The Helsinki City Planning Department organized in spring 2010 a Townhouse Competition for the island Jätkäsaari Kruunuvuorenkat, witch is located in the west of downtown Helsinki. The disused port facilities are an important part of the urban development of Helsinki. It should arise dense urban structures that offer differentiated and optimized to our customers wishes townhouses. As part of the competition different strategies algorithmic methods examined in urban design and it was tested the external and internal influences on urban constellations and their rule-based implementation. Finally three tools have been developed - parcel generator + open space generator + form generator: with these three tools the two quarters were examined and the final structure was generated: Tool 1: Parcel Generator This generator is setting the layout of the house types in random or customized order. The percentage variation of each housing type is made also with this tool. As they are dependencies of internal house organization and the building size, the staircases are adapting to it. The generator can be feed by simple random information or by precise customized data referring the wishes of the clients. As there are also public facilities as restaurants in the ground floor at some sites, the generator will connect the ground floor of two houses and displace the position of the staircase to the side. Tool 2: Open Space Generator After transferring the housing types to this generator, the geometries will be reeded and a set of operations will be applied to the houses. First is the amount and orientation of the open space that needs a external input. This parameters are depending on the sun orientation, surrounding of the building and clients wishes. They should be adjusted individually for every single townhouse cluster. There are 2 major settings for every entity: a. Two open spaces for every house b. no open space will face the open space of the neighbor The position and size of the open space are also depending of the staircase size and position and the house width. If the house width fall below a certain limit, the open space will be 100% of the house width. Variation of different open space constellation helps finding the optimal configuration of the townhouse cluster. Tool 3: Form Generator Setting the size and voids of the house geometry, now we can let the form generator perform the roof and facade operations. The shape will be analyzed and transformed depending on the input roof- and facade types. Both types can be random- or custom controlled, but are also having two main rules they have to follow: Variate: openings are limited to the internal floor organization and will adjust according to the floor layout; Simplify: more than 3 parameters or form types are possible but difficult to handle.