The element earth is the calmest of the elements.
People need his strength, stability, for their harmony. The element earth also cleanses, of course, but this process is slower and gentler than with the other elements. Step by step the element attracts the energies, cleanses them and gives back clean, nourishing energy.
The salt symbolizes this power of the element earth. You probably know this power from salt baths or the sprinkling of salt in winter. Salt absorbs, it attracts energy. For this reason, the salt is valuable for a cleansing ritual.
By consecrated salt I do not mean, of course, that you should have the salt blessed by a pastor, but that you ask the salt to attract and absorb the stressful energies and emotions in the walls.
If that is your intention and belief. That’s how it will happen.