Unbonded deck mud reinforcement

[Tim P.]

Given these two options, which would be the better choice:

-2" "chicken wire".. you know the stuff.. maybe 24ga?
-1" WWM.. 16ga I believe

In my uninformed opinion I think the heavier gauge 1" would be the best choice but the 2" chicken wire seems to be the go to around here. But maybe I'm just overreacting.

From reading I know 2" WWM is the recommended choice, but it isn't readily available (thus I'm seeing chicken wire).

Mud would be 1-1/2" to 2" taper, 7/8 advantech over 1/2 ply over 2x8 12"OC. Span is about 8'. I know mesh should be in the center of the slab.

I have experience in concrete work but deck mud is not something I've dealt with regularly. Especially unbonded. Just want to make sure we get the best product given the materials available.

Thanks for the help,
Tim

[Peerless Tile]

How big an area you talking about?....Are you putting down lathe and 15lb.paper as well?

[Davy]

Tim, when you say unbonded, does that mean you aren't planning to staple down the wire? Just wondering because usually when we talk about bonded and unbonded mud, we're talking about it going over a concrete slab. At least that's what I remember.

[John Bridge]

Hi Tim,

The heavier wire is best. First lay tar paper or plastic sheeting over the Avantech, and staple it down 6 to 8 inches in both directions. Then dump your mud and start screeding.

[Tim P.]

See, I'm not even using the correct terms

This is something new to me. Most construction is slab on grade and we use a thinset slurry to bond the deck mud in the majority of cases.

Now we are going over wood, over a crawlspace.

Size is approximately 34" x 48". Min mud thickness will be 1-1/2" at the drain. Slope will be min. 1/4" per foot.

Congruent with John's recommendation there will be roofing felt over the advantech. When you say "staple it down" are you referring to the WWM or the felt?

Basically I am trying to work out the details before we get started. I have notes sheets that I include in the plan set for every trade, but this application is new to me.

It's easy to say "use this and that" but in reality I try to specify products I know are available. That way the inevitable "we can't find that" is answered on the spot as I know what products are available locally. Chicken wire just does not seem appropriate to me, but again this isn't my forte`. I've just seen light gauge reinforcing completely rusted through in concrete applications.

[John Bridge]

Hi Tim,

Yes, lay the moisture barrier, lay the wire, and staple the wire through the barrier into the Avantech. The moisture barrier (tar paper) is not intended as a waterproof layer. It's purpose it to keep the wood from prematurely sucking the moisture out of the mud. With an inch and a half of mud you could actually omit the staples, but the staples hold everything in place while you're crawling around on it.

I have done many floors of thicker mud over concrete using the same materials. I actually like floors that are floating instead of bonding the mud to the concrete, but I digress.

[Tim P.]

Thanks so much for your help, John. I will add notes accordingly

[Lou_MA]

John -

You say staple the wire into the Advantech, but that would be in reference to expanded metal lath, correct? Doesn't any welded wire have to be in the vertical center of the mud?

[Davy]

I think that's mainly on a floating floor over a slab where there are no staples. This is over wood so I'd staple it every 6-8 inches apart like JB said.

[cx]

Yes, Lou, that would be correct.

Tim, if you have vertical room for a minimum of 1 1/4" mud thickness and want an unbonded mud application your welded wire mesh would go in the vertical center of the mud.

The smallest wire mesh permitted by ANSI standards would be a 1 1/2x2" 16/13 gauge welded wire. Ain't no "chicken war" approved at all in that application.

You'll wanna be sure your structure can tolerate that extra weight, too. At the minimum thickness you're adding 21 psf.

My opinion; worth price charged.

[Davy]

They do make a heavy gauge wire made for plastering that looks like chicken wire. I have no idea of the gauge or if it's approved. I know we used many rolls of the stuff in California when mudding floors. It wasn't poultry wire.

[cx]

Davy, I think the tile guys organized in northern California do "approve" a chicken-wire looking material for use as mud reinforcement, but I've no idea just how it's identified. Been in committee discussions where that subject was introduced and them upper California guys think it's good and useful stuff.

I've also seen a similar product sold in my part of the country as stucco reinforcement. Very heavy chicken-wire that. No chickens gonna be getting through it even if they are very large chickens, such as emus.