While building a basement is considered one of the first things to do during constructing a house, many people consider building one under an existing house.
This raises concern among homeowners who are planning on such a construction plan, whether they can build a basement under an existing house and what kind of issues it might raise.
We have designed this article to help you identify the things that you should consider before building a basement under an existing house.
We will also discuss how much it will cost to build a basement under an existing house. So let’s read ahead to learn more about it.
Can you build a basement under the existing house?
You can build a basement under an existing house. You will need to dig a basement and provide a support system for it. It will need a strong foundation and insulation system as well. But it will need intricate planning and the involvement of professional and licensed contractors.
Reconstruction and renovation opportunities are some common concerns among homeowners.
It is important to know whether you can add or alter something in your home. So here, we will address a concern among homeowners: whether they can build a basement under their existing house.
Building a basement underneath the home is one of the first steps that is carried out during constructing a new house.
However, if you’re working on an already built establishment and need a basement under it, there’s no need to worry. You can still build a basement under an existing house.
It is possible to build a basement under an existing house. But it demands very thorough planning by professional contractors and experts. It is a very intricate task and there are certain considerations that will need your attention as well.
While you run the process, you will need to build a new foundation underneath the potential basement location. You will also need walls and proper insulation, ventilation, and drainage system for the structure.
The entire process will cost you something between $20,000 to $150,000 so brace yourself for the cost it entails.
Things to consider before building a basement under an existing house:
Here are some of the most important things to consider before building a basement under an existing house.
Consider the cost of the project first. The cost of the project varies according to the location of your house, the charge of the contractors in the area, the property value of the house, and more.
The entire project may cost you something between $20,000 to $150,000. But note that, in a general case, whatever the cost of the project might be, it will most likely be profitable.
Building a basement under your existing house will most likely increase the property value, which will eventually balance the cost of the project.
Leak resistance in the walls:
In order to ensure the well-being of the basement, you will need to ensure that the walls are leak resistant.
Make sure that the walls are built in a manner that they do not allow water to infiltrate. Otherwise, your basement will soon end up with rot or mold.
It is important to ensure that you are waterproofing the basement and installing a reliable drainage system. This will make sure that your basement is free of moisture intrusion. It will keep the walls safe.
In addition, you will need to be very careful with the selection of the bricks. This is important in order to avoid seepage issues. Many people use kachi bricks in their basements, which gives rise to seepage issues.
These bricks will absorb moisture from the air as well as the laying lintel. So you should choose bricks that are moisture-resistant. You can also add ducts on the walls in order to make the walls moisture-resistant.
Experts suggest you install windows on both sides of the basement in order to allow proper ventilation- sunlight and fresh air.
While digging the basement, you will need to ensure that the basement has enough wall space.
Residential basements commonly need 8 inches of poured concrete walls or 8 to 10 inches of CMU walls. You should pay special attention to meeting the building codes.
Height of the walls:
This is one of the most important factors to consider while building a basement. Whether you are building a basement under a new house or an existing one, this consideration will need your undivided attention.
In order to lay a strong floor bed, you will need to dig a deep basement. But what should the height be?
Make sure that the height of the basement is a little more than that of the ground floor. This is to ensure that you have additional space for the windows in the basement.
An ideal depth that is followed in most basements is 20 feet. Basements are typically a little taller in height, compared to the ground level. This is done in order to lift the ground floor.
It is particularly helpful because the windows of the basement will open in the garage, so you will need to make room for them.
Outlets and escape routes:
This is another important factor that will need your thorough consideration. To meet building codes, you will need to consider building escape routes and proper outlets for the basement.
A general requirement, in this case, is to install a window opening that is large enough to allow people to exit from inside the basement to the floor levels.
How much does it cost to build a basement under an existing house?
It costs between $20,000 to $150,000 to build a basement under an existing house.
If you want to expand your house and add a basement under the existing house, it will cost you a significant amount of money.
If you’re building an average basement of 2000 square feet, it might cost you between $60000 to $150000. But be ready to encounter some additional costs as well.
The overall cost may climb as high as $200,000. This charge may vary if your home faces certain challenges or if you need to deal with leaking issues.
However, the charge may vary depending on your location, property value, and the nature of construction that you are opting for.
You will also have to consider the charge of your contractor and subcontractor, which will most likely vary according to their experience and brand value.
But let’s take a look at an average cost structure. Depending on the age of your home, its structure, and some other important factors, you should expect to spend between $30 to $75 per square foot of the basement.
Is building a basement under an existing house a good idea?
This is a common question that we get from homeowners. They often seem to wonder whether building a basement under an existing house would be a good idea.
Let’s take a look at some benefits and negatives that a basement might add to your house or other establishments:
Benefits of adding a basement to a house:
There are actually a handful of benefits of adding a basement to your home. Here are some of the most significant benefits:
Additional storage space:
The most significant benefit of having a basement in your home is the additional storage space that it comes with. Even an incomplete basement can offer this benefit. This works as a major convenience in your everyday life.
Additional bedrooms and bathrooms:
Not only storage space but many people use their basements to build additional bedrooms and bathrooms in the house. This also has a major contribution to the convenience of the house
Added property value:
As soon as you add a basement to your home, it increases the property value of your home. So the cost of the project is neutralized by the increased property value.
Negatives of adding a basement to a house:
Here are some negatives of adding a basement to a house.
Damp and moisture concerns:
When you add a basement to your home, you will need to be aware of the damp and moisture concerns. You will need to invest in leak and moisture-proof walls and construction materials in order to address those concerns.
The construction cost may sometimes seem overwhelming. Admittedly, it costs a significant amount to build a new basement under an existing house. But the cost should be balanced by the improved property value.
You can build a basement under an existing house. But it entails a significant cost and needs your thorough consideration of some essential factors, including moisture resistance, height and strength of the walls, and more. Make sure to involve experienced contractors and experts in the project.
I am an architect with over 5 years of experience in the design and installation of interior and exterior design projects. I have also been a home improvement expert for many years, so I know how to improve your home’s look and feel. I would love to help you build the perfect home for your family!
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