Short answer: never.
More elaborate answer: the reason it is important to get an architect involved in a project as early as possible is because architects work on buildings and planning every day. We do it for a living. We know what to do with a site, whether it be vacant land or a parcel with an existing building that needs to be demolished. We know how to guide you through the code-filled maze that is getting buildings approved so that your project can be as successful as possible.
Some people think going to a civil engineer first is the answer. My opinion is that a project should begin with an architect simply because we see the world through architect’s eyes as opposed to the eyes of an engineer. What’s the difference you ask? I feel that architects tend to see the world in terms of design and the potential for design, whereas I feel that civil engineers see the world more in black and white. I see civil engineers (as well as engineers in general) more as scientists where I see architects more as artists. I don’t think this is a good or bad thing (please don’t get this misconstrued – I love the work engineers do!). With this knowledge in mind, I feel it only makes sense to start with the artist when you have a blank canvas (your site).
Example 1: I was working on a project for around 300 duplexes (two residential units connected). I received a plan from a client’s civil engineer that had all the assumed property lines laid out. The owner said, “Ok Mr. architect…gives me 3 separate plans for duplexes that I can stamp out 100 times each. I want them all to have three bedrooms.” Well that sounds easy enough, except the problem was as soon as we got some plans into the computer to scale, we quickly came to the conclusion that ANY 3 bedroom unit was impossible due to the way the property lines ran (they were too close). We would only be able to fit 2 bedrooms and a den into the units which would lower the value of the units greatly. We ended up having to go back and change the site plan. I hated doing it because I knew the civil engineer had spent a lot of time on his calculations, but at the same time it needed to be done. When we changed the site plan, the number of units went down from 300 to about 280 units. There was no way around it…it was either that or have two bedroom units which the owner didn’t want. If he would have come to us first we would have been able to tell him how many units he could fit on the site before he hired the civil engineer. This would have saved him time, energy, and money.
Example 2: A client brought in a site plan prepared by a civil engineer showing 58 4-bedroom homes. We were able to tweak the plan to give the client 4 more units. That is a lot of money people! The reason for this is because we were coming at the problem from a creative standpoint. We came up with an unorthodox way of manipulating the plans to work with the site.
The ideal way to approach a project is with an architect AND a civil engineer because then you’d have two professionals viewing your site from two different (both important) view points. This usually doesn’t happen though unless there is something about the project that makes it unusually complicated.