I am a project designer working on K12 education projects in WA.
On a current high school project I would like to install a fairly standard act ceiling grid but leave out tiles to give the impression of a greater volume. We are proposing to use 2'x6' fiberglass core tiles from a well known ceiling manufacturer set into their standard grid suspension system. On all four sides we will install 12" cross tees creating the effect of an 'open' ceiling. I haven't worked out the exact proportions but it looks like 2/3 ceiling tile and 1/3 open to above. This is a wide corridor situation which we are designating as shared activity space.
Ceiling height will be 11'-0" with bottom of deck at 13'-6"
Light fixtures and importantly in this context, sprinklers will be installed in the 12" gaps between the ceiling tiles at or just below ceiling level.
My question is - will we also be required to install sprinklers above the ceiling?
I'm not sure if i'm dealing with concealed spaces, an open grid ceiling or something not clearly defined in NFPA13
I don't think this qualifies as an open grid ceiling as we fall short of the 70% area but reference to sprinklers within this section seems to assume you want to install them above the ceiling to hide them. That is not the case with my situation.
220.127.116.11.4 states 18.104.22.168.1.1 shall not apply if ..
(B)* distance between the upper ceiling and deflector is less than or equal to 36 in. - in this case 18" so am I looking at a concealed spaces situation and can avoid sprinklers above ceiling plane if unobstructed or obstructed construction criteria are satisfied. We will have cable trays and ducts above the ceiling.
long winded question but thanks in advance for any feedback.