Bar supports for galvanized metal deck / composite slab

[thoughtofthis]

Should Class 1 or 2 bar supports be used for galvanized metal deck / composite slabs? Class 3 bars seem inappropriate since the idea is to protect the steel. Also, if the deck is vented, the bottom surface is more exposed. From a cost standpoint, it seems like plastic chairs would be the cheapest option anyway.

 

[TXStructural]

You can use plastic, precast, plastic-tipped wire, or fully-coated wire supports with no problems. If you have moisture exposure, avoid a plain or coated metal support, which could set up a macrocell corrosion situation. You will probably want to avoid use of composite metal deck, galvanized or not, if the slab is exposed to moisture, since it will rust away over time (often less than 20 years.)