[Strawbale] Mesh Mish-mash (was Re: 2x2" galvanized welded wire mesh for SB house

[Rob Tom]

Andrew Morrison <Andrew at StrawBale.com> wrote:

> The problem is that the "wwm"stands for WOVEN wire mesh, not WELDED wire  
> mesh. The woven wire mesh has absolutely no shear value.

> Tenax is a great product to use; however, it does not offer much shear
> strength.

> I have enjoyed using the Hardy Frames as they supply a great deal
> of shear value


In-plane shear resistance for SB walls is about providing tensile  
resistance.

Using 2x2 welded wire mesh to provide that shear resistance is like  
driving an SUV to the suburban corner store for a bag of milk.

Yes, it sort of does the job but , well, you know.

The fact is, even wimpy 22 gauge chicken wire, when installed properly (ie  
pre-tensioned) can provide all the tensile resistance that is necessary to  
deal with both in-plane and out-of-plane live loads in most load-bearing  
residential SB construction. (See the mid-1990's CMHC report "Development  
and Proof-testing the "Pre-stressed Nebraska" Method For Improved  
Production of Baled Fibre Housing".

Plastic meshes like the Tenax lines are even stronger than the chicken  
wire that was used in the above. And unlike wire meshes, plastic meshes  
will never rust.

Of course, meshes like chicken wire or the plastic meshes will seem  
"flimsy" as compared to 2x2 welded wire mesh but as mentioned, shear  
resistance is about providing tensile resistance. ie A "flimsy" small  
diameter nylon rope or polyester rope can be used to pull an incredibly  
heavy load.

And yes, of course if you apply a lot of force to a single strand of a  
light gauge mesh, it will break a lot easier than would a strand of a  
heavier gauge mesh. But that's a problem with the person doing the yanking  
rather than shortcomings WRT the mesh.
The person doing the yanking should know to distribute the force over a  
larger number of the strands.

A pretty good argument can be made for using lighter meshes comprised of  
smaller strands and smaller grid sizes since the loads will be distributed  
more evenly over a given span.

What this means is that the stresses at each point of attachment (ie to  
the plates) will be lower and hence, less prone to failure where "failure"  
is more likely to be that of the wood or the fastener rather than the mesh.

-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at chaffY a h o o  dot  c a >
manually winnow the chaff from my edress in your reply