Screwing shut a jalousie window is decidedly quick-and-dirty — the result will appear dilapidated while semi-permanently defeating the function of the windows (possibly jamming window operators by cranking mechanical components). On the other hand, it's easy, cheap, and possibly effective.
How to screw down jalousie windows
We can screw plywood onto the edges to press down the windows that won't close. The metal siding on the edges of the jalousie window is likely aluminum, easily penetrated by general purpose drill bits.
- measuring tape
- general purpose drill bits
Opt for 3/8 inch or 1/4 inch standard spruce plywood on the external face of the window. Thicker plywood will be more conspicuous.
Non-tapered head screws will push down the plywood better than tapered or bulge-head screws, but ultimately any kind of exterior wood screws will work. I circled those I think would work best:
Use four, narrow pieces of plywood arranged in a frame-like rectangle measured to the width and height dimensions of the target window.
You can prepare holes in the window and the plywood frame using a strip of paper as a drilling template. If the window is not square (width is not the same as height), you'll need a template for the sides and a separate template for the top and bottom.
Draw lines at the top and bottom of the window, then choose where the screw holes will go by drawing the intended hole marks on the template. Align the top/bottom of your template with your plywood frame so that the holes on the plywood will line-up with the window's holes, then drill the same hole spacings on the plywood.
Consider fixing jalousie windows
If you are repairing your own home, semi-permanently disabling the windows (making them even more difficult to replace) could negatively affect your resell value. Window mechanisms also deserve better!
This is why, if you have the time and the tools (and skills), you might consider fixing or restoring the windows so they close properly. The fix might be as easy as putting a little WD40 in the window operator mechanism or it might require a more careful approach.
Cannedhamtrailers.com shows how to restore jalousie windows in this video: Restoring A Jalousie Window
Also, a FamilyHandyman.com article suggests several diagnostic steps to identify the problem precisely: How to Repair Jalousie Windows