Managing our whole-home renovation in Hamilton — GC vs self-managed, what we chose and lessons

We did a whole-home renovation on a 1962 Hamilton bungalow — essentially gutted it. Shared walls, original plumbing, knob-and-tube wiring throughout, vermiculite insulation in the attic. We tried self-managing the trades and switched to a GC midway through. Sharing the honest story.

The project:

  • Full gut of kitchen, two bathrooms
  • Basement development
  • Attic insulation replacement (vermiculite removed first — asbestos present)
  • Knob-and-tube full replacement throughout
  • All new plumbing (galvanized removed, copper and PEX throughout)
  • New HVAC (forced air, replaced old gravity furnace)

First 3 months: self-managed
I hired the asbestos abatement company directly, then the electrician, then the plumber. This worked fine for sequential trades.

Where it fell apart: the HVAC contractor needed to do rough-in at the same time as the plumber. I couldn’t coordinate their schedules. We lost 3 weeks because they couldn’t book the same window.

I also had zero leverage when the plumber went over his estimate by $6,400 — he claimed “unforeseen conditions.” With a GC, this would be a GC-to-subcontractor dispute, not a homeowner-to-subcontractor dispute.

Switched to a GC at month 4:
GC charge: 18% markup on remaining trade work. I handed over remaining budget: $88,000 in remaining trade work.
GC markup: $15,840
What I got: the project finished 6 weeks later on schedule. Zero more coordination nightmares.

Total project cost: $248,000
My estimate when I started: $180,000.
Overrun: $68,000. Most of the overrun was discoveries: knob-and-tube was far more extensive than estimated, the plumbing had far more galvanized than expected, and the vermiculite abatement cost doubled from the original estimate.

What I’d do differently: Hire the GC from day one. The 18% markup is real money — but the loss of 3 weeks to scheduling issues cost me 1.5 months in a rental suite at $3,200/month. Net wash.