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Question about roof top HVAC

William Scott

Registered User
Jun 30, 2019
Brooklyn New York
I own a property in Brooklyn New York and the 3-ton Mitsubishi HVAC installed on the roof is sitting on a wooden structure. All of the other properties I own have HVACs mounted on steel beams. Does any one know if this is a code violation (mounted on wood instead)? I'm a little worried. -- Thank you.

Mark K

Platinum Member
May 12, 2010
There is no inherent reason that a mechanical unit cannot be installed on wood. So the use of wood in and of itself does not indicate whether you have a problem still you may want to ask several questions particularly if there is the possibility that the unit was installed on the roof with out any structural engineering input.

Is there any sign of distress or deflection in the building due to the mechanical unit? are the wood members rotting? Try to stick a screw driver into the side of the wood member. If there is signs of rot retain a structural engineer.

Mechanical units are often are labeled as to their tons of refrigeration which may be different from the actual weight of the unit.

In general if you want more assurance hire a structural engineer to look at the installation.


Nov 28, 2009
Poconos/eastern PA
IMC 302.1 Structural safety. The building or structure shall not
be weakened by the installation of mechanical systems.
Where floors, walls, ceilings or any other portion of the
building or structure are required to be altered or replaced in
the process of installing or repairing any system, the building
or structure shall be left in a safe structural condition in
accordance with the International Building Code.


Chief Cook & Bottlewasher
Oct 16, 2009
Palm Beach County Florida
There may be issues with wind loads and how the unit is connected. If you are not in an area subject to higher wind loads, you may not be familiar with these requirements.