Demolition Tip: Shut off the HVAC

By: Mark Clement , Contributing Writer
In: Old Houses, Home Improvement Tips, Old House Musings

So you’ve taped off every opening, hung plastic everywhere. You’re even blowing a box fan out the window or using an air cleaner. That’s supposed to manage the airborne material. Looks like it’ll work.

Now it’s go-time.

You drive your demo bar into the plaster and lath, start sanding all that drywall, or start making all those zillion cuts for the new trim or floor thinking the rest of the house is completely cordoned off from dust.

No problem, right?


At the end of the day you re-enter the living space, say to and run up to your office or into kid’s room and find a fine coat of dust has fallen like snow. It’s everywhere on everything.

What the –

Layer One: Your spouse may well be livid. Welcome to the old house shuffle.

Layer Two: You did everything your neighbor told you, that you read here, or saw on DIYNetwork but that’s all fine fettle…you can’t explain the dust. And you know you have to–as you’re cleaning it up!

Old House Suspect #1: Your HVAC Unit

While there are a zillion and one culprits in an old house–everything from balloon framing to missing shoe molding–one of the usual suspects is your HVAC unit. If you left it on–heating or cooling, it doesn’t matter–it may well be your primary culprit.

And if you’ve been victimized by this shell game, you’re not alone. See, your HVAC system sucks air from the house back into itself through vents, conditions that air, then sends it back out into the house. If the air is full of dust, well the dust goes along for the ride.

There are several ways to minimize this common problem–and not kill your system while you’re at it:

  • Do everything you did–plastic, fans, et al.
  • Shut your HVAC off during high-dust activities
  • Also, tape off every return vent (the HVAC’s intake or supply vents. You can tell which are returns because the air on these gets sucked in) on the floor you’re working on.
  • Adjust your expectations. Dust can be managed, but rarely controlled without massive precautions. Expect some dust no matter what. Spouse too.
  • Fans work to a degree but aren’t suitable for all climates or necessary for all jobs. Air cleaners work better for many projects.
  • Last step: replace your HVAC filter to help keep your system clean and running efficiently.

These steps should take you a long way towards cutting down on the snow in your forecast.