Design free from limitations dictated by waterproofing installation
- Simple designs such as low parapet walls, no flashings, and no copings

1. Role of the flashings and corner coating
Asphalt is sensitive to heat, and when its temperature rises, it can change from a solid to a near-liquid. When asphalt is applied to concrete, its adhesion strength is reduced by heat: from 8.0 kgf/cm2 at 20 °C to 2.0 kgf/cm2 at 50 °C. With regard to the edge of the asphalt on the parapet lateral, asphalt creeps over the edge due to gravity acting on the asphalt itself (about 16 kg/m²) and the loss of adhesion due to hot sunlight (if the waterproofing layer is not fixed by other materials).

To prevent this kind of rainwater invasion due to the waterproofing layer drooping or other gaps originating from sagging, the waterproofing layer is anchored to the concrete frame using bricks and mortar. As shown in the lower right diagram, reliability is also improved by the application of a flashing that covers the edge of the waterproofing layer like an umbrella and prevents water from penetrating the edge of the layer. The drip edge is also set underneath the flashing.

In most cases, the edge of the waterproofing layer is mechanically fixed by aluminum angles or metal copings and is covered with asphalt coating. Because of this, there are numerous methods of application, such as no flashing being used plus extruded cement plates (or metal copings) and boards, without using bricks and concrete. (Lower right diagram) In this case, the edge of the asphalt on the parapet lateral is protected mainly from ultraviolet rays.

Because asphalt waterproofing cannot be firmly anchored to the frame concrete, the edge of the waterproofing has to be held down. The accuracy of this holding application varies with height of the asphalt on the parapet lateral from the deck to the bottom of the flashing. Measures shown in the diagram are those necessary as mentioned in books on asphalt waterproofing installation and waterproofing instruction manuals.