Framing @ Rooftop Unit Openings

[mrengineer]

This is a survey: With steel framed roofs, do you require framing around the supply air and return air openings in addition to providing framing for the RTU itself?
Thanks

 

[JAE]

Any deck opening larger than 12" - we require supplemental framing.

 

[UcfSE]

Same as JAE here.

 

[SperlingPE]

yes

 

[apetr26542]

Usually just call for the framing around the unit if the openings for the unit are contained within this frame, other wise it is any opening >12".

 

[denoid]

I agree with the above responses...you need to support the free edges of deck, so as not to cantilever too far beyond joist/beam.

 

[MWPC]

Usually both but I see a lot of opening frames laying around the jobsites after the RTUs are in place. Coordination of the opening must be a problem.

 

[MikeE55]

we usually see framing under the curb only. The deck under the unit could be completely removed - it has no load but self-weight. Correct?

 

[jike]

I agree with providing frames for openings greater than 12". For deck openings between 6" and 12" we require a 16" flat plate extended 6" beyond the opening on all sides and screwed to the deck at 6" oc around the perimeter.

 

[mrengineer]

MikeE55:
Here are some reasons I can think of to not remove all of the deck:
1) Lateral support of framing members, bar joists in particular.
2) Safety hazard during construction? (I an not sure at what stage of unit installation they would cut the holes).
3) Good to have as much of the roofing continuous as possible due to sound considerations?

 

[jen4950]

we have a typical detail

 

[Lutfi]

YES

Regards,
Lutfi