REVISION REVISION & EXAM PREPARATION 3 CLADDING 1

Past Exam Questions Aug 2010

Dec 2010

Aug 2011

Dec 2011

Aug 2014 Dec 2014

Answer Guideline Dec 2009

3- External Walls 1. 2. 3. 4. 5. 6. Main Performance requirements that need to be fulfilled by the cladding How they can be satisfied Fixings and technical issues Recommending an appropriate curtain walling system Connecting the cladding to the structural frame Sketching details

Main Performance requirements: 3- External Walls Main Performance requirements: 1. Structural stability: (withstand lateral loads, deflection, vertical loads from cladding itself, transfer of loads to frame), 2. Thermal insulation (slow heat loss or gain – U-values and cold bridging avoided), 3. Exclusion of moisture/weather protection (exclude wind, rain, snow), 4. Acoustic insulation (reduce sound transmission, level and type of external noise), durability (life expectancy of material and maintenance issues), Flexibility (adaptability and changing requirements), Aesthetics (building identity and expression of building use), 7. Fire resistance (prevent spread of fire to neighbouring buildings, allow safe escape from building, slows spread of fire within building) Ventilation (allows natural ventilation, Provision of openings), 9. Buildability, life expectancy, service capacity 15

What are the issues to be considered when selecting a type of cladding? Does the cladding provide the desired aesthetic appeal? How is the cladding system secured back to the structural frame? Is there a possibility of cold- bridging between the internal structure and the external face of the cladding material? How have all joints in cladding panels or units been detailed to prevent the passage of water or air from the external environment to the internal environment? Is there a need to incorporate windows or other opening units within a cladding system and if so, how will these be incorporated within the cladding without violating any of the above requirements. Is there a need to provide a form of solar protection to the external face of the cladding system in order to provide protection from excessive heat gain in summer months.

3a- External Walls How to achieve the performance criteria in curtain walls: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Use of neoprene seals and gaskets between mullions/transoms and glazing/ infill panels Thermal insulation in infill panels and the use of double or triple gazing in glazed areas Solar shading or blinds for excessive heat Low emissivity glass coatings / blinds Double or triple glazing / high quality neoprene seals Controlled ventilation louvers and dampers and/or opening windows - naturally ventilated building Use of neoprene seals and gaskets for air tightness in the case of air conditioned buildings Placement of cavity barriers where necessary together with selection of fire retardant materials in infill panels Panels secured within mullions and transoms bolted back to the structural frame at storey height intervals Ensure that span of panel does not exceed flexural strength requirement for likely imposed wind loading

Masonry Cladding Masonry support systems are required in buildings where the cladding exceeds 12 metres or 4 storeys. At this height traditional cavity wall construction is not possible. A system of support is installed to allow the masonry cladding to be supported from the structural frame.

Factors that must be taken into consideration when designing masonry cladding. Corrosion of support systems The durability of masonry cladding not only depends on the masonry and building details, but also on the quality of the anchorage system to the structure. The ties must be corrosion-resistant, if they are to give adequate structural performance and durability over 50 to 60 years. Masonry ties can be made corrosion-resistant with durable coatings such as zinc over mild steel, or by durable materials such as stainless steel or copper. Differential Movement The physical characteristics and environmental exposure of the cladding differ from those of the substrate or structural frame. Dimensional changes produced in the one may not be matched by those in the other. This gives rise to differential movement between the cladding and the structural frame. This can lead to distortion and damage of building elements or the structure. The risk of damage can be eliminated by introducing flexible joints between cladding units. These break up differential movement into small amounts.

Brickwork Facings

Composite panel

Curtain Wall – Stick System