You have a couple of insulation options, depending on how your home was constructed.
Drill and fill. You might be able to drill small (1/4-inch) holes in the brick mortar joints and inject expanding foam between the brick and block.
- You'll need to make sure that the foam is suited for this type of application since this space is also part of the drainage system for water that penetrates the brick structure.
- If properly installed, you may get a continuous insulation barrier on the exterior of the block walls.
Fill the block cores. You may also be able to fill the block cores with polystyrene beads. If the block cores are accessible from the top (in the attic), they may be able to pour foam beads directly into the cores.
The drill-and-fill system may make the most sense for your climate zone.
- A continuous thermal barrier over the block walls would be more effective at reducing energy costs than core filling (only).
- A combination of both systems is best if the cost is in the budget.
Good luck in reducing your energy use and improving the comfort level of your home.