended application procedures require ponding to be eliminated from the roof surface in a relatively short period of time. Adding drains can eliminate ponding. In the design phase ponding can be eliminated by creating a positive slope-to-drains throughout the deck, by using tapered insulation or by the addition of more drains
8. What is SBS?
SBS (Styrene-Butadiene-Styrene) are elastomers, when combined with asphalt provides elasticity, flexibility at very low temperatures, while retarding the ageing process. SBS-modified bitumen sheets that do not have factory applied granule or foil surfacing need some form of field-applied ultraviolet protective coating.
9. Which application system is the best for the life of the membrane?
The loose laid system is the optimal method for application, as it reduces the stress and fatigue on the membrane; thereby extending the service life of the the membrane system.
10. Why do we test low temperature flexibility in the Gulf region?
<span rgb(90,="" 90,="" 90);="" font-family:="" tahoma;"="">A membrane exhibiting good flexibility at lower temperatures is a sure sign of a waterproofing membrane made with a well modified bituminous compound. Such a superior compound will retard the natural ageing process of the membrane; and remains flexible for a minimum period of 10 years.