Thermal Efficiency of Brick Houses Vs. Wood Houses

Thermal Efficiency and R-Value

• Building materials, such as brick and wood, have an R-value. This is an assigned numeric value that measures the material's thermal efficiency for retaining heat. Engineers and independent agencies test materials to determine their R-value. Builders use the R-value to determine how much and what type of insulation to use for maximizing the energy efficiency of a home or building.

Brick Home

• A 4-inch block of common brick has a thermal efficiency R-value of 0.80 while a 4-inch piece of brick veneer has an R-value of 0.44, according to R-value tables compiled by Colorado Energy.org. However, to more accurately determine the thermal efficiency of a brick home, you have to factor in additional materials, such as the framing components, studs, sheathing and insulation. This combination is referred to as the “whole wall” and the “clear wall” thermal efficiency R-value. The whole wall value takes into account windows, doors and any object that reduces heat retention while the clear wall value relates to solid walls that do not have any other element, such as a window or door. For example, a whole wall in a brick home might have an R-value of about 3.6, and a clear wall might have an R-value of 3.5 or higher.

Wood Home

• Wood homes are those that have exterior walls made of wood siding materials, such as plywood. The R-value for 5/8-inch plywood siding is 0.77, and the R-value for 3/4-inch plywood is 0.93. A wood home constructed with a wood frame, studs, cellulose insulation and 1/2-inch foam sheathing might have an R-value range from 12 to 15 or higher. The higher the R-value, the higher the energy and thermal efficiency of the home.

Similarities

• Brick and wood, in their “raw” state, start with low thermal energy-efficiency R-values. The whole wall thermal efficiency will lessen with either type of material when you factor in the addition of windows and doors. However, the final thermal efficiency of each home will increase based on the types of materials used to insulate the home and create the final envelope for the home from the exterior to the interior walls. As a result, you can build and insulate a home made of either type of material and make them relatively equal in terms of thermal efficiency. You can also add energy-efficient materials, such as windows and doors, and retrofit existing insulation to improve the thermal efficiency of a brick or wood home.

Differences

• A brick home will be less impenetrable in terms of natural and man-made circumstances that could lessen its thermal efficiency. A brick home will better withstand natural seasonal occurrences, such as snow, rain and wind, in comparison to a home with a wood exterior. Brick is also less prone to pull away from the exterior walls and, therefore, reduce the home’s overall thermal efficiency. Wood siding, on the other hand, can more easily tear away from the exterior, by natural or man-made occurrences, and thereby expose the cavity of materials to climatic conditions, such as heat, cold and water, reducing the home’s overall thermal efficiency.