Depending on the structure, cavity gaps can be insulated using polyurethane foam, or loose-fill insulation.
The main purpose of cavity wall insulation is to stop air movement within the structure. Insulating wall cavities provides significantly better heat retention without altering the building’s exterior finish. Liquid or loose materials are injected or blown into the cavity through small openings, filling all voids while leaving the external facade unchanged.
Older residential buildings were often constructed with an air gap between the inner and outer masonry walls. These cavities can be effectively insulated using injection polyurethane foam, or blown loose-fill insulation materials.
Filling the cavity is especially beneficial when planning external wall insulation, as it improves overall performance and prevents heat from escaping through hidden gaps.