Subject: RE: Unit weight of precast roof plank from 1960
From: "Sprague, Harold O." <SpragueHO(--nospam--at)bv.com>
Date: Fri, 2 Jun 2000 17:42:26 -0500
Back in the old days there were several products used that were referred to
as structural roof materials such as:
Cement Roofing Tile
Thermo Slab Tile
Federal Cement Tile
United States Gypsum made several products
Zonoloite Concrete Roof Deck
Celotex Cemesto Roof Deck
If it is called out as a 3" Precast Roof Plank, I would guess it to be a USG
product which would have a DL of 17 psf or the 3" Zonolite is listed at 15
psf. I would check the density to be sure.
Many of these products contained asbestos. I would have it tested.
> -----Original Message-----
> From: mark swingle [SMTP:mswingle(--nospam--at)souzatrue.com]
> Sent: Friday, June 02, 2000 3:44 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Unit weight of precast roof plank from 1960
> We are investigating an existing building in Massachusetts, built in 1959
> and 1964, to which an addition is currently being attached. It is a
> one-story building which framing consists of open-web joists at 4' oc
> supported by steel beams and columns on spread and strip footings.
> Exterior walls are CMU infill.
> The existing drawings call out <3" PRECAST ROOF PLANK> spanning the 4 ft
> between joists. Does anyone know the unit weight of this material?
> Breyer's 3rd edition lists <concrete plank> at 6.5 psf per inch, which is
> 78 pcf. Regular-weight concrete is 145 pcf.
> Is Breyer correct? Is this the same thing? In other words, was
> light-weight concrete in use for roof planks in 1959 and 1964?
> By the way, if I use 145 pcf, some of the existing joists and beams are
> overstressed, which seems unlikely.
> Any history lessons from you old-timers will be greatly appreciated.
> Mark Swingle, PE, SE