dox plank

huangyhg

dox plank
does anyone know if there are published tables for the allowable load capacity of dox plank?  (looks like stack bond masonry spanning horizontally from underside of plank).  i looked at an existing roof of an old laundromat yesterday with 16" wide dox plank spanning about 24 feet.  the owner wants to cuts some small openings and possibly add some small mechanical units on the roof.
i know little more than that dox was a proprietary system used in inexpensive buildings requiring fire resistance and noise deadening between units, like in a motel.  
looking back on revisions made to building code and that so many structures from the 60's (the dox era) are not code compliant by today's standards (especially in areas with snow and drifting), i doubt you'll be able to safely reduce section or increase load.
however, if someone has some information out there on dox, i would like to learn more about it also.
good luck.
what little i know, i will pass along.  dox plank where made as you describe, from dox block placed end to end, with rebar threaded through and grouted solid.  hence, the 16" wide plank.  the reinforcing was 40 ksi mild steel.  they were one of the early floor and roof systems that evolved into the prestressed slab industry we see today.
the few times i've seen the system i have called my local prestressed slab supplier for information.  they didn't make dox plank, but it was one of there competitors back in the days before prestressed concrete.  you might try firms  like spancrete, flexicore or fabcon, some of their oldtimers might have some information on it.
i have a 1960 doxplank manual which includes original spec and allowable loading info.  let me know if you want something: