Please enable JavaScript.

Coggle requires JavaScript to display documents.

3E - ECONOMICS OF BUILDING DESIGN, The limited size of the site will limit…

- - - - z
    - - The ratio of wall to GFA does not change in Tandem with the size of building
    - - It is more economical to construct a big building than a few small
        buildings, which have same gross floor area with the big building
        because cost such as external wall construction and related works such as piping works, roofing installation and etc will decrease
      - The cost does not rise in proportion with increase in size
- - - - the engineer must determine the type of foundation suitable for different buildings.
    - - The sloping site will affect the design, use of step foundations, additional excavation might be required for this site. The number of bricks used for work below ground level at the sloping sites will be increased.
      - The use of basement floor or split level construction can reduce the filling words.
      - Sloping site will affect the cost.
    - - Inferences:
        The lower the load bearing capacity, the higher the changes of cost for foundation.
        Example:
        For soil with a safe bearing capacity of 600kN/m2, the load can be transferred directly to the pad foundation. But, for the soil that has only a safe bearing capacity of 60kN/m2, it requires a large foundation. This is uneconomical, impossible and impractical to provide. Due to this, a pile foundation is used to obtain the strength required.
        Changes in the foundation system will cause drastic increase in cost.
    - - The type of soil will influence the materials used in foundations, The existence of sulphates in the soil for example will cause the cost of concrete works and brickworks more expensive. Sulphate also affects the construction cost of ground floor. To summarize cost will be expensive if there is sulphates in the soil.
  - - - Maintenance also differs according to types of construction.
      - Parts of the external walls can be constructed using curtain walling or infill panel constructed of materials other than bricks or blocks. The initial construction cost for this type of walling is more expensive than for brickwall but the cost of the window element may be reduced if glass is used.
      - The external walls can be constructed from load bearing wall or infill panel. A load bearing brickwall may need stronger bricks compared to brick infill wall panels.
      - If the external walls consist of a large proportion of basement wall, it will increase the cost of the wall because of the need for waterproofing. In most cases, basement wall construction is more expensive than normal external wall, whether it is constructed of bricks or concrete.
      - The type and size of openings in a wall influence the element cost.
      - The type of external cladding used affects the load borne by the frame, which will determine the structure size whether large or small. in some cases, the load may affect the foundation.
      - The shape of the buildings influences the area and cost of external walls. If two buildings have similar GFA but one has a square shape and the other a rectangular shape, the one that is rectangular will have a bigger external wall area.
  - - - The column and beam frame system, as well as the portal frame system, are suited for structures such as warehouses and factories.
      - For a simple building, a framed structure is not needed. The construction of a load bearing wall structure can be used as an alternative.
      - A single storey building will typically have a framework consisting of colums and beams that support the roof structures.
    - - Consists of frames made of stanchions or columns and beams.
      - It is not just a concern in terms of stanchion and beam span, but the thickness and kinds of slab applied for the floor may also change as the beam span change.
      - The floor loading will affect the optimum beam spacing.
      - For example, building A and B have the same space area and size but the floor span of A less than B, if the constructions of both buildings are the same, the thickness of floor B is probably more. This means the weight of floor B is heavier.
    - - Frame are generally build from steel and concrete. Timber, aluminium other types of material also can be used used.
      - When choosing the frame to be used, several factors affect the cost :
        
        The time taken to erect the frame will have an effect on the cost of preliminary works.
        
        Large components of steel and precast concrete need a bigger crane to do hoisting works. (not necessary for building used in situ concrete).
        
        The protection of the frame against fire needs to be considered.
        
        The supply and installation of steel frame and precast concrete usually cost more than in situ concrete.
        
        A better safety factor is allocated to concrete frames compared to steel frames due to supervision at the factory.
    - - Precast Concrete Frame
        
        Precast concrete is concrete units shaped and made earlier to fulfill both the architectural and useful function.
        
        Offers a variety of quality finishes and normally does not require the final finish after installation.
        
        Precast concrete is a dry-type construction and requires a short period.
        
        Type of construction that is expensive.
        
        Need special transportation especially if the site is far away from the factory.
        
        Need a good component jointing system during the installation.
        
