The Science of External Wall Insulation: How It Works

The term “external wall insulation” (EWI) refers to the practice of adding insulation to the exterior of a structure before covering it up with a weatherproofing membrane. Most often, this is done in older buildings that either don’t have hollow walls or can’t be retrofitted with cavity wall insulation. The usage of EWI is not limited to just residential structures, but may also be implemented in commercial and industrial structures.

The Science of External Wall Insulation

Using EWI, you can keep your home toasty warm in the winter and refreshingly cool in the summer by limiting the amount of heat that escapes the structure. A building loses heat through its walls, roof, and windows; EWI attempts to lessen this heat loss through the walls. To keep warm air inside a structure, an insulating layer is typically installed on the building’s exterior walls.

How Does EWI Work?

Exterior wall insulation, or EWI, is installed by fastening insulation boards to the building’s exterior. These boards can be found in a variety of thicknesses and insulation R-values, and they are often fabricated from polystyrene, mineral wool, or polyurethane foam. Render or cladding is applied over the insulation boards to create a protective layer and give the building a finished appearance.

Boards used in EWI are insulated with air, which is a poor heat conductor, hence the insulation is effective. As less heat may escape through the insulation as a result of this barrier, the interior of the building will remain more comfortable year-round.

EWI not only helps to prevent condensation from accumulating on the inside walls of a structure, but it also reduces heat loss. This is due to the fact that the insulation layer acts as a barrier, stopping the warm, moist air from inside the building from coming into contact with the cold exterior walls. This helps to keep the inside walls dry and mold-free, which is important for people’s health.

The Benefits of EWI

A Rise in Thermal Efficiency

The enhanced thermal performance of buildings is one of the main advantages of EWI. EWI can greatly improve a building’s insulation value by decreasing heat loss through the walls. Occupants will enjoy a more pleasant climate inside the building year-round as a result.

Lowered Energy Use

EWI’s capacity to lessen energy use is a further major advantage. EWI can drastically cut down on the amount of power needed to heat or cool a building by enhancing the structure’s thermal performance. EWI is a greener alternative because it lowers energy costs and carbon dioxide emissions.

Increased Comfort

When applied to buildings, EWI can also improve residents’ level of convenience. EWI generates a more uniform temperature throughout the building, which is especially helpful for people with respiratory issues or allergies by reducing drafts and getting rid of cold patches. More than that, EWI can serve as a sound barrier, lowering ambient noise and contributing to a more tranquil atmosphere.

Improved Building Durability

Insulating the exterior of a building is another way to make it last longer. EWI can aid in preventing moisture intrusion, which can lead to structural deterioration over time, by protecting the building envelope against weather and environmental harm. In addition to preserving building materials from wind, rain, and hail, EWI also helps keep them warmer.

Increased Property Value

An additional advantage of EWI is that it can raise the market price of a home. EWI can boost a building’s market value by increasing its comfort, longevity, and energy efficiency. As a result, investors and homeowners may see improved returns in the form of more rental income and higher property values.

Customizable Appearance

The aesthetics of a building can be altered with the help of EWI as well. EWI can be given a variety of aesthetic treatments, including render, cladding, and brick slips, all of which can be modified to meet the needs of specific clients. Hence, EWI can be employed to give a building a more polished, contemporary look.


The environmental and health benefits of EWI can be better understood if we first look at the science underlying it. There’s no better place to go than Luca Line Services if you want to learn more about the advantages of EWI. Luca Line Services is dedicated to assisting homeowners and builders in their pursuit of energy efficiency through the installation of exterior wall insulation.