Five Cheaper Ways to Add Square Footage to Your House

Finishing an existing unfinished space

Completing areas in your home that are currently not fully utilized, such as basements or garages. These spaces are not considered livable due to their unfinished state, but finishing them can increase both the value and usable area of your home.
For instance, garages are often the most cost-effective spaces to finish since they are typically connected to the main level of the house and already equipped with basic amenities like electricity. The average cost for converting a garage into usable living space is approximately $15,000. However, this cost can vary based on factors such as the need for plumbing (e.g., for a bathroom), the size of the garage, or if you're only converting a portion of a multi-car garage while leaving space for parking.
While converting a garage can provide extra square footage, it's important to consider that you will lose covered parking. Despite this drawback, converting a garage can be a budget-friendly way to gain more usable living space within your existing home.
Unfinished attics and basements are also obvious targets for finishing, with the cost to finish a basement averaging about $55000 the cost of finishing an attic averaging $ 45000

Enclosing an outdoor space
involves transforming existing outdoor areas, like patios or porches, into indoor living spaces, effectively adding square footage to your home. This process can be quite comprehensive, including tasks such as laying new foundations, incorporating plumbing and wiring, adding walls, windows, and doors to connect the new space with the existing home.
The cost of enclosing an outdoor space depends on the scale of the project. Converting a patio into an enclosed space might range from $35000 for smaller projects to several hundred thousand dollars for larger undertakings. Similarly, converting a porch into a four-season room could cost between $40,000 to $120,000 on average.
For a more budget-friendly approach, you could consider creating a sunroom or a three-season room. These spaces are less insulated and lack heating, making them less expensive to build. Screening in a patio can cost as little as $700, while a three-season porch might be obtained for less than $20,000. While these spaces may not qualify as official bedrooms and are less suitable for colder weather, they still contribute value and usable area to your home.
For those who are skilled in DIY projects, there are cheaper options in the form of DIY kits. These kits, which don't include labor costs, can complete the job for as low as $2,000. They usually require just a few days to construct, making them an attractive option for cost-conscious homeowners with the necessary skills

Create bump outs or dormers

A "bump-out" is a small addition to a room that extends outward, usually around two feet deep. It's supported by the existing foundation, so it doesn't need its own foundation. This can add a few dozen square feet to your home, and the cost varies from $8,000 to $45,000 depending on size and complexity.
An "attic dormer" involves adding dormer windows to your attic, which increases ceiling height and brings in natural light, making the space usable. Although it doesn't significantly increase square footage, it transforms the attic into a bright room. The cost for adding attic dormers is generally less than $27,000.

Create a loft

if your house has a room with high ceilings, you can create extra usable space by constructing a loft area. This loft can be a do-it-yourself project to save on costs. It provides the opportunity for an office or additional storage without taking away from existing areas. The cost of building a loft area within a room varies based on your plans – whether it's just a simple platform for a bed or a fully-equipped office. The expense can range from a few thousand dollars to tens of thousands, depending on the complexity and scope of the project.

Add a prefab shed/ADU
if you have a backyard, you might think about adding a small house (known as a tiny house or Accessory Dwelling Unit) or a prefabricated shed for extra living space. These tiny homes can be affordable if you build them yourself, starting from around $8000. You can equip them with power, plumbing, climate control, and nice interior finishes to make them suitable for living. However, it's important to check with your local government about permits and regulations before making a purchase.