huangyhg

cracks in sheetrock demising walls
i have a cmu building with dimensions of 180' (long) x 90' (short). the roof slopes parallel to the short dimension at 1/4:12. the roof is framed with joist girders parallel to the short dimension and joists. the tenant spaces within this building are separated by cracked "demising" walls spanning parallel to the short dimension and are constructed of 3-5/8" metal studs with gypsum board each side spanning from floor to roof deck. inspecting the connection of this wall to the underside of the roof deck, it appears that there is no slip (deflection) track at the top of the studs. what is the most interesting is each wall is cracked (there are 5)at the same location both sides(approximately 1/3 the distance (30') from the low end of the building)throughout the entire building. these cracks do not extend full height of the wall, but start approx. 5' from the floor and extend to the ceiling and are only 1/8" (max.)in width. there is no evidence of floor slab distress. this building is approximately 2 years old, and the cracks first appeared about 6 months ago. i would appreciate any opinions as to the cause of these cracks. the tenants (jeweler, ice cream parlor, hairdresser, formal weir rental)are quite nervous as this area is known for expansive clay. sorry for the long post, but i wanted to (hopefully) paint a clear picture
it appears that the lack of deflection track is the problem. i had a similar situation where no deflection track was used below demising walls below a storage mezzanine. there was no problem until the mezzanine was loaded. does the sheetrock actually extend to the underside of the deck?
lsmfse,
thank you for your response. the sheetrock extends to within about 6".

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