Building Technology and Existing Basement Waterproofing - Assignment Example

Building Technology and Building Regulations Advice to the Board of Governors 1. Existing Basement Waterproofing Generally, the use of basement waterproofing method and type of construction is in line with the intended basement use and according to BS 8102:1990, basements that will be use for archive or similar delicate purposes requires a totally dry environment with strict control of moisture vapour. It therefore requires a method of waterproofing that can provide controlled condition, a drainage cavity to reduce water penetration, and water resistant concrete wall for sensitive environment which is Type C or drained protection (Cobb 2009, p. 307). Other basement waterproofing method such as ‘tanked protection’ is not recommended because it generally relies on the effectiveness of the waterproofing barrier and offers no protection against the ingress of ground water (Charlett 2007, p.57). Drained protection does not need the basement to be fully waterproofed since the system drains away the water through a drainage cavity to a sump where it collects and then pumped away (Walliman 2006, p.32). A typical drained protection: 2. Type of Pre-Cast Flooring System and its Benefits a. Hollowcore Slab This type of pre-cast flooring system typically requires ledger beams support since they are not design to transfer negative bending moments. The span of hollowcore slabs usually ranges from 7 to 10 metres (Brugelling & Huyghe 1991, p.285). The voids in the slab are designed to remove areas that do not contribute to the slab’s strength thereby reducing its weight. The benefit of this floor system aside from being lightweight is the usefulness of the voids as channels for cables, wiring, and plumbing (Spence 1993, p.241). They were also used for air distribution and thermal mass damping in indoor climate control (Bennett 2002, p.123). The system, particularly today’s pre-stressed hollow core precast slabs is suitable for one-way spanning flat slabs particularly for longer spans ranging from 9 to 18 metres. They are mass produced, cheap, reduce the volume of concrete required, and adequate for structural purposes (Bennett 200, p.123). Figure 2.1 – Hollow Core Slab Cross-Section\ b. Plate Flooring (Solid Wideslab) Generally used for residential buildings, solid wideslab system is made of internal mesh that allows notching and opes forming. A 2400mm wide and 200mm deep in situ screeded slabs which are suitable for upper floor application can span up to 7.5 metres and can come with painted finish and smooth self-finishing soffits. On the other hand, a 150mm to 200mm deep pre-screeded slabs that are often installed at ground floors are delivered self-finished and suited for poor sloping ground conditions where cut and fill is required (IPCA 2007, p.25). Figure 2.2 – 1500mm Solid Wideslab with mesh c. Double Tee Floor Slabs Double tee pre-cast floor slabs are useful for long span applications (Wakita & Linde 2003, p.151) and creating floors. Parking structures and industrial building often use double tee for upper floors because they can support large floor loads. It is easier to position and place during construction as it has two beams sections that makes fitting convenient. In addition, these two longtitudal beams make the system more stable and unaffected by storage or transport than other pre-case flooring system (Brugelling & Huyghe 1991, p.8). However, the weight and size of double tee make them difficult to transport thus impractical for small application (Datacad Llc 2004, p.545). Figure 2.3 – Double Tee Slabs 3. Steel’s Reaction to Fire and Suitable Fire Protection Structures made of steel are often subject to corrosion and although steel is non-combustible its strength may be weaken by fire particularly when its temperature reached 550 degrees centigrade (Barry 2007, p.47). Steel, like any construction material therefore requires fire protection as stated in the building regulations. The stress in steel beam for instance determines its load-bearing capacity and since the normal temperature of steel is about 593 degrees centigrade, it is likely to collapse when expose to fire. Moreover, it has the tendency to expand when it is heated thus other nearby structure can collapse when their steel framing pushed them (Cote & Bugbee 1988, p.149). In Approved Document B Vol. 2 (2007), steel elements of a structure should have 15 minutes fire resistance such as beams supporting concrete floors, free standing columns, wind bracing and struts. Moreover, steelworks in buildings must comply with BS 5950 for fire-resistant design (p.124). Another method of fire protection that can significantly ensure the integrity of steel frames are fire-resistant wall, fire spread and suppression devices such as internal fire-resisting lining and sprinklers (Approved Document B Vol. 2 (2007, p.62). 