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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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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:   Edit PostDelete PostPrint Post

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.

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