        Needs to be designed carefully so that the maximum use of plant and formwork is achieved
      - Steel Frame
        
        Steel has very high comparison to its weight, makes its suitable for many uses.
        
        A single-story steel structure for use as a warehouse, workshop, or factory can be constructed utilising a variety of standard systems, which often include both a truss and column system as well as a portal frame system.
        
        More flexible for a grid system.Suitable for imbalanced grid formation and long span because steel is light. Changes in the design not influenced cost as no formwork is used.
        
        Suitable for land that is sensitive to settlement and movements. A steel structure can accommodate these movements.
        
        Advantage- Reduction in size of the structure
      - In Situ Concrete Frame
        
        The construction cost of in situ concrete frames is lower than the steel frame for the high rise building and flats
        
        For a building with short spans - more economical and suitable to be constructed using the concrete frame, as the columns do no support.
        
        For buildings with large spans - the weight of the concrete frame is is higher compared to the load that it will bear because of increase in the size of structures.
        
        Economical advantages of using a concrete frame is through:
        
        The use of precast concrete allows the building to be completed earlier. In situ concrete needs, more time to mature and this will add to the overall construction period.
        
        The use of standardized formwork for columns and beams.
        
        The use of formwork up to a maximum of four to six times. The formwork has to be designed so that the use of labor can be reduced whether to erect or strike the formwork.
        
        The concrete frame is suitable to be used for buildings that have simple plan shapes and standard size of sections to enable the repeated use of formwork to reduce cost
  - - - Method of manufacturing
        (a) standard or custom-made for certain construction
      - The performances like weatherproof, ventilation and quality of manufacturing
      - Material used
        (a) Timber = easily damage by fungus.
        (b) Stainless steel = expensive
      - small size windows = the cost /m2 GFA high
      - The types of glass and ironmongery is used
      - The type of windows
    - - Vertical Pivot
      - Horizontal Pivot
      - Top Hung Casement
      - Louvre
      - Double Hung Sliding Sash
      - Horizontal Sliding Sash
      - Side Hung Casement
      - Fixed Light
  - - - A house's timber floor is constructed of timber joists spaced approximately 400 to 450 mm apart.
      - The joists' size depends on the floor's span. The smaller the span, the smaller size of the joists.
      - The larger the floor spans, the more some form of strutting requires to provide additional strength.
        
        The form of strutting needed in order to provide additional strength will increase the total cost.
    - - The load they can bear changes depending on the type of use and the floor span.
      - A strong in situ concrete floor is heavier than hollow pot floor in order to carry similar load and span
      - Solid in-situ concrete floor is heavier than hollow pot floor in order to carry similar load and span. However the costs of laying hollow pots is higher than in-situ cocrete floor costs.
      - Hollow precast concrete floor
        
        Can be installed in all weather and sometimes may not be suitable for in situ concrete
        
        The use of precast units may not be suitable for irregular shapes and areas that are too small
        
        Time saved during construction and ease of work will assist in savings on other partsof work
        
        more expensive to provide and install than an in situ concrete floor
      - Types of concrete:
        
        in-situ concrete floors
        
        hollow precast concrete floors
  - - - Quick and easy to install.
        
        Long life span
        
        Reasonable cost and function.
        
        Availability of supply in addition to having beautiful visual quality
        
        The water penetration limit so that the original characteristics of the roof will not be damaged.
      - The following are several factors that influence the cost of roofs.
        
        The type of roof covering used. There are many materials to choose from.. Each materials has its own advantages and disadvantages, strengths and durability, maintenance and shapes.
        
        The use of pitch roof on high buildings is not economical due to problems in transporting materials, the use of cranes and also wind load.
        
        Plan shape of roof. The more complex the design, the higher is the construction cost. The cost of the rainwater drainage and roof structure will increase.
        
        Life span of building. The life span of the structure and roof covering needs to be in line with the line span of the building. For a long life span, regular replacement of roof and high maintenance works will cause the total building cost to increase.
  - - - The installation of suspended ceiling are more expensive because of the hangers, runners and other installation supports.
      - The type of finishes used for this ceiling is often more expensive than in situ finishes because it applied directly onto the concrete surface
      - However, there is reduction in the cost of wall finishes when the suspended ceiling is below the beams.