All of our custom home projects have a complete set of structural drawings and calculations, prepared by a licensed structural engineering firm.

I believe you live in Canada, so this doesn't necessarily apply, but in most of the U.S., if you can get it off a table in the IRC, then it doesn't need an engineer. Some things still do such as a soil test for footings, extra tall walls, complicated framing that the review department doesn't want to mess with, special zones for earthquakes or wind, etc.

Fred's right. Even here in California we have typical design for standard things like footings and retaining walls. The designs are locally approved and can be called out out the plans as such. Soils reports by geotechnical engineers are almost always required if you use "typical" details because of the variations in soils, the hills and the earthquakes. We find it easier and usually less expensive to hire a structural engineer for any in house design projects. Plans that come to us without an engineer's stamp are rare, although a licensed architect can fulfill that role legally.

And if everything is already clearly marked on the plan, beam sizes, etc, etc, per code, then an engineer really doesn't cost that much for the extra assurance. And it may even save you more than it cost in time spent at the building department.

One guy quotes us 4500 plus extras! Lame. But found another at 2500 :)