This is not very easy in most of the older houses we work on because the hatches and attics are too small to get rigid foam board through.
Installing knee wall attic insulation.
Here are the three keys to sheathing an attic kneewall properly.
7 staple the edges of the facing into each of the studs.
Sheathe the kneewall during framing.
Knee walls installing batt insulation.
One of the best methods is rigid foam board with sealed joints over insulation in the knee wall.
Now that the kneewall is.
The advantage here is that your knee wall is probably already insulated this way so it s just a matter of buying some foam so cheap.
Keep the attic outside insulating a kneewall and the attic floor behind the kneewall is possible but tricky.
Insert each strip of faced insulation between the studs in the knee wall with the facing directed toward the living space of the attic.
Seal all the edges penetrations and seams.
Verify insulation material is the correct width and r value.
Friction fit insulation between and parallel to the framing members in full contact with rigid backing top and bottom plates.
Bring the attic inside insulating between the rafters simplifies the air sealing details.
Insulating and air sealing knee walls unvented version.
More details online 1.
There are as many ways to do it as there are people who do it.