Retractable Mosquito Nets: How Roller Screens Work and Where They Fit

Inside the cassette is a tube with a coiled spring in it, and the mesh is wound round the tube. As you pull the mesh out by its handle bar, the spring winds tighter. At the far side of the opening, the bar hooks into a latch or a magnetic catch and holds the mesh taut across the gap. Release it, and the stored tension winds the mesh back into the cassette. Better screens have a brake or damper so the mesh returns slowly instead of snapping back and striking the cassette.

The edges of the mesh run in two channels, one on each side of the opening for a pull-down screen, or top and bottom for a sideways one. Those channels do two jobs. They guide the mesh in and out, and they hold its edges so insects cannot get round them. Many screens have a bead or strip along the edge of the mesh that runs inside the channel, so a push on the mesh does not pull the edge out. Brush seals along the channels close the last gap.

Pleated screens are often sold under the same name. They have no spring. The mesh is folded into pleats between a top and bottom guide, cords through each fold keep it even, and it stays wherever you leave it: fully open, fully closed or part way. That makes it easier to use on a wide door, and it is the type we fit most often for French doors; see our pleated mosquito nets.

A vertical screen has its cassette at the top of the opening and pulls down to latch at the sill. It suits windows, because the cassette hides neatly under the lintel or inside the reveal, the mesh falls with gravity, and the latch sits at a comfortable height on most windows. On a tall window, the bar can be reached with a short pole or a pull cord. It is the cleanest way to screen a window that you want to look completely unscreened by day.

A horizontal screen has its cassette at one side and pulls across. It suits doors, because you can walk through when it is open, and closing it is one movement across the doorway. Pairs of horizontal screens can meet in the middle of a wider door. The trade-off is the bottom guide: a horizontal screen needs one, though it can be very low.

Width and height decide which works. A spring roller wound with a very wide sheet of mesh struggles to keep it even and taut, so single roller screens have practical size limits, and very wide doors are usually better served by paired screens or a pleated net. Ask any supplier for the maximum width and height of the system they propose, and be wary of one that stretches a single screen across a wide opening.

Wind is the main test of a retractable screen. A gust pushes the middle of the mesh, and the mesh tries to pull its edges out of the side channels. On a well-made screen the edge beads and deep channels hold it. On a lighter screen the mesh pulls free at one side, which installers call a pop-out, leaving a gap and, often, a mesh that will not wind back properly until it is reset.

The IMD's climate summary for Goa describes winds strengthening from the west and south-west between June and August, and monsoon thunderstorms sometimes accompanied by squalls. A sea-facing roller screen on an upper floor sees all of that. Where a window faces the prevailing wind directly, choose a screen with retained edges and a sturdy latch, or consider a framed sliding window net, which is the more robust choice for exposed positions.

The simplest protection is habit. When the wind gets up, close the glass and let the screen retract behind it. A screen stored in its cassette through a storm cannot be blown out of its channels, and the mesh lasts far longer for it.

The side channels and bottom guide are where a retractable screen picks up trouble. Sand blown in from a beach path, grit from the road, dust and dead insects collect in them and grind against the mesh edges and the bar. Salt dries in them as a crust. The screen starts to drag, then sticks part way, then winds back crookedly.

Near the beach, run a vacuum crevice tool down each channel every couple of weeks in the dry season, wipe them with a damp cloth, and rinse the mesh with fresh water when you rinse the windows. Do not oil the channels: oil holds sand and makes a grinding paste. If something is needed, a light dry silicone spray, wiped off the mesh, is the safer choice.

Fixings matter as much as cleaning. The Australian Stainless Steel Development Association advises grade 316 stainless, or equivalent, as a minimum within five kilometres of the surf, because lower grades stain and corrode in salt air. The screws holding the cassette and channels should meet that standard, or they will streak and seize. Before the rains set in over Goa, around the first week of June according to the IMD, clean the channels, check the latch and make sure the screen winds smoothly. Our guide to cleaning mosquito nets covers the method in more detail.

Retractable screens are at their best on view windows. A window that frames the sea, paddy fields or a garden is the reason the room was built that way, and a sliding net parked over half of it all day spoils the point. A roller screen hidden under the lintel leaves the view untouched until dusk.

They are also the right answer for many heritage openings. The tall windows of an old Goan house, with their timber frames, fanlights and shutters, often have nowhere to park a sliding net, and the proportions matter. A slim cassette tucked inside the reveal, or a pair of pleated screens, can be added without changing how the window reads. Our guide to restoring an old Portuguese house covers the wider care of those windows.

Windows opened mainly in the evening, guest rooms used occasionally and casements that open outwards, where you need to reach the handle past the screen, are other good cases. Retractable screens are a poorer fit for doors that dogs use, rooms where small children will pull at the bar, kitchens where grease settles on the mesh, and any opening used dozens of times a day. For those, a framed net is the better tool. The mosquito net chooser lets you compare them on an opening like yours.

Every screen in the house still has to close its opening fully to work. The NCVBDC's vector control compendium describes screening as a physical barrier that belongs on all openings, including windows, doors and eaves. A retractable screen left half wound in, or one that no longer latches, leaves exactly the gap it was bought to close.

Springs weaken. After years of use, a roller screen may stop winding fully home, or wind back slowly and unevenly. Some systems allow the spring tension to be adjusted, and some let the roller be replaced inside the cassette. Others are sealed, and a tired spring means a new screen. Ask before you buy whether the spring, mesh and latch can be replaced separately, and keep the details of the system so a repairer can source parts.

Torn mesh on a roller screen is harder to repair than on a framed net, because the mesh has to wind smoothly onto the roller; a patch makes a lump that catches. Small holes are often better left until the mesh can be replaced as a whole.

Sometimes the better repair is a different screen. A roller screen on a busy door that pops out every monsoon, or one on a sea-facing window that has seized twice, has told you it is in the wrong place. A pleated net, which has no spring and stays where you leave it, is often the natural replacement on doors. On an exposed window, a sliding net is sturdier. Our net repair and re-meshing visits look at exactly this question.