What is semi finished? Has smooth walls? Painted? Ceiling? Has plumbing? Level floor? Floor covered with material similar to the regular living space? Has what degree of lighting? Is totally below ground? Has door egress? Has window egress?

But to give my best answer as to what I'd want-- a place for all in the house to sleep in hottest weather. Storage place for my garden tools, though right now they are in a shed/garage in back. Storage for mops and brooms. A work bench or at least table. Open floor space where all kinds of projects could be worked on-- where I did not feel obligated to protect the appearance of the floor. Water connections for doing laundry by hand. Some way to dispose of used water. A sink or portable laundry tub. Sturdy shelves for home canned goods, emergency water jugs, empty canning jars, wine bottles, fermentation jars, very large kitchen pots, small garden pots & punnets, drying racks & electric dryers. Bins for long storing vegetables. Spot for solar oven and its table mount. Clean well-sealed storage for winter blankets, coats, gloves, hats, scarves, and window blankets. Yep, a clothesline, too.

So far, my partly above ground basement stays fairly cool in summer. It would certainly be better if fully underground. Humidity has not been a problem in the 25+ years we've lived here--until this year! I could experiment now -today- with putting some bowls of calcium chloride out to absorb water, the drying it out and re-crystalizing it in the solar oven. Dang-- I'm gonna ask my mate to check with the little hardware store tomorrow to see if they have any calcium chloride!

You can do many things to keep water out of your basement and my husband and I did plenty.
Basements are unusable if they're damp. You have to fix your dampness issues before you can do anything else.

You want passive methods that don't use energy?
Start by routing all the water in your roof gutters AWAY from the foundations. Walk around the house in a heavy rain and see where the water goes. Add gutter extensions, dry creeks filled with gravel, and slope the ground away from the house.

If your basement walls are raw concrete block, paint them with white Drylok. This is a miracle product that keeps moisture from seeping through the concrete into the basement. Do the Drylok AFTER you fix all your outside drainage issues. Unfortunately, Drylok doesn't work on painted concrete block; it chemically adheres to raw concrete. Only use white Drylok (it comes in colors) to maximize light.

Improve your ventilation by opening any windows that you have and inserting screens if they're missing (to keep out critters). You can add windows to a below-grade space, although you'll need a contractor to do this. If you add a window, get the biggest one you can afford to a) let in more light and b) let in more air. You can also make existing basement windows bigger.

Improve the window wells you already have. Clean them, clean the window glass, clean the screen, replace the gravel with white marble chips and keep the marble below the sill level, paint all exposed concrete with white Drylok and paint the window well itself with white paint. The white paint improves lighting and light reflectiveness. Cover each window well with a salvaged storm window, NOT those worthless plastic bubbles Home Depot sells. The bubbles won't last more than a few years and they get cloudy, blocking sunlight. A salvaged storm window can be cleaned and keeps out the rain better.

Make sure you don't have hidden water leakages such as the hole the original contractor punched through the wall surrounding the outflow sewage pipe. That problem (which we discovered when we replaced the front door sidewalk because of its reverse slope) was what caused many of our long-term water issues. That hole in the basement wall let rainwater flow inside the hollow concrete block wall for decades.

Expect to spend plenty of time and money but it can be done. We did!

Good luck!

Teresa from Hershey

I appreciate these tips. Our basement is coated with dri-lock or something like it; the previous owner did it. The walls are mortared limestone, but this dri-lock paint sticks to that, too. There is a place where the stuff has chipped off, but I think that is because the mortar behind it has pulverized. Not sure why that happened, except that it is probably connected with a fire in the basement in 1941. (Um, in 1941, they were using the basement as a kitchen. A lot of people around here did that.) We have such a problem with the living space wall in the room above that spot, too.

The one spot where water started coming in visibly is inaccessible without deconstructing the wood stairs in the corner. On the outside, maybe ten years ago, we paid more than half the price to shore up a concrete walkway between our house and our neighbor's. They were having water come in their basement and could not afford to do the work. Our houses are about 30 inches apart, so water over there would eventually make it to our house. Where the water is coming in is right by where the concrete work was done--just little dams sealing the corner between the walls of the house and the concrete gangway.

Hey, lp, you asked about possible space for boarders or tenants. I did have my brother living down there for a few months. It is quite crude for living space. He probably would have been homeless otherwise, and in that position, a reasonable person is pretty flexible about living conditions. There is a lot of stuff like that that goes on in my neighborhood on the sly, but there are also neighbors who get bent out of shape about having a boarder/tenant/long term visitor without all the formalities of the law, certifications for occupancy, and so forth.

