Basics

• Cinder block walls offer many advantages. That includes the fact that they are fireproof and weatherproof. They are precast, hollow blocks of a uniform size. You build a cinder block wall by stacking the blocks side by side and then on top of each other, using concrete mortar to hold the blocks together. Cinder blocks have a medium-to-coarse texture and are dark gray in color. In addition, they have a slightly higher thermal insulation value than concrete blocks.
  
  

Perlite

• Perlite pellet insulation is a natural substance made from a volcanic mineral. Perlite is poured loose into the hollow cavities of cinder block walls. Using perlite has some advantages. When poured into the cavities of a cinder block wall it provides insulation between the exterior and interior of the cinder block. However, you can also install furring strips against the cinder block wall to put up drywall or paneling and then pour the perlite into that space. Either way, perlite fills all the voids and does not settle. Two other types of loose insulations, vermiculite pellets and polystyrene beads are basically the same as perlite.
  
  

High-Pressure Foam

• Foam is another type of insulation used inside cinder block walls. Contractors fill the hollow interiors of cinder blocks with foam inserted under high pressure. When it dries, it is solid and fills all the voids. According to the United States Department of Energy, high-pressure foam is better than loose, poured insulation, such as perlite. However, neither high-pressure foam nor perlite offers a high insulation value when used to fill the cavities of cinder blocks. That is because it does not help to reduce the movement of heat over the surface of either the interior or exterior of the blocks and the mortar joints.
  
  

Rigid Foam Insulation

• Rigid foam insulation is installed over the interior of a cinder-block wall. That means it covers the wall from the floor to the ceiling. Therefore, it provides a higher insulating value than loose insulation fills such as vermiculite pellets or high-pressure foam that only goes inside the cavities of the cinder blocks. In addition, since rigid foam insulation is waterproof, you can also install it on the exterior of the cinder block wall between it and the exterior siding. However, it is subject to infestation and damage from insects such as termites or carpenter ants.