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Vaulted Ceiling iStock

Tom Silva replies: In some houses, it’s a fairly straightforward project; in others, it’s practically impossible. I don’t know enough about your house to give you a specific recommendation, but I can help you figure out if it’s worth having a contractor come take a look. The more hurdles you find, the more extensive, and expensive, the job will be.

How to Vault a Ceiling

  1. First, head to the attic. If you see a complicated framework of 2x4s held together with perforated metal plates, your roof is framed with trusses. You’ll have to remove the entire roof structure to vault the ceilings. But if it’s framed traditionally with big lumber rafters, the roof can stay in place.
  2. Second, measure the depth of the rafters. Anything less than 5½ inches isn’t deep enough to insulate sufficiently, unless you use spray-in foam. With batt insulation, you have to ­allow for a 1-inch air space to ventilate the ­underside of the roof. Spray-foam insulation doesn’t need an air space.
  3. Third, check for mechanical complications: ducts, plumbing vents, HVAC equipment, and wiring. Anything in the area to be vaulted will have to be relocated. You’ll need an HVAC contractor to determine whether your heating system can handle the increased volume of a room with a vaulted ceiling. ­Also, before you start the work, consult a—structural engineer to make sure the collar ties are in the right place to prevent the walls from spreading apart—after the ceiling joists are removed.
  4. The carpentry itself isn’t that difficult. Once the collar ties are fastened horizontally between opposite pairs of rafters, 1x3s are nailed to the underside of the ties to provide solid backing for the new ceiling surface.