Building on a slope is about creating a stable, flat foundation, either dug into the slope or supported above the ground level, on which the house can be built. Building on a sloping lot can be much more expensive and time consuming than building on a flat lot. Check with your local municipality as to what the planning rules and building codes are that relate to the lot. In densely populated areas there are often restrictions placed on developing sloping sites that will restrict the size and shape of your house. Check with your local utility companies as to availability of water, gas and electricity for your lot. If the sloped lot has not been built on in the past, even in large cities, some utility services may not have been installed. Obtain a soil report from a geotechnical engineer. A geotechnical engineer will take soil borings at different locations on your lot to assess the soil stability and composition. Engage a structural engineer to design your foundation system and structure. The structural engineer will determine the size and type of foundation you will need based on your house design and the soil report. Work with a contractor or builder who is experienced with building on sloped lots. Sloped lot foundation systems often include retaining walls that require earth excavation, or deeply drilled piles and caissons. Budget extra time and money for your building project compared to building on a flat site.