4. Minimum Stair Width for a 12 Storey Office Block Approved Document B Vol. 2 (2007) suggest that the width of stairs is dependent on the number of people that will use them during an emergency, the number of available stairs, and the type of evacuation strategy that will be applied. Determining the width thus require knowing the occupant capacity using floor space factors. Using Table 7 in B1 Section 4.23, the number of people that can be served by an 1100mm stair width in a 10 storey building is 580 and by linear extrapolation the figure indicates an increase of 40 people per floor. Therefore, the width of stair in 12 storey building should serve at least 660 or (580 + 40 + 40) people. Using the formula provided in paragraph 4.25: w= P + 15n-15/ 150+50n w = 660 + 165/ 150+600 w = 825/750 w = 1.1 metres stair width where; P is the number of people that can be served w is the width of the stair in metres n is the number of storeys served 5. Fire Safety Legislations for Buildings There are a number of relevant fire safety legislations in the United Kingdom and these include the Fire Precautions Act 1971 and the Fire Precautions (Workplace) Regulations 1997 and 1999 which are considered principal instruments on how fire safety is defined and enforced in the UK (Sullivan 2003, p.4). The Fire Safety and Safety of Places of Sports Act 1987 was a result of the inquiry made after the Bradford City Football Stadium incident in 1985 which made several amendments to the Fire Precautions Act 1971 (Thomson 2001, p.9). Under the Regulatory Reform (Fire Safety) Order 2005, fire risk assessment becomes a requirement for workplaces along with Building Regulations 2000 and guidance from Approved Documents (Ridley & Channing 2007, p.694). 6. External Access to Buildings for the Disabled Under the Disability Discrimation Act 1995 and the Disability Discrimination (Employment) Regulations 1996, buildings should make significant changes in their physical features to allow disable people to make use of their service (Approved Document M, 2004, p.7). Provisions of Approved Document M for external access of disabled people include a level approach to the entrance, ramp access not steeper than 1:20, stepped access with appropriate hand rail and level landing, removal of hazards on access routes, doors to accessible entrances, lifting devices, and others. a. Level approach and ramp access to entrances b. Stepped access with appropriate hand rail and level landing c. Protecting the Disabled on Hazards at access routes d. Effective width of doors to accessible entrance e. Lift for the Disabled Reference list: Approved Document B Vol. 2, Buildings and Other Dwellinghouses, United Kingdom, 2007 Approved Document M, Access To and Use of Buildings, United Kingdom, 2004 Barry Robin, The Construction of Buildings: Multi-storey buildings, foundations, and substructures, structural steel frames, floors and roofs, concrete, concrete structural frames, walls and cladding of framed building, Oxford: Wiley-Blackwell, 2001 Bennett D., Innovations in Concrete, London: Thomas Telford, 2002 Bruggeling A., Prefabrication with concrete, Netherlands, Taylor & Francis, 1991 Charlett Andrew, Fundamental Building Technology, Oxon, Taylor & Francis, 2007 Cobb Fiona, Structural Engineer’s Pocket Book, Burlington MA, Butterworth-Heinemann, 2009 Cote Arthur & Bugbee Percy, Principles of Fire Protection, US: Jones & Bartlett Learning, 1988 Datacad LLC, DataCad 11 Reference Manual, Connecticut: DataCAD LLC, 2004 IPCA, Precast Concrete, Dublin: Irish Precast Concrete Association, 2007 Ridley John & Channing John, Safety at Work, Oxford: Butterworth-Heinemann, 2007, Spence Williams, Architectural Working Drawings: Residential and Commercial Buildings, New York: John Wiley and Sons, 1993 Sullivan Dan, Tolley’s Fire Safety Training Manual, UK: Elsevier, 2003 Thomson Norman, Fire Hazards in Industry, Oxford: Elsevier, 2001 Wakita Osamu & Linde Richard, The Professional Practice of Architectural Working Drawings, New York: John Wiley and Sons, 2003 Walliman Nicholas, Self-build and renovation, West Sussex, John Wiley and Sons, 2006 Read More