Architecture design software
Architecture design software is the set of programs an architect uses to draw, model and document a building, and it comes in 3 broad families, the 2D computer aided drafting tools, the 3D modeling tools, and the building information modeling platforms that hold the model and the data together. The choice among them is not a matter of taste but of stage, because the 3 families do 3 different jobs in the body of a project, and most firms run all 3. This page names the tools in each family and says when each one is the right tool for the part of the building design it serves.
The 2D CAD tools
The CAD tools in architecture are the programs that draw the building as flat lines on a screen, and they remain the base layer of every project because the construction documents are still, in the end, a set of drawings. Computer aided drafting, the practice that began in the 1960s, moved the drafting board to a screen, and the standard file for the trade drawings is still a 2D plan, an elevation and a section. The tools in this family are fast and precise, and they are where the dimensions, the room labels and the material callouts are written, because those are the notes the builder reads on site. The drawings are the output of the discipline of architecture that carries the building to the trade, and the 2D file is the one that is stamped and sealed.
The 3D modeling tools
The 3D modeling tools in architecture are the programs that build the building as a solid object in space, and they are where the design is explored before it is drawn. A 3D model lets the architect walk through the building, test the daylight in a room, and see the massing from the street, and that is the work that a flat drawing cannot do. The tools in this family range from the direct modeling programs a designer sketches in to the parametric tools that describe the building by rules, and the parametric end is where the complex curved forms of contemporary architecture are made, because a surface that a hand cannot hold is held by a parameter. The model is the thinking of the design, and the 3D file is where the form of the building is decided, before the 2D drawings are cut from it.
The BIM platforms
The BIM platforms in architecture are the programs that hold the 3D model and the data about every element of the building in one file, and they are the coordination layer of the project. Building information modeling, the method described in the Building information modeling page of this site, treats the wall, the beam and the duct as objects with properties, and the platform counts them, clashes them and schedules them. A single model serves the architect, the structural engineer and the mechanical engineer at the same time, and a clash, such as a duct through a beam, is found in the model instead of on the site. The 3D modeling tool and the BIM platform overlap, and a modern firm often works in one environment that is both, so the model is the building and the data is attached to it. The Building materials and technology section of this site is where the properties in that model are defined, and the AI in architecture page is where the model is checked.
Choosing the right tool for the stage
Choosing the right tool for the stage in architecture design software is a matter of matching the tool to the question being answered, and the 3 families answer 3 questions in order. The design question, what should the building be, is answered in the 3D model, where the form is free to change. The coordination question, do the systems fit, is answered in the BIM platform, where the model is checked against itself. The documentation question, how do we tell the builder, is answered in the 2D CAD file, where the drawing is precise and signed. A small house may be drawn mostly in the 2D file with a simple 3D model for the client, while a large public building runs all 3 in parallel, because the number of trades on the site is what drives the need for the model. The body of a project runs through all 3, and the software that serves it is the set of the 3, not a single program. The What Architecture Design Actually Means page of this site is where the design question is asked, and the tools are the means by which the answer is made and the building is built from it.