I usually use wide angle lenses for this sort of photography, however a wide open lens can and will cause distortion. While this is not a huge problem for showing the visual aspect of the building, the proportions are completely lost.
Canon has a line of Architectural compatible lenses, the MPE-65 or something like that, I believe it is called. It basically allows you to focus on the structure, but by using two knobs on the vertical and horizontal planes, you are able to reduce and reposition the glass elements to remediate that distortion.
It all depends on how pro and detailed the work is. If he just wants photos for updates, then you are good. Many times, if the photos are for catalogs, samples, then you want to present distortion free photographs.
Hope this helps, my 2 cents anyways.