Who’s the boss?

The answer depends on two considerations: your relationship with your contractor and your ability to manage the construction yourself. Renovations are expensive, so before doling out more cash, consider these angles:

From your renovator's point of view, hiring your architect to supervise construction is a terrible idea because renovators and architects share only one thing: antipathy. Sam Incardona, a custom home builder in Toronto with 30 years' experience, once told me: "Many architects think the contractor is sleazy and trying to get away with something." Beyond feeling insulted and defensive, your contractor will likely pad his bill to cover the hassle, if he takes the job at all. That's not the kind of atmosphere you want on site. So, if you trust your contractor, don't bother hiring your architect to supervise.

Unfortunately, architects may have a reason to be distrustful. Incardona's next comment was, "In some cases, the architects are absolutely right." (I tell you this even though I'm a contractor myself.) If you're not sure your contractor is trustworthy, or if he needs help staying on track and you can't provide that firm hand yourself, hiring your architect to supervise might be a good idea.
For three to five per cent of the total value of the project, your architect will monitor mid-job payments, evaluate the contractor's performance against the original plan and ensure compliance with the building code. For an additional five to seven per cent, your architect will provide full-time project management, supervise product choices, handle scheduling and act as your eyes and ears on site.

Know this, however: your architect may be just as inclined to protect his own interests – at your expense – as your contractor. On an addition I did, the architect called for a steel beam where a wooden one – cheaper, perfectly safe and quicker and easier to install – would have worked just as well. We installed the wooden beam and the architect threatened to withhold a progress payment unless we changed it, not because the wooden beam was unsuitable but because it showed the client that the original design was a waste of time and money. We were only halfway through the job, but the animosity on site was palpable and the owner didn't know whom to trust.

This brings me back to Incardona. He is now a design/build home builder who does both the architectural and the construction work. With design/build projects, there's no finger pointing between the architect and the builder when things go wrong – both the architect and the renovator work for the same company. It's a one-stop shop where the company hired takes full responsibility – from the first pencil line on a napkin to the last drop of paint on the walls. And the cost of hiring a design/build company is less than hiring an architect and a contractor.
So, my final answer: if you trust your contractor, don't waste your money hiring your architect to supervise. But if you aren't sure about your contractor, hire your architect but stay engaged. Next time, go design/build and enjoy the ride.