From: Robert Kazanjy <rkazanjy(--nospam--at)gmail.com>
Date: Fri, 8 Apr 2005 21:14:47 -0700
I see if I can dig up some data on a large roof diaphragm; spaced 1x4
or 1x6 sheathing
( I cannot rmember the detail right now)
We tested for shear resistance before the shingles went on. This
might will you a lower bound number.
Your client can't have it both ways.
Maybe the "right" solution is remove the T&G, sheath & replace the T&G.
Also if it's his hobby farm why the galv screws?
Use SS, the cost increase is minimal compared to the boost in performance.
The addition of 15 gage fiinish nails (lots of them) might be a
On Apr 8, 2005 12:05 PM, Rhkratzse(--nospam--at)aol.com <Rhkratzse(--nospam--at)aol.com> wrote:
> CORRECTION OF TYPO IN THIRD PARAGRAPH! Sorry.
> Having grown up in rural Pennsylvania I always thought barns were supposed
> to be a bit swaybacked and leaning--that added to their appeal. Well, maybe
> not if it's a "recreation building."
> Since timber barns often had diagonal sway bracing, perhaps you could
> retrofit either sway bracing or larger diagonal braces within the existing
> timber wall frames to provide lateral strength. Certainly either would be
> more in tune with the aesthetic of a barn than would steel straps all over
> the place.
> In any case I would *not* count on the moment couple of pairs of screws in
> 4" wide boards to brace such a building. A few months or years, or one
> significant STORM, is likely to knock the building down *again*.
> Maybe if this were a real agricultural buildling full of hay to cushion the
> blow (of collapse) that might be acceptable, but what would the owner say if
> the building collapsed on his family?
> Ralph Hueston Kratz, S.E.
> Richmond CA USA
> In a message dated 4/8/05 9:29:46 AM, mollyhamann(--nospam--at)hotmail.com writes:
> Does anyone have any information about the strength of vertical tongue and
> groove cedar siding acting as a diaphragm? He is the situation:
> I have been asked by a building contractor to determine if a barn which is
> already built needs additional lateral bracing. This barn was originally
> designed by an engineer; however, there was no detail for diagonal bracing,
> or a plywood diaphragm. I understand the original engineer thought they were
> installing a plywood diaphragm, however, after some design modifications,
> this detail did not end up on the final drawings. The contractor wants to
> know if it is necessary to install diagonal bracing at this point, or if the
> siding provides adequate shear strength. The wall studs are 2x8 at 16" oc,
> with a 14' wall height. 2x4 purlins are attached to the outside of the studs
> at 24" oc. Cedar tongue and groove siding (7/8") is attached to each purlin
> with 2-#9 galvanized screws per panel. The panel width ranges from 4" to 8".
> The footprint of the barn is 36'x56' with various openings for windows and
> Additional background information: This barn is a 2 level bank barn, with
> the first floor being poured concrete walls with a stone finish, and the
> second floor a timber frame. The second floor will probably be used as a
> recreation area. This barn is for a "hobby farm" and the owner prefers the
> way it looks with the inside unfinished. He does not want to drywall or
> finish the inside. Last winter, this barn was erected and the contractor was
> in the process of installing the roofing, when some temporary wall bracing
> was removed which resulted in the barn blowing over during a storm. There
> was no siding installed when the barn blew over. After this, the contractor
> began to question the lateral bracing of the finished structure. The
> contractor rebuilt the barn, and then went back to the engineer for a
> bracing plan. The original engineer provided a post-construction bracing
> plan, which amounted to diagonal 〓" x 3' steel straps tied to the inside of
> the wall. The owner is not looking forward to installing these straps to the
> inside of the wall for aesthetic reasons.
> Coming up with an alternate lateral bracing system which does not require a
> major construction effort at this point (after construction) may be
> challenging. I was wondering if anyone had any information about the
> strength of vertical cedar siding as a diaphragm. I talked to a
> representative of Western Red Cedar Lumber Association, but the only
> information I got was this: If Cedar Siding is used without a plywood
> diaphragm, and applied to outside purlins, it is recommended that the siding
> be attached to purlins spaced at 16" o.c. Unfortunately, the as-built purlin
> spacing is 24"o.c. Additional, this barn must be designed to the
> requirements of IBC 2003.
> I would appreciate any comments or advise on this subject.
> With regards,
> Molly H. Hughes
> Ralph Hueston Kratz
> Fax 510-215-2430
> 724 McLaughlin Street
> Richmond CA 94805-1402 USA
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