Joists and beams are both part of the flooring system above your basement, with the beams spanning the length of your home and getting support from vertical posts underneath, and joists usually spanning half the width of your home with no support posts underneath. The floor joists provide even support to the subflooring and flooring above, and they distribute that load to the beams. The beams then distribute that load down through the support posts to the foundation.

Some older homes have toilets in the basement to combat sewage backups. This type of toilet, also known as a Pittsburgh potty, acted as a safety valve over the incoming sewer line. If a line backed up, it would back up into the toilet because it was the lowest fixture in the home, keeping it out of sight and away from the finished areas of the house.

Basement toilets were also used by workers with messy jobs, like those who worked in coal mines or steel mills. This way, they could clean up and avoid tracking dirt through their home.

If you don’t have a crawl space but have a partial basement you want to make deeper, you can expect to spend a little less—between $40,000 and $90,000 on average. However, if you’re not adding new finished square footage, you won’t see much in the way of ROI.

Building up by adding square footage to the top of your home is often less expensive than adding a basement, but it depends on the specifics of your house, your property, and supply costs. Because building a basement requires excavation, it can be a more expensive option than building up.