Exterior solid wall insulation

The fact that solid walls haven't a cavity in their core, doesn't make them more energy-efficient. On the contrary: solid walls are typically very energy-inefficient. The heat (and the cold) travels better without a gap within them... That's why exterior solid wall insulation is vital.

For cavity walls, see: Types of Cavity Wall Insulation

External vs. Internal solid wall Insulation

In new homes, the insulation of solid walls should involve the insulation of the core of the bricks (in brick walls) and also a continuous blanket of insulation over their external surface.

Such insulation (something equivalent to insulated sheathing in other types of walls) cal help reduce condensation and prevent dampness, and it is better than inside wall insulation. However, in existing homes, inside wall insulation can be considered with advantage in some cases. See: Inside wall insulation.

Traditional Solid Walls insulation products

Clay-based bricks walls, or concrete and other masonry block walls are often cavity walls. They have a gap/cavity between the two layers of materials that acts as a barrier, reducing energy flow through the walls. Since solid walls haven't such gap, unwanted energy losses are higher, making their insulation truly crucial.

Traditional materials such as Warmaline are largely used on solid wall insulation.

That's basically equivalent to use a non-branded board of expanded-polystyrene with the convenient thickness.

New Solid Walls Insulation Materials

But there are now other alternatives for exterior wall insulation.

Manufacturers such as Dow Chemical are offering insulation solutions for concrete and masonry walls, based on a light/thin foam sheet (polyisocyanurate sandwiched between a continuous sheet of aluminum foil...).

Polysocyanurate insulation

Both the new polyisocyanurate sandwich and the more traditional expanded polystyrene insulation have excellent barrier qualities and offer extreme durability and high thermal insulation (polyisocyanurate offers the highest insulation value among foam products).

Their thin profile also makes them relatively easy to apply in exterior wall insulation.

installation

Exterior wall insulation varies with the type of material.

Polystyrene foam boards can be installed using wood furring strips attached to the walls (they provide the nailing base to the boards). Once a first layer of boards installed (between the strips), a second layer of insulation foam is installed over them (before the finishing and painting). In some cases, builders also attach a wire lath to the second layer of insulation to reinforce the overall strength...

The installation of proprietary insulation foams should follow the manufacturer's instructions. A common method involves gluing the insulation boards to the masonry walls, with the help of a construction-grade adhesive; wood furring strips are then placed over them, using masonry nails and screws, adequately spaced.

Gypsum board (applied over the insulation material in accordance with manufacturer's instructions) is a common finishing.

Costs

The prices of exterior wall insulation differ a lot, and vary with the type of material.

Traditional insulation products are cheaper, but they demand higher installation costs and can be less energy-efficient.