Cheap and Fast Method To Screen In Celosia Windows

[ Note: Bible fans, please excuse this brief departure from Bible topics as I dedicate a blog post to help my fellow expats in Costa Rica to sleep better, mosquito-free. ]

Materials Needed

  • Screening (from EPA, either nylon or metal)

  • Styrofoam molding (from EPA, if you opt for nylon screen)

  • Scissors (I use hefty Cutco scissors, the famed cut-through-a-penny kind)

  • Measuring tape (optional, you can just lay the screen against the window and cut over it)


There’s nothing worse than turning off the light, jumping into your comfy bed with the anticipation of much needed sleep and minutes later realizing…you are not alone. You hear the buzzing sound of a mosquito on the prowl somewhere near your bed. Arghh! You think, “Somebody forgot to close a window.” Yes, a window without proper screening.

Why do you live in a house that has windows without screens? Because you decided to move to Costa Rica where they are viewed as an unnecessary expense (I still don’t understand why). This leaves you with the choice of remembering to close the windows at sunset and thereby cutting off the fresh cool air while you sleep, or staying cool and hoping your mosquito repellents (either on your skin or plugged into the outlet) do the job. That is, unless you get fed up enough like I did and find some way to retrofit some screening on your presumably non-screen-friendly windows.

The windows I refer to are the standard ventana celosía or shutter windows like this that you see at least one of in most if not all homes in Costa Rica:

Notice in the picture the red lines highlighting gullies on either side of the window. These gullies are the key to getting screens in place over your windows—and they allow it to be done without nails, tape, or glue. Plus you will still be able to open and close your windows.

Once I noticed those gullies, I headed over to EPA (Costa Rica’s Home Depot) to see what they had for screening and for something to jam the screening into the gullies. It turns out they have both nylon and metal screening in rolls that are 91 cm wide. I don’t have the price offhand, but the nylon was cheaper, perhaps a couple hundred colones per meter and the metal about double that. I found that either worked well but with different advantages and disadvantages:

Nylon Screening from EPA (on a tile floor)

Nylon Screening: cheaper, easier to work with, requires anchoring material/stuffing to stay in the gullies

Metal Screening: less cheap, stiffer and harder to work with but edges roll up and stuff into the gully and stay there without any need for “stuffing”


Styrofoam molding from EPA

For jamming the nylon screening into the gullies, I found styrofoam trim concrete molding worked the best:

This styrofoam molding was found in the same isle as the screening I bought at EPA. It is also dirt cheap, just a couple hundred colones for one piece. One piece did many windows for me (and I never quite used the entire piece up).

Before you go to EPA, measure your windows to determine how many meters of 91 cm screening you need to cover them. You should add in several inches to your width of the window so you have extra material to stuff it into the gullies on either side (and to “bubble” out from the window so the window can open and close without ripping the screen). Sorry, I don’t have exact figures from what I did. My advice is to buy more screening than you think you need so you don’t have to go back to EPA. It’s so cheap, even if you bought double of what you thought you needed, you would not spend a lot.


When you are ready with all your screening material and your scissors to cut it (and the styrofoam if needed), here are the steps.

What you are aiming for is to cover the window from top to bottom with the screen bubbled out enough to allow the clearance of the slats when opened, as in this picture:

Finished window with nylon & styrofoam
  1. If you are using nylon, cut off several pieces of the styrofoam about one inch thick each. (They will look like little solid P’s if you were to lay them flat.)
  2. Open you celosia window full. This will help you to know how high to bubble the screen high over the window so that you can open and close it.
  3. Lay your screen against your window near the top and begin to roll its left top edge inward. If you are using metal, you need to roll the edge over a few times so it bunches up and thickens enough to stuff into the gully.

    For nylon you only need to curl it inward halfway in a semi-circle. This leaves an opening to then insert a styrofoam P (bottom of P first) into the gully. This P will naturally bubble the flimsy nylon out giving the needed clearance.

  4. Top: Once you have the top left corner in place, you can try to get the top secured. Many celosias have a fixed pane at the top that does not move. I have been able to loosen its metal frame and slide it down leaving a gap. I can then stuff the top of the screen into that gap and slide the glass back up into place (again, be careful to loosen the metal frame before attempting this so the glass does not break). If you secure the screen at the top this way, the rest of the installation will go much easier.
  5. Left side: Continue down the left side stuffing and inserting styrofoam as needed to keep the bubble clearance. I typically need one P at each corner and then two or three in the middle.
  6. Right side: Do the same for the right side.
  7. Bottom: For the bottom, I just curl the screen inward like I did for the sides and let it hang there. The thickness from the curling naturally closes any gap below the window that mosquitoes might enter by. No tape needed. However, at times when I did not cut the screen big enough to curl it as thick as needed, I’ll use some duct tape.
  8. Adjust: Once the screen is in place, you’ll want to check that you have left no gaps that mosquitoes can enter by and also that you have left a uniform “bubble” so that the window can open without the corners of the glass salts catching and ripping the screen. You’ll just have to open and close slowly looking for the problem areas and pull those areas out with your fingers. This may seem like a temporary fix, but in my experience once you get the window installed right with enough clearance, it stays that way and keeps working even opening and closing everyday.

That’s it. Your screen should take you only minutes per window but will last a lifetime.

Let me know your comments from your installations and any feedback to improve this tutorial.


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