Every single house in Nepal is built on ground. The ground varies between each plot and therefore conducting a soil test will provide you with the information about your ground. It will let you know what type of soil you’re building on, how much load can be carried, if there are any issues with water or weak areas. This will help you design your foundations, how much the building will settle, how stable it will be and how much it will cost to build.
As the ground can vary between plots on the same street, you cannot rely on your neighbours report. A soil test will give you specific information about your land and building. This guide will help you understand what a soil test involves, when to conduct one, what information will be provided within the report and how this can help you decide on your foundations.
What Is A Soil Test?
A soil test is carried out on your plot to gain a good understanding of how the ground will behave under the weight of a building. It will basically give you information about what type of soil you have, how strong it is and how it will react to water.
It will give the structural engineer accurate information to help him design your foundations. Without this information he will have to assume the size and depth of your foundations.
A typical soil test will involve 3 stages. Firstly there will be some ground testing on site, this could include boreholes or trial pits. Soil samples will also be taken from the ground at various depths. This will be either disturbed or undisturbed samples. Finally the soil samples will be tested in a lab. The quantity of samples will depend on the site, building size and number of floors. The Department of Mines and Geology publish information about engineering geological investigations and geotechnical lab services in Nepal.
Why Should I Consider a Soil Test?
Your building can only be as reliable as the ground it is built on. A proper soil test will give you:
Understand Your Soil
A soil test will give you an understanding of what type of soil you have, what layers are present within the ground and general characteristics. Different soils will behave differently. Often there will be more than one soil type on your plot.
Bearing Capacity
This will give you an understanding of whether the soil can safely support the loads from your proposed building. This is one of the most important parts of your report. A soil bearing capacity test in Nepal will let you know what size your foundations will be.
Settlement
All buildings will settle however if there is a differential settlement this can cause cracks in your walls, floor and beams. A soil test will help you understand how much of a risk this is.
Foundation Design
Your engineer will use the soil test results to decide what type of foundation you will need, how deep and how large. If you want to understand your options take a look at our article about the different types of house foundations used in Nepal.
Groundwater and Other Issues
Issues such as high groundwater, weak/loose soil and filled ground can all be site specific. By finding these out early you can plan accordingly.
Avoid Issues During Construction
Fixing issues during construction can be very costly. By carrying out a soil test early you can reduce the chances of having to redesign your foundations.
What Will Be Tested?
Typically a soil investigation report will provide you with:
- Type of Soil
- Bearing Capacity
- Density & Compaction
- Moisture Content
- Groundwater
- Settlement & Stability
This will give you a clear understanding of how your ground will behave.
What Type Of Test Will Be Carried Out?
There isn’t one test that can be carried out on every site. The right combination of tests will depend on the type of soil, plot and building size.
There may be some ground investigation on site; this could include trial pits or boreholes. Tests may also be carried out on-site, such as standard penetration tests to give you an indication of how strong the soil is at various depths. Soil samples will also be taken to be looked at in the lab. In the lab they may carry out grain size analysis, moisture content, density, plasticity, and shear strength tests.
Qualified professionals should carry out the right tests. Usually a geotechnical or structural engineer, in conjunction with a testing lab. If you don’t have guidance you may miss out on some data.
When Should A Soil Test Be Carried Out?
Ideally you should carry out one before designing your foundations. However, there are certain situations that you should consider:
- Before designing your foundations.
- When purchasing land with unknown ground conditions. See our notes on how to assess your plot before buying for other tests you may want to carry out.
- On filled, disturbed, sloped or difficult ground.
- If there are concerns about groundwater or settlement.
- If required by any regulations.
How Will A Soil Test Be Carried Out?
The soil test will usually follow these 4 stages:
Site Investigation
An engineer will visit your plot and take a look around. They will note down any information about the terrain, drainage and nearby structures. They will also decide where they want to test.
Soil Sample Collection
Samples will be collected from trial pits or boreholes at the desired depths. Great care will be taken to ensure the samples are representative.
Testing
Tests will be carried out on-site and in lab to give you the right information about the soil. This may include strength, density, moisture, and soil type.
Analysis & Reporting
The results will be analyzed and a report produced.
What Information Will Be Included?
A soil test report should be clear for your engineer to use. Typically it will include:
- Site & Investigation Details
- Soil Profile
- Field & Lab Results
- Bearing Capacity
- Groundwater (if investigated)
- Conclusions & Foundation Recommendations
If the report doesn’t give you any detail just a number ask the testing company for more information.
How Will The Results Influence Your Foundations?
Your foundations must support the weight of your building and transfer this safely into the ground. Your engineer will look at the anticipated loads and compare them to what the soil can support. If the soil is strong and the loads are low then a simple foundation may be suitable. However, if the soil is weak, varying or wet then you may need to adapt your design. This could include larger foundations, deeper foundations or changing the type of foundation.
