Fly screen mesh was once fairly thin and fragile. It kept insects out while allowing light and air inside. But mesh and the functions it performs has developed over time. High end screen mesh is now used to keep human intruders out, providing security. It also works as a safety feature, preventing infants or pensioners from falling out windows.
Some types of screen are:
This is less of a mesh than it is a perforated sheet of solid metal. The ‘mesh’ effect is achieved by creating holes in an aluminium sheet. These holes are large enough to permit airflow, and moderate light, but small enough to keep out flying insects.
This works well in combination with a lighter screen. The diamond grill provides strength to keep the house secure. The lighter mesh keeps insects out. This diamond grill should be solid rather than criss-crossed bars of metal.
This is a common and inexpensive type of mesh screen. You will see this on many older windows and doors. It is fine for keeping insects out, as well as pets indoors. But it can be easily broken with brute force.
This screen will combine will with Diamond grill or decorative pattern grill.
A modern solution. This is rust proof under most circumstances, though it can be damaged in salty beach atmospheres. Modern stainless steel can be powered coated to give it a wide variety of colours.
Steel doors tend to be quite heavy.
An older alternative for metal door and mesh, but one that lasts quite well. Aluminium will not rust, unless exposed to salty or corrosive conditions. It tends to be the same matt silver colour, but it can be coloured through anodization.
Aluminium doors are quite light. But they are not always strong.
One good combination uses aluminium mesh and a stainless steel door. But it is not possible to weld these different metal together.