Construction Journal Submission Report Week Eight: IN DETAIL Nicole Tan 641433
ALUMINIUM FASCIA
Case Study Building: OVAL PAVILLION
FALL
METAL DECK ROOF
RIGID INSULATION
DRIP
JOINT SEALANT AND BACKER ROD BRICKWORK FACADE/MASONRY VANEER WALL
DRIP
CAPILLARY BREAK SLOPED GUTTER
FLASHING RAKED MORTAR JOINTS
GUTTER BRACKET
WEEPHOLE INTERNAL RAFTER
THERMAL MASS INSULATION
Constructing Environments Student Journal | Nicole Tan
WALL TIES
WATERPROOF MEMBRAENE (dotted line)
Page 1
DETAIL OF ROOF SECTION
ROOF SECTION DETAIL IN RELATION TO THE PLANT ROOM
Constructing Environments Student Journal | Nicole Tan
Page 2
DETAILING DECISIONS: The detail studied here is part of the roofing system of Oval Pavillion’s Plant Room. FLASHING AND WEEPHOLES It is clear from this detail that this section of the building utilises a cavity wall system and hence require an internal drainage system (the cavity flashing and weep holes) to remove any moisture that penetrates the cladding (Ching 2008). The weep holes are simply open purpens in the brickwork. SEALANT AND BACKER ROD The sealant functions to neutralise one of the four predominant forces- air pressure. It ensures that the water droplets are not sucked into the building through the change in air pressure and hence ensures the internal cavity remains dry. The backing rod enhances the adhesion in the joints through the rod’s dimensional stability in withstanding compression and tension forces whilst it also repels moisture and assists in insulation (Wrimco Waterproofing n.d.).It is important that the sealant is durable and contains both adhesive and cohesive strength (Ching 2008). RAKED MORTAR JOINTS These joints are less water resistant than other joint designs (like the ironed joint) as it incorporates ledges where water droplets can accumulate. Thus, in order to decrease water penetration, the mortar can be further compacted to reduce roughness and inconsistencies of its edges (Krogstad 2007). GUTTERS, DRIPS, LABYRINTHS AND CAPILLARY BREAKS The gutters and drips keep water away from openings whilst the capillary breaks and labyrinths assists in neutralising surface tension forces of water. The interlocking seams of the drip in this detail also form a labyrinth that prevents the passage of water into the internal areas (Ching 2008). Utilising slopes in the gutter and roofs can also help shed the rainwater from the roofs. In this case, a fascia gutter is used and it can be constructed so that the edges of roof sheets are concealed to increase water carrying capacity (Fitzgerald 2010).
Constructing Environments Student Journal | Nicole Tan
Page 3
SPANDREL FLASHING Flashing is a thin continuous sheet of metal which is installed to prevent the passage of water into a structure from an angle or a joint (Ching 2008). In this case it would be the joint between the fascia and the facade or post. This flashing is a type of spandrel flashing and is concealed within the cavity. Water caught along this flashing is diverted to the weepholes in the masonry facade wall which is more susceptible to water penetration (Ching 2008). INSULATION (BLANKET AND RIGID) The insulation is included to control the transfer of heat and prevent excessive heat loss in winter and heat gain in summer (Ching 2008). The type of insulation used in this section includes Batt/Blanket Insulation which is installed between the studs and Rigid Insulation which is applied below the roof deck.
Constructing Environments Student Journal | Nicole Tan
Page 4
BUILDING PROCESS AND COMPOSITION:
STEEL FRAME
Bolts are used in the rigid joints TIMBER STUDS AND NOGGINS
DIAGONAL BRACING
The construction of the Oval Pavilion is still underway. The insulation will be placed within the grids created by the studs and noggins whilst a water proof Sisalation membrane will also be placed on the external side of the wall system to reduce air and water flow. The brick facade will be attached to this wall system.
Constructing Environments Student Journal | Nicole Tan
Page 5
ENVIRONMENTAL SUSTAINABILITY: From the two sections above, it is clear that the materials used (concrete, steel and timber) contain fairly high embodied energy. If the timber is sourced from a plantation or is recycled, it will assist in increasing the sustainability of the building. Locally sourced timber and steel will also reduce the carbon footprint of the materials as it would decrease transport energy and costs. Furthermore, if the rainwater collected from the roof system (detailed above) can be recycled and reused within the building, it will dramatically decrease the environmental impact and economic costs of the building. The raked mortar joints also have a negative environmental impact as the mortar smeared on the recesses of the bricks are cleaned with a highly acidic solution. This causes issues like groundwater pollution and it also increases water penetration due to etched joints (Krogstad 2007). Furthermore, maintaining and cleaning the masonry wall can also involve processes which can have a negative environmental or health effect. For example, the use of highly acidic or alkaline solutions or use of organic solvents (which can cause burns and are toxic) (Heritage Victoria 2001).
WHERE AND WHY THINGS GO WRONG: AT THE GUTTER SYSTEM: The most susceptible area of this section is the gutter system. Water can impact heavily on a building system therefore if the gutter is inefficient in directing the water from the roof to the ground, the loads from accumulated water during periods of heavy rain can cause the gutter or the roof to deflect under the load which will cause leakages. Thus, the gutter needs to be constructed to accommodate overflow whilst sealants need to be properly employed in areas with openings or at joints. AT THE MASONRY FACADE: Water flows into the cavity through the separations between the mortar and the bricks due to bond separations, minute cracks and voids. Furthermore, absorption also occurs through the bricks and mortar and this can cause water intrusions within the building which will cause the weakening of other members and materials (Building Diagnostics Group 2013).
Constructing Environments Student Journal | Nicole Tan
Page 6
REFERENCES: Building Diagnostics Group 2013, Building Diagnostics Group, Atlanta, viewed 25th September 2013, < http://www.bdgusa.com/masonry-wall-drainage-testing.html> Fitzgerald J. 2010, Home Improvement Pages, Australia , viewed 25th September 2013 <http://www.homeimprovementpages.com.au/article/What_is_a_Fascia_Gutter> Heritage Victoria 2001, Department of Planning and Community Development, Victoria, viewed 25th September 2013, <http://www.dpcd.vic.gov.au/__data/assets/pdf_file/0020/36830/CleanMasonry.pdf> Krogstad N. 2007, Hanley Wood Media, Washington DC, viewed 25th September 2013, <http://www.masonryconstruction.com/audiovisual-equipment/raked-mortar-joints.aspx> Wrimco Waterproofing n.d., Wrimco Waterproofing, New South Wales, viewed 25th September 2013, <http://www.wrimcowaterproofing.com.au/index.php?p=1_40>
Constructing Environments Student Journal | Nicole Tan
Page 7