Can You Expand a Basement?

While I was sitting on the couch of my basement, I was thinking about more neat stuff to add to my man cave. I wanted to put a pool table, a couple of arcade games, and a home music studio. I don’t think all of that equipment would fit because I already have so much stuff laying around.  And so, I thought if it was possible to expand my basement and did a little research.

Yes, it is possible to expand your basement, but the expansion will depend on several factors. There may be local restrictions in your area that prohibits any construction that can be hazardous. There is also the issue of ruining the house foundations. And most of all, your budget. Expanding your basement is not any simple DIY project, and you will need the assistance of a professional before doing any digging.

Technically, a basement is the excavation of your home foundation’s cavity. Expanding beyond the perimeters will likely be dangerous. You will need to hire someone who knows about construction, such as an engineer. If you want to make a new basement underneath your lawn, it would probably be much more straightforward than building one underneath a house.

The house needs support from the soil it is standing on. Digging dirt in the wrong place will result in danger or worse, a section of your home falling apart. The best advice I can give you is to hire a professional. They will sure no what they are doing as long as you give them the blueprints of your house.


There are several factors to consider when you are planning a basement expansion. If you haven’t made up your mind, I listed down numerous aspects to think about. Your man cave is supposed to be considered as a living space where you can spend a lot of time. Expanding the basement is not just for storage; it has to be a safe place where you can breathe and feel safe. Here is a list of factors to consider:


Consider the safety of the operation and how it will affect the overall stature of the house. If not, you can always try other ways for expansion such as excavating your lawn where the house foundations are not affected. Your home is safely situated on the soil underneath, so digging up crawl space for a basement expansion will require extensive knowledge of construction.

If you are an experienced contractor or engineer, you must make sure that the construction is safe.  You need to ensure you and your family’s safety. You can always do the job yourself if you know the right procedure.

Helpful tip: Safety will include getting the right safety equipment for the people involved, including yourself. If you lead the project, consider purchasing the right tools for the job. The right tools will consist of all the safety gear such as hard hats, safety boots, eye protection, and gloves.


The proper training for construction work is another safety factor. If you are not adequately trained to operate any heavy machinery; I suggest you take a course on how to properly use the equipment. Safety is not limited to knowing how to operate heavy machinery. There are specific topics such as hazard identification and learning how to maneuver and troubleshoot heavy equipment. 

Helpful tip: When operating heavy equipment, wear the right gear for the job. You must also visually inspect the equipment before using it. And most of all, only use the machine for its intended purpose. Each piece of machinery is designed for a specific task. The manufacturer’s warning signs on a piece of equipment is not a suggestion. You have to follow the safety guides and instructions strictly.


Now that you have considered the safety of the operation, you can move on to the next part. You should inspect how your house was built and supports the house. Determine the possible course of action. To determine where you want the expansion to take place, you have to find out which zone is safe for excavation.

When a house is built, the basement and the soil surrounding it is the original plan of supporting the building. Any expansions are sometimes not included in the program because some houses are built as it is. There are different types of house foundations. The type of foundation is based on several factors, such as the geographical location, climate, soil, and moisture.

The full basement foundation is one of the most convenient ways of building a house. It gives you extra living space almost the size of the entire house space. The main objective of finishing with a full basement is the extra living space. In this case, your man cave is the best thing you got out of having basement space.


Be aware of your surroundings when you will start the construction. Once you have all the permits to begin construction, strictly follow the parameters to make sure you will not disturb anyone in the neighborhood. If the license says do not work at night, it is because of the loud noise of construction equipment. You should follow that so that you would not get complaints and ultimately not be able to finish the expansion.

Digging a new basement will produce a lot of soil and dirt. Make sure that you dispose of the soil properly and not make a mess on the public roads or your neighbors’ lawn. You should respect the boundaries and scope of the legal permits given to you.


If your basement already has a bathroom or water supply, you don’t need to add any pipes. Installing pipes for a new water supply will take a lot of work. If you are expanding for extra space, do not mind the correctly working pipelines.

If your expansion happens to affect a significant pipeline going to the basement, you should choose a different spot if possible. If it is not possible to change the location, you must hire a professional plumber to rearrange the septic tank system and piping.


 A living space should have proper ventilation. It can be dangerous to add extra space with no room for air. If you have the extra budget, have your extra basement space covered by your home’s centralized air conditioning. If not, you must consider doing all the necessary steps for proper ventilation. 

To properly ventilate a basement, you should add windows for natural ventilation. This method reduces electricity usage. Windows should be strategically placed so that it can be open and closed. Having proper ventilation will eliminate bad odor from mold build-up. The EPA suggests that homeowners properly ventilate their basement so that residents can breathe fresh air while in the basement. Fresh air also inhibits mold and mildew growth.


Some basement can get sunlight if a window or transparent roof is placed where the soil meets the open space. The advantage of getting sunlight is to reduce energy consumption. Having sunlight hit the basement will also make it feel livelier.

You can adequately get sunlight into a basement with the installation of sun tubes. These tubes transport sunlight form the top floor into dark places of a home. The accessible location of sun tubes is mainly in:

  • Closets
  • Bathrooms
  • Kitchens
  • Bathrooms
  • Laundry rooms
  • Basements


The budget is your “make it or break it” factor. Expanding a basement will be a lot of work, which means that it will cost a lot of money. Be prepared to spend a lot of money. Remember to prepare more money than what is estimated by the contractor you hired. By digging up the foundations of a house, you will surely discover unexpected repairs. You might find hidden leaks and more.

Helpful tip: When preparing your budget for the basement expansion, expect the unexpected. Have a little extra money for minor and major repairs your contractor might discover going on under your household.



Here are some advantages of expanding your basement:

  • More space = more fun
  • Discover hidden issues that can be fixed
  • Increase the house value
  • Working on it could be a fun activity if you like that kind of stuff


  • Expensive
  • A lot of work
  • A lot of soil that could mess up your house
  • Might compromise house foundations (have a professional do inspection)


Heavy rains can cause moisture from the soil to the wall foundation. Since you are expanding your basement, this is an excellent opportunity to waterproof your existing walls as well as the newly installed ones. There are tons of materials that could help waterproof such as sealants, waterproof cement, etc.


If you are still experiencing floods despite having a drainage system, expanding your basement could be an opportunity for a drainage upgrade. You can also repair your old sump pump if it is not beyond repair. Sometimes the basin or pump needs to be cleaned or moved to a better location.

To learn more about drainage systems and how to install them, click here.



Basements can be a lot more work and cost a lot more money. Consider making a separate house for your man cave. This option might not cost as much. The only thing is, if your man cave is not in a basement, it does not feel like a man cave anymore. What should you call it?


If it is not possible to extend your basement without messing up your house’s foundation, consider the option of digging a basement under your lawn or backyard. It would require more electrical and plumbing work, but your home will stay secure. The only problem you will have to get through is how to link the new basement to the old one without compromising the safety of your wall foundations.


Adding a subfloor is possible. However, it will cost you a lot more money. You need to find a way to dispose of the soil you dig up. The ground needs to be extracted from the basement and outside the house.  You will also need to figure out a way to properly ventilate the new subfloor. It may be harder to breathe air as you dig down deeper.


It is possible to expand your basement, and there is more than one way to do so. After you have considered all the factors, see If you have significant construction work. If the advantages outweigh the disadvantages, then I guess you are good to go. The important thing is that you and your family are safe and not violating any rules. I hope this article has helped you decide on your basement expansion plans.

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