Dens Glass Gold as Exterior Sheathing

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Author Message Robin Treston Unregistered guest Posted on Saturday, September 28, 2002 - 12:42 pm:    I have been specifying dens-glass gold as an exterior sheathing product under adhered stone tile veneer. Today, a product rep (fairly reliable) informed me that the DG product is not suitable for this application and I should use an exterior cement backer board. The DG website says the product is suitable for stone veneer. Has anyone else come across this? What do you use for exterior sheathing for adhered stone? Thanks! Richard Hird Unregistered guest Posted on Saturday, September 28, 2002 - 10:06 pm:    Dens glass is just faced gypsum board. Over the long run you have to anticipate that the gypsum board could get wet and deteriorate. This is not a problem if the veneer is mechanically fastened to the back up framing, but to "adhere a tile" it better not be over some ones head. Cement board is excellent for exterior surfaces. Have used it with success, even on soffits with a heavy finish coat. The only disadvantage is that its increased weight makes it more difficult to install. Also it can not be bent so you have to use cement stucco base coat on metal lath for curves. John Regener, AIA, CCS, CCCA, CSI New member Username: John_regener Post Number: 24 Registered: 04-2002 Posted on Saturday, September 28, 2002 - 11:06 pm:    See National Gypsum Company website for PermaBase Flex® cement board. It can be bent to a 6-inch minimum radius according to National Gypsum. William C. Pegues, FCSI, CCS Intermediate Member Username: Wpegues Post Number: 135 Registered: 10-2002 Posted on Saturday, April 05, 2003 - 03:08 pm:    Just browsing the threads here on this and noticed this topic. Dens Glass Gold is not just glass faced gypsum board. The gypsum particles are treated so that they do not absorb water. It will NOT saturate - you can take a piece of it and submerge it in water for some time and it comes out totally unharmed, cut it and its dry. Dens Glass Gold is the only exterior sheating product that I am aware of that if you specify that the joints are taped, they will guarantee the sheathing for up to 9 months I think of exterior exposure with the sheathing unprotected in even a coastal location should their be some delay in the finish products being delivered. A couple years ago, there was quite a delivery lag on some bricks, Ariscraft and some special finished CMU products here on the east coast and that became quite a problem - the building having to stand with the sheathing exposed for several months. On the other hand, though cement board is not bothered by the water, it does saturate and hold the water. That means that it does not dry out easily and whether it is from exposure, or just water migration in the wall, holding water in it is like a rigid sponge, and staying damp can harbor the growth of molds. Though if done correctly with a good adhered air barrier product it can be an excellent product with no problems. But I would put Dens Glass Gold as a superior product to a cement board for exterior sheathing. As noted, it is much lighter than a cement board, excludes water, is not harmed by water and does not deteriorate with exposure. William John Regener, AIA, CCS, CCCA, CSI New member Username: John_regener Post Number: 81 Registered: 04-2002 Posted on Saturday, April 05, 2003 - 07:53 pm:    I think the issue is the same problem that caused a big dispute between USG and Dryvit about EIFS ripping off of buildings under very high wind conditions. USG issued a notice that their gypsum sheathing product was not designed to carry the load of adhered products and should not be used as a base for EIFS or tile/brick/stone. There was failure not in the bond between the adhered product (expanded polystyrene board in the EIFS case) and the gypsum sheathing, but between the paper facing and the gypsum core of the gypsum sheathing. Find out from G-P and others manufacturers what loads their products will take from applied products (and also the negative wind load at corners of high rise buildings that lead to the EIFS failures). I think if there is concern about gypsum-base products deteriorating, then use a cement board where the product in homogeneous. But I agree with William, Dens-Glass Gold is an excellent sheathing material and the one I specify typically under EIFS. When I specify exterior tile or thin, mortar-set stone veneer, I do so over a lath and plaster setting bed so that there is mechanical attachment to the structure through the metal lath. William C. Pegues, FCSI, CCS Advanced Member Username: Wpegues Post Number: 136 Registered: 10-2002 Posted on Saturday, April 05, 2003 - 11:59 pm:    I specify a mechanically fastened extruded board for EIFS (when I have to use it) to avoid the glue on problem and load issues. Afterall, glue does not last forever just like sealants don't last forever. I mentioned that to an EIFS manufacturer's rep that was pressing hard to permit a substitution for the adhered system on a project. He replied, "How many failures have you seen due to age and failure of the glue." I replied that I had no knowledge of any such failures and that it was likely it would be very hard to document since after the glue fails its the EIFS mesh wrap and face coat that holds it on, and he could not give me a warranty on the life span of the glue, or what to tell the owner to do after 15 years or so when this might be a problem. William Lynn Javoroski New member Username: Lynn_javoroski Post Number: 19 Registered: 07-2002 Posted on Sunday, April 06, 2003 - 04:22 pm:    I've recently heard of USG FIBEROCK® Sheathing Aqua-Tough, a "homogeneous gypsum board with cellulose fibers dispersed evenly throughout the thickness of the board" with other additives. It has a water-resistant core and a coating on both surfaces with diagonal depressions on back of the board to help disperse condensation (or water). I was forced to specify this as an alternative to Dens Glass Gold. So I did a little research on it. Seems to answer the problem. Richard Hird (Unregistered Guest) Unregistered guest Posted on Wednesday, April 09, 2003 - 09:08 am:    Response from G-P to Robin's original application. I assume stone would not be different than ceramic. "Are you referencing ceramic tiles? If so, our DGG product is not recommended for this type of exterior cladding." Dave Brewster G-P Technical Services kodiak jurkiewicz (Unregistered Guest) Unregistered guest Posted on Wednesday, April 09, 2003 - 01:09 pm:    Underlayment. Looking for a common tile underlayment board for my bar. I am going to use this for my finished surface, but can't find the board in light green. I know I've seen it. I can only find gray. Does any one know of this material and where I can get it.