The big problem with the original single skin recessed lighting fixtures is they get so hot they might ignite material that touches them.
For that reason, when recessed lighting fixtures were first introduced, either a wood box or a chicken wire cage was typically built around them to keep anything from touching them.
Then double fixtures for recessed lighting came out.
With these fixtures the inner wall still get very hot , but there is a sizable air gap between the inner wall and the oute rwall so the outside of the can gets warm, but not hot.
When selecting recessed lighting cans, be sure to check the label to ensure the can you buy are rated IC, which is the designation for insulation contact.
The label is inside the can and can be seen when the bulb is removed (as in the picture).
And speaking of recessed lighting for your home ….. we would love to install some for you when you live in or near Los Altos.