It depends on how your property is zoned.
First, check the Yelm Zoning Map to find your properties zoning classification, then look in the Yelm Municipal Code, Chapter 17 - Zoning for that district. It lists allowable uses as well as density and design requirements. Generally speaking, the residential zoning districts allow for single family and multi-family dwellings and developments. Uses that are accessory to a home are also allowed, such as storage buildings and garages, in home day cares, and home occupations. There are permit requirements for many uses, so check with the Community Development Department first. Yelm’s commercial areas are divided into four classifications, from small and low impact uses in the downtown area, to large commercial uses at the edges of town. Yelm also has a small industrial zoned area for manufacturing and other industrial uses.