Creating a furr in wire lath prior to self-furred wire was done with a furring wad. A round build up of layers of paper approximately 3/8″ thick stuck to the tip of a nail. The wad was nestled in the crotch of the wire touching at least three wires. When the nail head was driven home, it would compress the wad sealing the penetration of the attachment and kicking the wire out a minimum 1/4″. This process, when used with 16 then 17 gauge and also 20 gauge woven wire, allowed a scratch coat to bed the wire and attach the initial coat of plaster to a wall. Now we use self-furring wire like the v-grooved wire shown here.
The problems generally seen in the field are mostly application issues. Usually overnailing the wire and stretching it too tight. A tight wire means no amount of pressure applied by the plasterer to bed the wire with plaster can occur. I’ve seen one-coat plaster jobs where the wire was so tight when I tapped a plaster edge with a screwdriver handle a chunk of the wall fell off. There was no bedding, just a thin coat of plaster coating the top half of wire over foam.
The picture defines the measurement from the front of the paper (or structural underlayment) to the bottom of the lath. The measurement should be 1/4″.
One way of testing woven wire fitness is to grab the wire with your pinkie finger, if you can pull it out you can get plaster behind it and bed the lath. The other way of testing the furr is with a pencil eraser, which is exactly 1/4″ tall. Press the eraser against the wall, see where the wire sits, it should match the eraser housing. Voila, you’re good.
If you have questions about this condition or other situations, call or email:
Bell Construction Consulting
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