Willis has providers for exterior cleaning services. This refers to the cleaning of the exterior of a building, removing litter, dirt or leaves, and restoring the appearance of the building facade. The services may be offered for both residential and commercial buildings. The cleaners may specialize in stone restoration, stone conservation, bronze cleaning and restoration, graffiti removal and protection, glazing, gutters, fascia, cladding, paving, swimming pools or patio furniture, or may be more generalist. This enhances the esthetic appeal of the building. Before the service is carried out, the provider would inspect the building, assess the cleaning needs, and give a price quote. The work is done after the charge is agreed upon. Cleaning is done using water, or other chemicals. Care is taken to see no damage is caused to the building materials. Removal of surface oxidization, dirt, mold and other contaminants is also effected. One should opt for non-corrosive, environmentally friendly cleaning products. Maintenance packages (wherein regular cleaning services are carried out) may also be bought. The cleaners may be certified in their particular line of work in Willis.