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3F -ECONOMICS OF BUILDING DESIGN, economical factors, MATERIALS - Coggle…
3F -ECONOMICS OF BUILDING DESIGN
BUILDING MORPHOLOGY
BUILDING STOREY HEIGHT
The higher the storey height, the higher the building cost (with the same GFA)
The storey/building heights are subjected to building approval by relevant parties
BUILDING TOTAL HEIGHT
If the total height of building increase, construction cost for high structure building is more than a low building that offers same GFA
Maintenance cost increase because the higher building are more difficult to do work and need special equipment
higher the building goes, more scaffolding requirement. when this happens, financial needs will increase as well.
BUILDING SIZE
The bigger the size of building, the decrease of unit cost.
the greater the floor area of a building, the lower cost per square metre .
The higher wall to floor ratio, the higher the building. (complicated design)
BUILDING PLAN SHAPE
The higher the ratio,the more complicated the floor design.
The higher the ratio,the higher the cost of building.This is because,there is an increase in measurement works,foundation works,external walls,wall finishes etc.
Irregular shapes will also affect cost increases
The budget of a building will differ with just a change in its plan shape even if other factors remain unchanged
The ratio off wall to GFA is one of the ways that can be used to determine which building is the most economical
If the building group together, cost of wall decreases
If the narrow fronted building, the lower cost needed
If the broad fronted building, the higher cost needed
CIRCULATION AREA
The higher percent of circulation area, the decrease of building income.
The rent obtained greatly depends on the net or usable area
SITE CONSIDERATION
SITE PLOT RATIO
Site plot ratio determines a total height of building
If the site is small, the building need more floors upwards or below ground level.
The higher PE ratio, the more efficient the building plan. (it will give a lots of income returns).
SITE TOPO & GEO : :
The topography of the land has impact on foundation design, particularly on sites with steep slopes
A special foundation is needed if the sites have high water table and causes problem with the foundation
Each soil has a different load bearing capacity.Good soils are those that have a high load bearing capacity
For soft soils, the use of pilling may be required
SITE PLAN SHAPE
Plan shape effect the overall cost of the project
If the building standing alone,the cost will increased
SITE LOCATION
If the site have many high-rise building, there's high possibilities that the practical and economical aspects of the building to be ignored.
SITE SIZE
If buying adjacent sites it will make development more economical
If the size of the land limited, the size of the building will be limited too
COST IMPLICATION ON CONSTRUCTION METHOD & BUILDING ELEMENT
SUBSTRUCTURE
soil influence time and cost for excavation
LOAD BEARING CAPACITY OF THE SOIL
Soil that has low load bearing capacity need larger foundation than soil that has high bearing capacity
Foundation cost for soil that has high load bearing capacity are lower than soil that has low load bearing capacity
TYPE OF SOIL
Different type of soil influenced the materials that are used in foundations
TYPE OF CONSTRUCTION
Suitable type of foundation depending on the building
factors such as dead load, live load and wind load considered during determining the appropriate type of foundation
TOPOGRAPHY OF LAND
Sloping site will cause usage of step foundations and additional excavation
Number of bricks used for works below ground floor level will be more compared to a flat site
Shape and orientation of building due to sloping site will influence the cost
Adjustment of the foundation position's level in order to take into account the cost of cut and fill operations.
FRAME
MAINTENANCE
Every framework has its own maintenance based on the damage by the impacts of environment and it will cause a big amount for replacement cost.
Manufacturing overheads are of two further types:
1.Variable overhead
Variable overhead is a cost that is constant when calculated per unit but becomes variable when added to the volume of output.
All costs include costs such as repairs and maintenance, indirect labour, etc.
These overhead costs can vary according to current economic conditions. Either you can increase the price or lower the price.
fixed overhead
Fixed costs tend to decrease per unit with the increase in the production output. This category includes costs like rent, depreciation and salary of the managers, etc.
The overheads costs that are constant when already total but variable in nature when calculated per unit are known as fixed overheads.
MULTI-STOREY BUILDINGS
The floor loading will affect the optimum beam spacing.
The higher the floor span, the higher the thickness of floor in building.
.A rectangular shape is more economical than a square
Materials
Steel and concrete are commonly used to construct frames. Timber, aluminium, and a variety of other materials can be employed. When compared to in situ concrete frame and floor, a steel frame with precast concrete floor and slabs will be faster to construct.
