Re: rebar vs. wire mesh

Most metal building manufacturers povide a slab plan. Otherwise, you will generally need to have an engineer provide a design that considers, among other things, wind and snow loads, use of the building ,and soil type.

Light weight (6x6 10/10) wire mesh is freaquently used for light loading to provide temperature reinforcing. To get any kind of structural reinforcing will require bars. Your points of greatest concern (and loading) are going to be at the columnns.

Re: rebar vs. wire mesh

Make sure you pull the wire mesh up into the center of the concrete slab during the placement of the concrete. If you don't pull it up into the center, its not doing any good.

Unfortunately it is very common for the contractor not to do this. And as an inspector I see it sitting on the ground too often unless I say something to the contractor.

Re: rebar vs. wire mesh

wire mesh and rebar are really two different products that deal with concrete reinforcement with two different purposed.

Wire mesh is designed for nonstructal cracking due to shrinkage cracking and isolated vibration cracking due to movement on slabs ( people and equipment movement)

rebar is design for tension cracking due to structual loads applied to slab( weight of bldg and equipment) concrete will hold compression strength very good but the offset of this is the tension on the backside of the slab or bottom. As the load is applied the ends tried to curl like pushing down on a center of a book,the ends will curl up. Rebar is placed on the bottom to counteract this force. Rebar itself will bend inthe middle sideways but will hold a load in tension. so the weight applied on top of the slab is held by rebar in tension on bottom.

so a typical slab will have both. since there is no weight in center of area slab it is possible that no mesh is needed. Thats why some slab with wire on bottom as no effect on cracking. But it is better to have mesh in center of thickness of slab.

At this time I am building my house which will not have wire mesh. I,m using fiber instead. another subject thought.

but to answer your question: Two # 5 on edge in bottom of footing, wire mesh in area of slab.

Re: rebar vs. wire mesh

A well designed slab will use both rebar and wire mesh, if your building is a typical metal building. The slab will likely do double duty or be connected to the column footings. The mfg may supply a design for the slab/footings but more often they will just supply the column reactions. The slab will need to be engineered by someone. In high wind areas like the east coast, the slab and footing will need to resist overturning. Almost always in these areas, you will need to add more concrete just to weight down the building. Wire mesh is used when no other steel is needed. Fibermesh can be a problem if it doesn't get mixed well resulting in cracking.

glenn

Butler mfg. has a slab design manual that may assist you in doing your own design if your building inspector doesn't require an engineer.

A slab can be engineered for as little as $200.
This is money well spent.

Glenn

Re: rebar vs. wire mesh

>>Make sure you pull the wire mesh up into the center of the concrete slab during the placement of the concrete

Doesn't this apply to rebar as well?

>>Rebar is placed on the bottom to counteract this force.

Isn't it far more effective in the middle? Putting it on the bottom is most effective if the middle of the slab shrinks and the ends rise, but I have seen the opposite occur.

--ricka