Ilongot live in thirteen named dialect groups each with an average population of 180. Each of these groups includes several settlements, which in turn are made up of four to nine households (five to fifteen nuclear families, forty to seventy people). When people move to a new area, their houses are built in clusters, but as farther, more widely spaced new fields are cleared, houses are built near the new fields, and the settlement pattern becomes dispersed. Where there is missionary influence, houses are built clustered near runways. Houses sit on pilings up to 15 feet above the ground, and have walls of grass or bamboo. There are no inside walls; each nuclear family (there are one to three per house) has its own fireplace. There are also temporary field houses.