Factors that affect cost
Materials used
Time will effect cost due to erection length of time that needs to be truly precise and carefully install
TYPES OF FRAME
Steel frame
Cost may not be effected as no formwork to be used due to its flexible for a grid system and easy to install
Faster construct but the cost is expensive. And it is non renewable material.
Precast concrete frame
Effected the cost due to its installation on site whether it is influenced by the size of plant to be used to hoist, a special transportation needed if site is far from factory, and needs a good component jointing system during installation
In situ concrete frame
Because the columns do not support beams, buildings with short spans are more cost-effective and appropriate for construction with a concrete frame. Because of the rise in the size of structures, the weight of concrete structures is larger than the load that it will carry for buildings with large spans.
SMALL BUILDING(SINGLE STOREY)
Have a roof structure that is supported by a framework of columns and beams.
ROOFS
ROOF COVERINGS
Materials
clay
slate
concrete
metal
combination of several synthetic materials
Factors to be Taken When Choosing The Materials to be Used
reasonable cost and function
low cost, easy maintenance and repair
quick and easy to install
long life span
availability of supply
the water penetration limit
Factors that Influence the Cost of Roof
Plan shape
complex design consume higher construction cost
cost of rainwater drainage will increase for complex design
pitch roof on high building is not economical
it is not economical because to transport the materials, the use of crane and to make the roof support the wind load will make the cost become higher
type of roof covering used
There are a variety of materials from which to pick. Each material has its own set of benefits and drawbacks, as well as strengths and durability, maintenance requirements, and various forms.
life span of the building
for a long life span, will cause the total building cost increase
UPPER FLOOR
If the span is small, the size of the joist is also small
The larger floor span, will increase the total cost to provide more strength
Hollow precast concrete more expensive than an in situ concrete floor
Precast concrete can be installed in any weather rather than an in situ concrete
Too small shape and areas not suitable for precast unit
For the size of the component structure and the thickness of the load bearing wall, it depends on the weight of the floor
Types of used affects the cost. - If use waffle floor can decrease the cost of beam.
FINISHES
Various types available for floors, walls and ceilings
Type
Floor
Laminate
Ceramic/Porcelain
Carpet
Stone
Vinyl
Cork
Wall
Tile Cladding
Pebbles Finish
Flakes Finish
Coral Finish
Sand Textured Finish
Stained Glass Finish
Ceiling
Suspended Ceilings
Shed Ceilings
Tray Ceilings
Flat Ceilings
Cathedral or Vaulted Ceilings
Cove Ceilings
High Ceilings
The choice of finishes depends on the class and type of building
Standard internal wall finishes can be valued but the area will vary, total window and door openings will have an effect on total wall finishes
Suspended ceiling are more expensive but less costly if its below the beams
There is reduction in the cost of wall finishes when the suspended ceiling is below the beams.
The area on the sides beam usually not treated
INTERNAL WALLS AND PARTITIONS
The choice of a demountable internal dry wall is influenced by how demountable is the said wall, fire resistance strength,acoustic charecteristic, shape, cost,weight and integration of service facilities
ADVANTAGE
simpler design and details due to reduction in load
reduction in cost for preliminary works due to reduction in cost of building works and savings in contract period
reduction and structure size due to reduction in dead load
The cost will be changed if the room and shape of buildings are different and indirectly, causing internal walls and partitions to be considered as well
WINDOW
Material
timber
steel
aluminium
plastic
stainless steel
Window cost consist of
constructing the window
ironmongeries
glass
decoration
work around window opening
FORMULA
Gross Floor Area (m2)
Length of building x Width of building
Wall Area (m2)
Perimeter of building x Height of wall
Ratio for Wall to Gross Floor Area
Wall Area ÷ Gross Floor Area
Party/External Wall per Unit
Total Length of Party/External Wall ÷ Number of Unit
% of Circulation Area
(Circulation Area/Gross Floor Area) x 100
economical factors
Factors influenced window cost
Material used
method of manufacturing
size of the window
safety requirement. If window comply with safety requirements, cost will increase.
the type of hinges,slides and pivots used. If sliding window use, the cost will increase
type of glass and iron mongeries
The performance in terms of weatherproofing and manufacturing quality
Cost will be lower if a standard window
MATERIALS