Patching and Plastering - Plaster / Metal Lath Questions

HI;

My plastering projects are progressing well, the kitchen is almost all patched up, new sofit boxes built and am working on the plastering now. I just covered all the old plaster with a bonding agent.

When I use metal lath, does it matter at all what the substrate is under the lath or if there even is one? For example if I have a hole I need to patch, can I just secure metal lath to the back side of it and plaster it? I did this in one spot and it seems to have worked, but I am not sure if it is a correct use of lath or not. How frequently does metal lath need support, can it just be attached 16" o.c.?

Thanks very much,
Jamie

The short answer is yes metal lath can be used without backing. That is it's intention. In fact if you have backing you should use self furred metal lath. it has 1/4" dimples every 4" every direction to hold it away from the substrate so some material can get behind it.
If there is something to attach it to you can use it without backing

Stucco Resources Stucco Materials Stucco Technology | Stucco Guru - Resources (http://www.stuccoguru.com/resources/resources.cfm?resourceID=3)

THE DEADLY SINS: EXPANDED METAL LATH INSTALLATION FOR THE APPLICATION OF PORTLAND CEMENT PLASTER (PART II) (http://www.stuccoguru.com/resources/article.cfm?articleID=B-01050&resourceID=3)

This is supposed to be two different links. If they both take you to the same article you can navigate either to the first or second in the series as is appropriate.
This tell you almost everything you need to know about metal lath.

I think you told me you have gypsum plaster over gypsum lath. I've had good success screwing a piece of plywood or a 1 X 4 or a 1 X 2 to the back side of the gypsum lath such that is spans the hole and is screwed beside the hole by a few inches then cutting a piece of lath a little larger than the hole, screwing it to the wood and then trimming the lath to fit precisely. If there is something to tie to wire ties can also be used to help hold the lath. Remember that the lath holds the plaster not the other way around. Use screws with a big head so it holds the lath without it pulling right through. Make sure you bond the new plaster well to the edges of the opening.

If you have 16''OC joists you should use 3.4 lath I think but I don't remember for sure that you can use 2.5 lath on walls at 16"OC studs. For patching you mostly do what works.

The short answer is yes metal lath can be used without backing. That is it's intention. In fact if you have backing you should use self furred metal lath. it has 1/4" dimples every 4" every direction to hold it away from the substrate so some material can get behind it.
If there is something to attach it to you can use it without backing

Stucco Resources Stucco Materials Stucco Technology | Stucco Guru - Resources (http://www.stuccoguru.com/resources/resources.cfm?resourceID=3)

THE DEADLY SINS: EXPANDED METAL LATH INSTALLATION FOR THE APPLICATION OF PORTLAND CEMENT PLASTER (PART II) (http://www.stuccoguru.com/resources/article.cfm?articleID=B-01050&resourceID=3)

This is supposed to be two different links. If they both take you to the same article you can navigate either to the first or second in the series as is appropriate.
This tell you almost everything you need to know about metal lath.

I think you told me you have gypsum plaster over gypsum lath. I've had good success screwing a piece of plywood or a 1 X 4 or a 1 X 2 to the back side of the gypsum lath such that is spans the hole and is screwed beside the hole by a few inches then cutting a piece of lath a little larger than the hole, screwing it to the wood and then trimming the lath to fit precisely. If there is something to tie to wire ties can also be used to help hold the lath. Remember that the lath holds the plaster not the other way around. Use screws with a big head so it holds the lath without it pulling right through. Make sure you bond the new plaster well to the edges of the opening.

If you have 16''OC joists you should use 3.4 lath I think but I don't remember for sure that you can use 2.5 lath on walls at 16"OC studs. For patching you mostly do what works.

I just wanted to thank you for this information on metal lath.

Jamie

Hi, I found this thread after a lot of searching. I know it's pretty old, but is anyone still monitoring this? I need some answers in a big way. thanks,
jt

Welcome to the forums jt!

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