Development botch-up

This looks farcical, but it's what can easily happen when you don't have a competent person overseeing all aspects of your project.  (How can you drive into your garage?)

Blocked botch-up: New Hobsonville Point garages built directly behind rainwater pits - NZ Herald

It’s what happens when the design is fragmented into various components and handed out to separate consultants (as it often must be), but there’s nobody having oversight to check all the components are integrated. Contrary to the developer’s comments, it more likely reflects badly on the developer not having a good project manager in place, rather than their various specialist consultants.

You cannot engage various specialist consultants, no matter how good they are, and leave them to it.  They generally only focus on their part of the project, not the total picture.

This is an extreme example.  Someone overseeing the project, even someone who was unskilled in development could have picked this up -  provided they could at least read plans, and had the time to review them.

So first thing I'd suggest as a minimum, is that you as the project owner should at least oversee things.   Even if you don't know development or construction well.  Don't assume your separate consultants or contractors will talk to each other and avoid issues like this.  Often they don't. 

The best solution though is to engage someone highly experienced in your field.  Even if you can avoid the more obvious problems like the above;  other less obvious problems will arise, and unnecessary cost will usually creep in, often without you even knowing it.  The savings and efficiencies  a highly competent person will achieve will usually far outweigh their fees.