I don't know exactly what you mean by point cloud. But maybe you can use FUSION software for processing '.las' files containing point information for terrain analysis.
I usually work with 'Metashape' (https://www.agisoft.com/). It is a highly recommended software, but it is not free and open source. In any case, there is an educational licence (I don't know if it is possible in your case), which is quite cheap.
How do you plan to take the points? I imagine by RPAS or perhaps by ground photographs. If so, you can increase your resolution to less centimetres (depending on the size of your building). I have never worked with architectural elements, as my main subject is terrain (DTM). But in any case, you can produce an accurate 3D survey.