Construction Journal Submission Report Week Nine: DETAILING VOLUME Nicole Tan 641433 Case Study Building: OVAL PAVILLION
SLOPED METAL DECK ROOF
LABYRINTHS AND DRIPS FLASHING 4825mm
DETAILING DECISIONS (that were not previously mentioned in Week Eight): The isometric drawings allow us to notice details in relationships and perspectives that were not as clear in the 2D drawing analysed in Week 8. Z-SHAPED PURLIN: From the isometric drawing, the purlinâ€™s characteristic and its relationship with the rafter is clearly visible. The Z shaped purlin is connected to the rafter whilst the roof sheet is connected to the purlin- this forms the roofing system of this section. This rafter and purlin system can be found at spaced intervals allowing the roof sheet to impose a more uniform load on each individual rafter. GUTTER: The gutter is a box gutter and is connected to the roofs using a gutter bracket. The gutter extends the length of the roof allowing water that falls off the roof to collect in the gutter and be redirected to the ground. Additional elements like the labyrinths prevent water from the roof from seeping back into the building.
ECONOMIC IMPLICATIONS PROTECTING: Waterproofing elements reduce water related issues this building can face like leakages and rotting. Thus, this allows the maintenance of the building to be cheaper as parts will not have to be regularly replaced. The sealant joint also provides a movement joint for the building to address the issue of minute movement from temperature changes, structural deflection and settlement. This reduces the degree of cracking and cost to repair these cracks. ECONOMIES OF SCALE: This section uses easily accessible and available materials and parts like box gutters, a timber framework and a brick veneer facade which is popular in Australian design. Thus this increases the cost effectiveness of the building as labour and skills are easily available whilst there is also a reduction in ad hoc members that need to be specially fabricated for the building (and hence will increase costs) The brick veneer facade is also straightforward in construction (wall ties are used to connect the facade with the timber frame) hence improving the ease of construction and decreasing inaccuracies and labour costs for assembling components.
WHERE AND WHY THINGS GO WRONG: AT THE WALL SYSTEM: As the wall cavity is a fairly large unit, water seepages from anywhere along the facade can affect a huge portion of the wall system as water can travel up and along the inner wall through capillary action. Thus, it is important that the flashing which extends through the cavity functions efficiently to ensure appropriate water proofing. AT THE GUTTER: It is evident through the isometric drawing that the gutter contains a fairly high surface area which can accumulate debris like branches and leaves from nearby trees. This can cause the gutter to be blocked and water to accumulate which not only increases the load imposed on rafters and roof beams but also encourages weed growth and overflowing (which can damage foundations) (Abrams 2000). AT THE OVERHANG: It is noticeable in the isometric drawing that there is a 10mm overhang which stretches across the brick veneer wall. This poses a water infiltration issue as water droplets can be directed back into the cavity through the underside of this overhang and consequently through the minute gaps in the mortar between the bricks.