Before buying any plot for building, there are many factors to be considered from the engineering point of view. The investment in the plot for making building become worthy only if you consult with the civil engineer before buying a plot. If not, you may have to spend more money on special consideration while building a structure. Like, if the soil of that plot is not strong enough to bear sufficient load of the building in shallow depth then deep or raft foundation or the soil treatment may be necessary.
If you want to shift in a new area then it will be better to consult the structural engineer about the suitability of that area for your dream building project.
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What are the engineering factors to be considered before buying a plot for construction of a building?
Some of the points to be considered before buying a plot in new area from the engineering point of view are as follows:
1. Shape of plot
Square and rectangular plot with length not more than twice the width of the plot, is the best shape of the plot for the construction of a building. The square or rectangular site is considered as best, as the site could be used fully without any wastage of space around it. Other than this shape, there will be a lot of odd-shaped wastage land around and so is not considered worth, the money you spend for the land.
2. Topography
The topography may not influence the location and layout of the building, if the site is flat. But the topography is likely to be a significant design factor on the sloping site ( the orientation of hill-slope and relative wind direction).
3. Direction and orientation
It may seem that there is no effect of direction and orientation of building in structural design and construction procedures. The engineer always has to think about client comfort. The building with sufficient light and ventilation is quite comfortable which is affected by the direction and orientation of the plot. For example, an east-facing hillside will have reduced afternoon and evening sunlight and a south-facing site may receive little or no sun during the winter months. From this, you got an idea which direction and orientation are best.
4. Slope
The slope of the site may have a visual impact of the building on the landscape. Imagine which building look attractive, that in sloppy land or the flat land? The sloppy site makes the need of either excavation of filling which is not so good for foundation because there is a high possibility of differential settlement. And also from the economic point of view, it is advisable to avoid plot or the adjacent land sloppy.
5. Soil type
Soil is the most important parameter to be considered before any construction on it. The total load of the building is distributed in the soil so it becomes important to have good quality soil. The quality of the soil determines the foundation design. The selection of the foundation type is also based on types of soil.Naturally, soil differs from state to state, and if you are living in Ohio for example, it’s important to hire Ohio land surveyors that can conduct a proper survey of the soil.
Building-foundation needs to be stable and strong soil. If not, the foundation of the building could crack, sink, or worst case is, the building may fall. Along with the strength, the soil should have the ability to capture precipitation, so that runoff and erosion does not damage the structure. Have you listened to the name The Leaning Tower of Pisa? The soil underneath seemed stable during the dry season when construction began but, the soil becomes unstable during the wet season and sank under the weight of the building.
Rock is very strong and good for supporting foundation because of their high bearing capacity, stability, and depth. But rock level on the surface becomes a problem of excavation for those who want a basement in their building. Loam (a combination of sand and clay) is great for supporting foundation. Suitability in decreasing order:
Rock
Loam
Sand and gravel
Clay
Silt
Peat
Lower the quality of soil; higher will be the cost of construction of the foundation. And soil treatment for bearing capacity may be necessary if the soil can’t resist the load of the building.
6. Water table
Higher the water table, lower will be the cost to pump it to use. But also the water table affects in the bearing capacity of the soil. So for stability, lower water table is the best. But, this factor largely depends upon the extent of building and water table variation.
7. Distance from the marshy land
The land near the marshy land is not suitable for high buildings. The geological history and land formation of these areas provide different sub-surface conditions that may have caused many difficulties in design and construction. The problems such as excessive settlement, low bearing capacity, high water table, frost heave, and corrosion potential are associated with construction in these areas. For the construction in marshy land or nearby it, detailed soil exploration has to be done and a suitable foundation should be selected. If only sandy soil is found, then friction pile is necessary or if rock strata lie then bearing pile is necessary. It depends upon the load of the building and the soil underneath it.
8. Climate
For the living and the construction of the concrete structures, the temperature 10-25⁰C is the most favorable one. Weather can affect the performance and wear & tear of construction equipment. Lower temperature either completely stop or slow down the process of cement hydration due to lack of heat. And it reduces the bond strength of masonry wall.
The design should take extra care if the climate of that area is too rainy or have a high velocity of wind which will cost higher.
9. Seismic zone
Seismic risk refers to the risk or damage from earthquakes to the building, system, or other entities. It has been defined for most management purposes, as the potential economic, social, and environmental consequences of hazardous events that may occur in a specified period of time.
The design of seismic zone IV / V should have more special care than that of III /IV. Greater the risk of seismic effects, greater will be the design consideration which costs more. It is advisable not to migrate in the seismic zone IV and V if possible but special care can reduce the risk.
After buying a plot, you may build your dream house. The ways to minimize the cost of your building is explained under the topic Reduce building construction cost.
