We have a four-door house: there's a front door and a back door, a side door along the driveway that opens into the basement stairs, and a concrete-and-steel Bilco (cellar) door on the back of the house.
This last door was installed by the previous owner, a plumber, who wanted to navigate large and heavy objects into the basement. It has been very useful the one or two times we had to store a piece of furniture, but beyond that it just sits there, interfering with our backyard patio plans.
So what do you do with a concrete stairwell leading into your basement from the outside? Well, if it faces south, how about turning it into a greenhouse?
I was mulling this over for a long time before doing it, because now we have a baby, and having a baby means that you put off all home improvement projects until never. Watch for House Hacking part II, sometime in the next 10 years. But the basic idea was to take off the steel Bilco door, put up some kind of clear plastic, and use the stairwell to grow plants. It had to be waterproof, safe (no chance of a hooligan falling onto it and dropping into the stairwell below,) and capable of egress in an emergency.
After a lot of planning, I decided on a tent-shaped wood frame that would hold standard 3x6 acrylic panels you can buy at the Home Improvement Box Store. The frame is made out of strips of hardwood, and the bottom rails are a bit wider than the other wood so as to provide a lip that holds the plastic in place. I bought pieces of "L" aluminum to hold the plastic at the bottom, acting as gutters to throw the water forward into the yard.
After a lot of calculation, all of the actual sawing, gluing, screwing and water sealing only took only a couple hours. It actually took more time to buy the acrylic sheets and navigate them into a car without snapping them.
The stairwell and thus the wood frame is only 64" long, and so I bent the 72" plastic sheets around the edges using a strip heater. A strip heater is a standard tool for manipulating thermoplastic. It's just a plug-in heating element in the form of a flexible strip; you lay it down, lay the plastic over it, wait half an hour, and try to bend it along the heated part. Great for making shelves, business card holders, and maybe one or two other things you might think of. I shudder to think that I was originally going to try this with a heat gun, which would not have ended well.
Bending the plastic over the edge of the frame is perfect for making a simple but waterproof greenhouse roof. All I needed after that was a seam of plastic and/or tape along the top, where the two sheets meet. It also solves the problem of the plastic sliding forward off the frame, since the whole thing is tilted forward. The bent ends grip the frame, and also mesh into each other pretty nicely.
Finally, bending plastic is much nicer than cutting it: it's less work, less risk of ruining the plastic, produces cleaner results with no waste, and it does not cut your hands.
For the ends of this little prism, I used a scrap sheet of acrylic at the front, and a sheet of stiff foamboard insulation with a reflective surface for the back. I wrapped this in plastic to keep the water out, and used a couple staples to keep the front acrylic in place, like building a picture frame.
Removing the old door was a simple act of pulling out the cotter pins on the door frame; the greenhouse just sits on top, and the plastic just sits on top of that. Nothing is locking this thing in place, and in an emergency you could just push the whole thing out of the way. There is a bolted door at the bottom of the stairwell, so security is not a vital concern; however, it should be a snap to secure the frame to the old hinges, and latch the plastic to the frame from the inside.
Here's the view from the basement:
So basically the end result is somewhere between a walk-in greenhouse and a covered garden bed. You can walk into it, but it's no more work than a covered bed.
As an added plus, this should bring continual light into the basement, if we can somehow install a glass door at the bottom. That's important because of building codes: in NY State, if you want to put habitable space in your basement, you need windows equivalent to 8% of your finished square footage.
What next? Aside from filling it with plants, we have to figure out heating and ventilation, and probably whitewash the concrete. Given that the plants will lie on the steps, maybe we can put in some kind of shelves to increase the capacity, and of course hooks for hanging baskets.
Finally, this brings us that much closer to working on the rest of the basement, if we don't end up spending the rest of the summer gardening.