Reduce building construction cost:
Many people do not want to compromise to reduce building construction costs because they have invested huge amounts of money in their life. Many people connect the heavy construction of building with their prestige, so they want their houses to be unique, attractive, strong, and durable. But they forget that there are also smart ideas that reduce building construction costs without any compromise in strength and durability.
Minimizing the cost of building cost means to cut-off the extra amount that expenses on unproductive field. Unproductive means that field where cost expenses for extra amount of strength, durability, aesthetics view, that is actually not necessary. For example, if a room has capacity for 50 people then it will just a waste of money if it is designed for 100 people. It only increases the cost and it is just an investment in unproductive field.
Yes, it may be right that expensive material will give better result but it is not right for all case. Here I will explains many ways that actually reduce building construction cost and it will neither make you regret not decline your prestige.
If you are an engineer, then you have encounter with questions to reduce building construction cost time and again. So let’s talk about it.
- Selection of plot:
Plot, a place where dream building will be fixed. There are many smart ideas for selection of plot for the construction. Good plots always reduce building construction cost and make the building more attractive and durable. The cost of superstructure depends upon the quality of the soil which support the building. Many people do not think about construction cost and go for cheaper rather than better. Saving amount by buying low quality will always regret people while construction. For more details, click here.
2. Floor plan:
Floor plan determines the internal space distribution and outer look of the building. Any mistake in this steps will not corrective in the future. Thus, take an enough time to think about the plan of the building.
- Floor plan should be simple with rectangular or square shape.
- Make room with multiple functionality.
- Better to avoid basement/garage which will increase extra cost.
- Going for smaller is always smarter.
- Scale down and get rid of stuff space you don’t need.
- Keep some space for open plan living for more daylighting and sociable living.
The effective floor plan optimize the room size and space distribution with no wastage of precious plot. And reduces the construction cost drastically.
3. Construction materials:
Construction material expenses more than 60% of total construction cost. Thus, if we think ideally then we can economize the cost of building. Don’t go for branded product, just assure material are of good quality. You can get lot of local materials with good quality which reduce building construction cost.
Different types of cement are available in the market. It is advisable to use PPC cement which is cheaper but gives same strength as OPC. PPC gives low initial strength but same ultimate strength. But while using PPC, the cost of framework should be analyzed as it takes more time to set. For more details, click here.
For economizing the cost of construction, it would be better to use locally available material or from local supplier. Locally available material costs lower and from local supplier decrease the transportation cost. The coarse aggregate up to 20mm will be better for building construction.
For fine aggregate, use sand of with different fineness for different purpose. For example: for concreting, use coarser sand; for masonry work, use medium sand and for plastering, use finer sand. Use of finer sand become the intelligence thinking because it reduces the cost in finishing/ painting. It is not necessary to apply putty to make surface smooth which reduces the cost. For more details about aggregate, click here.
For the construction of residential house, use appropriate types and amount of steel. Using extra than required may increase strength but it is just waste of money in unproductive field.
Using higher grade cost more that lower grade. But higher the grade, higher will be the strength and less will be the size of structural member. Lesser the size of structural member, lesser will be self-weight of building and cost decreases for sub-structure. Ultimately the use of higher grade will be economical. Here is also an exception, the code has fixed the minimum size of structural member below which we can’t go. This should be analyzed before selection of grade of concrete.
For residential building, don’t use higher grade than M25 for structural member. It is advisable to use M25 only for column and foundation and M20 for other structural members. In case of high rise building, it would be better to use higher grade of concrete as possible.
- Partition material:
Lower the weight of partition wall load, lower will be the size of structural member. The unit weight has greater importance in reduction in the cost of building. Brick has a monopoly in construction of outer and partition wall in residential building. It will be better if we can use material of lower unit weight.
AAC block will be the best option for building of G +4 and more because it only has normal dry density of 550-650 kg/m3 whereas brick has 1800 kg/m3. There are so many other materials with lower density which can be used as partition wall.
- Wooden work
It is better to avoid the use of wood if possible. For door and window, it is better to use aluminum frame with glass panel. But where the security is necessary, steel should also be used along with aluminum.
Note: use of prefabricated material not only reduces building construction cost but also give more strength. It produces almost zero construction wastage and lesser labor.
4. Structural design:
i. Adopt uniform column layout
Layout of the column depends on the plan of the building. The regular shaped buildings will be more economical than irregularly shaped buildings with L- or T-shaped columns. Equal spacing of column make economical in design of reinforcement of slab.
ii. Use standard column size
The same size of column can be achieved by varying the amount of reinforcing steel and the concrete strength within the column. This will minimize the number of variations to meet beam or slab forms.
iii. Use the same depth for beams if possible:
The use of same depth of beam reduces cost in formwork and shoring and eliminate different difficulties. This will provide a uniform ceiling elevation and minimize mechanical service installation difficulties.
iv. Depth of slab:
The depth of slab should be kept as minimum as possible. The reason is to make less use of concrete and to reduce the dead load of the building. The depth of slab can be decreased by providing secondary beams. It is advisable to make the slab design for not more than 150mm.
v. Minimize floor-to-floor height:
The cost associated with mechanical services, stairs, exterior building cladding can be significantly reduced by minimizing the floor-to-floor height. It is better to have clear floor to floor height not more than 3m.
vi. Use concrete with higher grade in columns
The concrete with higher grade reduces the column size or the quantity of reinforcing steel required for the column.
vii. Use repetitive formwork
The cost of formwork may be very high (up to 20%). The cost can be reduced when the framing system is used repetitively (10 or more times) on a structure.
viii. Use steel bar larger size that satisfies the design considerations
Use larger size bars in columns and smaller size bars in slabs. Larger diameter bars reduce the number of bars that must be placed and minimize installation costs.
ix. Eliminate bent bars where possible
Bent bars increase fabrication costs and require greater storage area and sorting time on the job site.
x. Eliminate congestion of steel
Congestion of bars should be avoided, especially at beam-column joints, in order that all reinforcements can be properly placed.
If the building is medium to high rise it is always beneficial to go for performance based design. Due to its complex algorithm and calculation, the engineer’s fee will be increased but it will reduce building construction cost overall.
For motivating me to prepare topic how to reduce building construction cost, special thanks to
Prakash Bhandari, a final year Civil Engineering student
IOE, Pulchowk Engineering Campus