Alcove Greenhouse

Story

We have a number of plants that are tropical, but we do not live in a tropical climate. They would not survive a freeze and it sometimes freezes here in the winter. Our solution has been an annual rite of moving plants in our garage. However, garage floor space is at a premium, and with an increasing collection of tropical plants, I decided we needed a better solution.

After

Before

We have a small alcove area off our master bedroom that almost has 4 enclosing walls, but no roof. By adding a roof and closing off the missing wall part, I could create something akin to a greenhouse. This is not really a greenhouse as it has no temperature control and many other missing elements, but it effectively functions like one for our cooler months.

I had been thinking about this for a few tears, but having recently completed a project to improve the floor of the alcove area, I was motivated to turn this into reality. See the Alcove Pavers Page for more about that project.

Creating Door and Roof Frames

All we needed to enclose the area were two panels: one for the doorway and one for the ceiling/roof. These would be painted mahogany frames with clear, polycarbonate panels. I used mahogany because it is a hardwood, has better pest resistance and I had a bunch of this lying around the shop.

Assembled frames.

Assembling roof panel.

Painting frames in progress.

Installing embedded nuts in frame.

Embedded nuts (closeup).

Adding handle to panel.

Preparing Polycarbonate Panels

I did a lot of research about how to make a greenhouse, which is how I know that what I was creating would not actually be a greenhouse (though I still call it that). The most relevant parts were about the clear polycarbonate panels. Polycarbonate is far stronger that I previous knew, so my concerns about hail doing damage was diminished. Further, for insulation purposes, you want the air layer that double panel polycarbonate provides. Lastly, because there is an air gap in the panels, you have top be concerned about fogging and insects.

The solution to keep bugs and water out of it is two fold:

Aluminum Tape. You put this on the ends of the panel that are highest. This provides a water tight seal that prevents rain from getting in.
Clothe Tape. You put this on the lower edges for the panel edges. This prevents inspects from getting in but allows the panel to breathe so you do not trap in moisture as the humidity level changes.

Aluminum tape on polycarbonate panel.

Cloth tape on polycarbonate panel.

Cloth tape (closeup).

Assembling and Test Fitting

Assembling polycarbonate panels.

Roof panel fully assembled.

Fitting door before finishing.

Test fitting of door.

Fitting roof panel before finishing.

Roof panel support brackets.

Insulation

The keep to controlling the temperature on the very coldest days I needed to seal all then edges. Simple foam weather stripping worked in most places, but around the door was problematic. The sides of the door are very uneven stone blocks. Getting a seal against those required something flexible, yet strong. I found a stiff foam like material that was easy to cut, so used this after contouring it to fit the wall profile.