The main things to consider are bearing capacity and settlement. Bearing capacity will tell you whether the soil can support the load, and settlement will tell you how much the ground will compress. Both of these should be acceptable.
Your foundation should be decided by qualified professionals. As a homeowner you shouldn’t choose a foundation based on the number given. The ground is just one element to a safe structure. Find out how the foundation, frame and materials work together in our guide to earthquake resistant house construction in Nepal.
What Can Happen If I Don’t Carry Out A Soil Test?
By not carrying out a soil test you are leaving yourself to risk. Common issues include:
- Incorrect assumptions about the soil.
- Settlement or differential settlement.
- Changing your foundation design.
- Delays to construction.
- Unplanned costs.
- Increased uncertainty throughout construction.
The cost of a soil investigation is minimal when compared to the cost of fixing foundation issues.
What Sites May Require Extra Investigation?
Some sites may require more investigation. This doesn’t mean the plot isn’t suitable but your engineer will need more information to design your foundations.
Fill Or Disturbed Ground
Fill can be loose and not uniform. Quality can vary.
Soft or Loose Ground
Soft clay or loose sand can compress more under load and may require specialist foundation design.
Near Rivers or Groundwater
Having a high water table can reduce the strength of the soil. This can make excavation and waterproofing more difficult, especially for deeper structures like basements.
Sloped or Difficult Ground
Slopes can cause stability, drainage and retaining issues.
Visible Settlement
Cracks in nearby walls, uneven ground or tilted structures can indicate that your ground should be investigated.
Larger/heavier residential buildings
The more floors you have the higher the loads will be. Therefore, the soil information becomes more important.
Visual Site Investigation
A visual site investigation can give you information about the surface. This can include slope, drainage, vegetation, nearby buildings and visible cracks.
However it will not provide you with any underground information. You won’t know what layers of soil you have, how dense, moist, groundwater or bearing capacity the soil has. Only a soil test can give you this information. A visual investigation can help you decide where to carry out your tests but it cannot replace a soil test.
Soil Investigations In Nepal
In Nepal a soil investigation is a normal part of responsible residential building. Much of the country is seismically active and therefore there is a wide variety of ground conditions. Some areas of the Kathmandu valley have soft deposits, whilst others will have slopes on hills and river terraces.
The Nepal National Building Code provides information about what is expected for a safe design. This includes the seismic design code (NBC 105) and site considerations code. You can find these on the Department of Urban Development and Building Construction website. The requirements will depend on the size, type and location of your house. Your municipality may also require certain documents to be provided. Speak to your engineer to confirm what the current edition of the codes are and what the local rules are. Our article on the naksa pass process in Nepal explains how permits are approved.
How To Choose A Soil Testing Company In Nepal
Look for:
- Qualified and experienced professionals.
- Right tests to be carried out.
- Clear and detailed report.
- Appropriate field and lab testing.
- Transparent information about what is included and the price.
- Working with structural/geotechnical engineers.
- Working with a builder who will include the testing in their plan and can explain the report to you in simple terms.
Planning To Build A House In Nepal?
Investigate the ground before designing your foundations. Share the soil report with your structural engineer. Ensure that your design and construction team are all working from the same information.
At Jadan Construction we can help homeowners plan and build their homes. Our process works step by step to ensure the engineering is correct. You can find out how we work on our RCC & Steel Structure Construction Service page.
Contact the Jadan Construction team to get started.
Conclusion
Understanding your soil is one of the most valuable things you can do when building a house. A soil test will tell you how much load your ground can support, any risks and what your foundation will need to do. This will directly influence your foundation design to ensure it’s safe. It will also help avoid any delays and unplanned costs.
Ensure that you seek the right professional advice and conduct a soil test. Let the results influence your design. Contact the Jadan Construction team for help with planning your project.
FAQs
Do I need to carry out a soil test for my house in Nepal?
It is highly recommended that you carry out a soil test for any house. Often engineers and local authorities will expect you to. Nepal has varied ground conditions and is prone to earthquakes. Without knowing the soil conditions you are adding unnecessary risk to your foundation design. Speak to your engineer and municipality to confirm exactly what is required.
What will a soil test tell me about my house?
It will tell you what type of soil you have, what layers are present, bearing capacity, density, moisture and groundwater. All of this will help you design your foundations.
When should I conduct a soil test?
Before designing your foundations. Ideally before finalizing your building design. If you are still deciding whether to purchase your plot then carrying out one before can help you avoid any surprises.
What is bearing capacity?
Bearing capacity is how much load per unit of area the ground can safely support. This is typically given in kN per square meter and used by engineers to calculate the size of your foundations.
How will a soil test influence my foundations?
It will tell your engineer how strong and stable the soil is. This will influence what type, depth and size of foundation you will have. If the soil is weak or varying, you may need larger or deeper foundations or change the type.
Can I build without a soil test?
Some people do however you will be working off assumptions for your foundation. This increases the risk of settlement, cracking, redesign, and increased cost. A soil test is a small investment.