Archive through May 05, 2011

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Author Message Chris Grimm, CSI, CCS, SCIP Affiliate, LEED-AP, MAI, RLA Senior Member Username: tsugaguy Post Number: 258 Registered: 06-2005 Posted on Wednesday, May 04, 2011 - 01:55 pm:    Does anyone know of an exterior sheathing-like product that can take on a 3' radius for a dormer-like louver enclosure that has a curved top? The architect had initially said they were using glass-mat gyp sheathing as their "Exterior Board" when talking about some infill of openings, but I doubt we can bend it like that for on top of these dormers. I'm beginning to picture something like a semi-customized version of a GFRG column cover turned on its side now... Desired finish is stucco over metal lath. I'm having doubts about stucco too, being effectively horizontal at the top of these dormers. Lynn Javoroski CSI CCS LEED® AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1247 Registered: 07-2002 Posted on Wednesday, May 04, 2011 - 01:59 pm:    Could the sheathing panels be kerfed? Agree with your doubts about stucco... Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 947 Registered: 03-2003 Posted on Wednesday, May 04, 2011 - 02:03 pm:    If construction type will allow it, how about treated plywood with Bituthene or Vycor over the surface, then apply the stucco. We've done this with parapet walls using stucco over the top of the parapet. Ron Geren, AIA, CSI, CCS, CCCA, SCIP www.specsandcodes.com Chris Grimm, CSI, CCS, SCIP Affiliate, LEED-AP, MAI, RLA Senior Member Username: tsugaguy Post Number: 259 Registered: 06-2005 Posted on Wednesday, May 04, 2011 - 02:16 pm:    Waiting for mfr reps to call back on the kerfing but I think it would be to the extreme, to get the 3' radius. Would that be lauan plywood, to curve that tightly? I like the waterproofing idea over the top. Gerard Sanchis Senior Member Username: gerard_sanchis Post Number: 23 Registered: 10-2009 Posted on Wednesday, May 04, 2011 - 02:18 pm:    Listen, if stucco is that good, we ought to use it as a roofing membrane. All jokes aside, I wouldn't use plaster as a dormer roof, which is what the owner wants. Sheet metal is the conventional choice and no one is going to take you to court for selecting it – they might if you use plaster and it leaks (which it probably would). You can always paint the sheet metal with a heavy bodied acrylic paint with aggregates added for texture so it mimics a plaster finish coat. GFRC over a self-healing membrane might work as long as you keep the attachment points to a minimum. If you use a membrane under a sheet metal roof, which you should, you probably should specify a high temperature type (Grace Vycor or Ultra). Wayne Yancey Senior Member Username: wayne_yancey Post Number: 452 Registered: 01-2008 Posted on Wednesday, May 04, 2011 - 02:24 pm:    Sounds like an "eye-brow" louver in a roof. Support framing should slope to drain at top of radius. Space 2 x rafters close together. Grace Ultra over plywood roof sheathing. Check http://www.sbebuilders.com/eyebrow/index.php and http://northwoodsbuildersllc.com/new/new-Pages/Image15.html Dave Metzger Senior Member Username: davemetzger Post Number: 393 Registered: 07-2001 Posted on Wednesday, May 04, 2011 - 03:25 pm:    If plywood won't work (whether because of code or labor to kerf and bend it), consider 1/8" aluminum sheet or ACM such as Alucobond--won't have oil-canning issues as you would with thin sheet metal, and you'l get a more uniform radius than with plywood. If a stucco finish is still desired, I'd still use a high-temperature membrane over it, to provide self-sealing for screws supporting the metal lath. J. Peter Jordan (Unregistered Guest) Unregistered guest Posted on Wednesday, May 04, 2011 - 03:07 pm:    For a really tight radius, you could make it up in thiner layers of marine plywood (like 1/4-0or 3/8-inch); more expensive, but you would get the radius you want. One architect I know coats the near horizontal surfaces of EIFS or stucco with one or two coats of an elastomeric coating (not just the EIFS finish coat). I would prefer to see the sheet metal approach. You may be able to purchase these as fabricated items from someone like Campbellville Ind. John Hunter Senior Member Username: johnhunter Post Number: 87 Registered: 12-2005 Posted on Wednesday, May 04, 2011 - 07:39 pm:    I've had to do similar constructs for Orthodox Churches, look at Edon Fiberglass: http://www.edon.com/ and they may be able to provide a fiberglass fabrication that is waterproof and will provide the aesthetic you need. Steve Taylor Senior Member Username: steveatwi Post Number: 36 Registered: 07-2008 Posted on Thursday, May 05, 2011 - 01:29 pm:    Curved plywood can be made to just about any radius. In this case it should be built up of layers of 1/8" or 1/4" exterior grade ply. For a rough approximation of your 3 foot radius it could be built up on the job. For a nice smooth bend with an accurate radius it should be laminated in the shop.