As I've mentioned, I've been slowly fine tuning my retirement options. Looks like I will be building a small living space in my sister's home now. It will have a bedroom, half bathroom, and kitchenette. I'll post some initial pictures soon and go over what I have in mind. Like you I'll be interested in seeing what others here have to say about modifying a basement to get the best use from it.

I'm still going to build a small office/workshop out in her backyard, while turning the rest of the backyard into a micro farm. Just for permit reasons, I can't actually call it a tiny home.

If you are having water issues, then I'd also suggest removing the drywall for several reasons.

First there may be mold or mildew on the wall behind the drywall you don't see, or on the wood studs. Or the back of the drywall, and it just hasn't eaten its way thru enough to show. Are there any soft spots in the wall near where you get leaks? All of that needs to be figured out before you start things like cabinets or shelving.

Once the soundness of the wall has been inspected, you might want to consider insulation, especially on that above ground section. I haven't done any research into what kind of insulation is best yet, but I do want to make it as energy efficient as possible. You can also use that time to add electrical or cable/internet wiring.

My sister's basement is similar to yours, partially in ground, and part above ground. I noticed the other day, at least one crack between the bricks that goes all the way thru (sunlight was shining thru the crack), so a good sealing job inside and outside is on the list.

It has 4 small single pane windows and a walk out door too. I want to have the windows replaced with something that also has a screen, so that in mild temperatures I can get some air. The door is in need of replacing, with the frame too, so that I can use it as a exit. Right now it will close but you really have to do it from the inside. I'd almost like to build a small wet room, or at least an "airlock", so that in hot Summer/cold Winter I could open the outer door, step in, close the outer door, then open the inner one, without letting a blast of cold/hot air into the basement.

You don't mention what kind of ceiling you have. Ours has some sheetrock nailed to the joists, which I plan on taking down. The house has electrical outlets which are ungrounded (two wire), and I'd like to get new wire run and new sockets upstairs which will be easier once the ceiling is exposed.

Unfortunately, we don't have a bathroom down there. The previous owner did build a shower over a floor drain, near where the laundry area is. Its just a couple of 5 foot walls and a short lip, all tiled, with a shower curtain. I'm about to start knocking down the shower walls to expose the pipe. Then I'll get some estimates on having the concrete cracked at the drain, the P trap removed and a flush toilet installed. I was thinking of a composting toilet but at 62, I'm not sure I want to be lugging half full 5 gallon pails outside in cold or hot temps, lol.

We don't have any issues with leaks from the walls luckily but we do occasionally get water backing up from the main floor drain. I need to establish a regular schedule of having the line snaked, instead of waiting to do it when it backs up. I suspect that the pipe to the street may have sections that have slightly collapsed. Roots are definitely an issue.

One unusual thing, there is a room beneath the front porch. Does you home have stairs going up to the front and back doors? We have a small front porch with a floor bed in the front. Under it is a small room which holds an old no loner used fuel oil tank (about 100-150 gallons I'm guessing) and the room has a door to it from the basement. I'm guessing it was for furnace oil. I should have that removed and disposed of, so I have to figure out who does that and get estimates. Once cleaned up and insulated, it might make a nice pantry or root cellar.

I've been thinking about how to keep my basement office / ham radio operations room dry in a grid-down situation, so I investigated the idea of using a chemical dessicant (e.g., calcium chloride), which could be regenerated with solar heat whenever it's abundant. But then I rolled the the usual (refrigerant-based) dehumidifier into the room, turned it on, and closed the door. A day later, I had over a gallon of water in the pan! And so on, day after day, even though there's no visible seepage or source of water in the 1000 cu. ft. room. It IS palpably more dry now, and maybe (as mentioned above) I'm just pulling moisture out of the books, drywall, and paneling, but trying to do that with chemical dessicant would be a real challenge. (I also testify as to the effectiveness of dry-lock paint, and the importance of inspecting what's behind your wall finish. I found an electrical box, for outlets, embedded into the inner-surface of a concrete block, so it wouldn't project into the room.)

I'm thinking that fully-enclosed book-cases, with space for easily-replaced dessicant material, is part of the long-term solution.
That will also require a way to determine when the dessicant is saturated, perhaps some sort of pan-balance to see when it's heavy with water.