WEEK 8 JOURNAL ENTRY
IN DETAIL
CONSTRUCTING ENVIRONMENTS
CHAN JOSHUA TIG HAY 638994
INTERROGATION OF THE DETAILING DESCISIONS Parapet capping is used to create a single-ply roofing system. It covers the parapet wall and is embedded into the pitched roof sheeting. The capping is then used to divert the water flow, which mainly come from rain and moisture, to the pitched roof and finally to the gutter which is connected to a pipe. (Ching 7.16) In addition, the capping is in black colour which matches the colour of the mullions in the curtain wall below it and this gives the wall an aesthetic value. A drip is used to prevent surface tension that causes water to cling to and flow along the underside of horizontal. (Ching 7.23) Opaque glasses make up glazing for the curtain wall. It acts as insulating panels to control heat flow through the glazed curtain walls and regulate temperatures of the building interior. (Ching 7.25) Batt insulation act as the thermal and acoustic insulation fitted between the walls. Pressure-equalized design is observed between the windows. It is critical in the detailing of curtain walls as the pressure difference between the outside atmosphere and the interior environment can cause rainwater to seep through small openings. (Ching 7.25) The design thus helps to facilitate pressure equalization between the outside and the inside to limit water penetration through the cladding. (Ching 7.23)
Parapet capping direct rain water to the gutters.
Pressure-equalized chamber CONSTRUCTING ENVIRONMENTS
Drip to prevent surface tension CHAN JOSHUA TIG HAY 638994
Composition 1. Steel purlins as the horizontal structural members that make up the roof framing, connecting the roof sheeting and the curtain wall. 2. Opaque glass as the material for the curtain wall and acts as a spandrel panel. 3. Aluminium mullions as the vertical element that divides the window units and is part of the curtain wall framework. 4. Metal parapet capping as a cover for the parapet wall. 5. Batt insulation made of fibrous glass and mineral wool. (Ching 7.41) 6. Roof sheeting with a 1 degree pitch. 7. Pressure-equalized chambers used in the curtain walls. (Ching 7.25)
Building process
Pros and cons
In this detailed section, the first element that is constructed first would be the steel purlins due its nature as a roof structural member that is load-bearing. The roof sheeting is then laid supported by the purlins. Lastly the curtain walls will be erected along with the parapet capping as these window systems are not load bearing.
This curtain wall detail is very efficient directing water flow and preventing water or moisture from seeping through the construction materials. The opaque glass and the insulation is also useful as it regulates the temperature of the building interior and prevent it from getting to hot. One drawback from this detail is that the materials used maybe costly. For example, the pressure-equalized design may require advanced technology and expensive manufacturing costs.
CONSTRUCTING ENVIRONMENTS
CHAN JOSHUA TIG HAY 638994
Sustainability and environmental analysis The detail has a low carbon footprint as steel is mainly used as the construction material. Steel is 100% recyclable and the use of finished steel can help improve energy efficiency which reduces the amount of carbon dioxide produced during the manufacturing process. (World Steel 2008) In addition steel has a very long life and thus saves a lot of embodied energy.
Economic implications of decisions The use of a parapet capping embedded into the roof sheeting to direct water flow instead of using vegetated roofing would be cheaper during the short term. However, there may be maintenance cost involved in the future.
Where and why things go wrong in this type of detail Problems are likely to occur in places where there are openings, in this case it will be the parapet capping and the glazing. The gap between the parapet capping and the wall maybe too close and insufficient spacing is allowed to prevent the occurrence of capillary action. (Ching 7.18)
CONSTRUCTING ENVIRONMENTS
CHAN JOSHUA TIG HAY 638994
REFERENCES Ching, F.D.K 2008, Buildng Construction Illustrated, John Wiley & Sons, New Jersey World Steel Association 2008, World Steel, Belgium viewed 3 October 2013, < http://www.worldsteel.org/about-us/history-and-objectives.html>
CONSTRUCTING ENVIRONMENTS
CHAN JOSHUA TIG HAY 638994