Heads above obstruction

[FIVE50]

Unobstructed Beam and girder construction. Corrugated metal deck. Parking garage. There is duct that is over 4’ that will have coverage under it but is only 12” between the top of duct to the deck. Is there a minimum distance from deck to top of obstruction that you don’t have to put heads above an obstruction ?

 

[UFT12]

I doubt there is guidance on this specific case in NFPA 13. It is important that sprinklers be installed as high as possible for prompt activation.It is also important that the first 18 in (457 mm) below the sprinkler deflector be free of solid continuous obstructions. If this is not the case and assuming the obstruction cannot be brought lower, one should check from a practical point of view whether it is feasible to install the sprinklers in the narrow space. For example, are they accesible? My personal belief is that if there is accessibility and sprinklers can be installed (12 in dont seem that little) then they should unless you can demonstrate that it is really bothersome for some reason.

 

[FIVE50]

Great answer thank you!