Field note
Type A lath screws for metal plaster base
Type A is the plaster-base screw. Coarse-pitch tapping thread for metal plaster base (lath) to wood or to cold-formed steel. It is not the interior gypsum bugle on a Level 4 corridor. If the wall-and-ceiling package includes metal lath, this is the class. If it does not, leave the box on the shelf.
This page restates public class language from ASTM C1002 (and C954 when the steel is too thick to pierce). Official fastener data — Grabber and peers — should match that class. Current sheets: grabberpro.com. Not a SKU catalog. Cluster: Fasteners. Steel members: steel stud framing basics.
What Type A is
C1002 lists four thread types. Type S, W, and G are gypsum-panel jobs. Type A is the remaining one: coarse-pitch tapping thread for fastening metal plaster bases to wood members or to cold-formed steel (still in the C1002 thickness range — less than 0.033 inch).
Metal plaster base is diamond mesh, self-furring lath, paper-backed lath, and the related sheets a plaster or stucco system hangs before the scratch coat. It is not gypsum wallboard. A bugle-head Type S or Type W will pull through mesh or sit wrong on a rib. Lath wants bearing: wafer, truss, or pan-style heads that clamp the metal without cutting it off the fastener. See drywall screw head types.
What it fastens. Metal lath to wood studs and to light-gauge steel that still takes a piercing point. Interior plaster, some exterior stucco backup when the system still uses a C1002-class screw, soffits, and the plaster package a commercial W&C shop still carries in some markets.
What it is not. Not a gypsum hang screw. Not a laminating screw. Not a cement-board tile-backer screw. Not automatically the right point once the steel hits 0.033 inch — that thickness moves gypsum and plaster-base screws into ASTM C954 drill points. See self-drilling framing screws.
Point and thickness
Same gate as Type S. Self-piercing Type A belongs on wood and on light-gauge steel. Heavier steel wants a drill point the plaster-base manufacturer and the fastener house name. Spinning on the flange is the field test you should not need: you brought the wrong point.
Wood lath screws still need thread into the member — penetration is a manufacturer and plaster-system note, not a drywall 5/8-inch habit copied onto mesh. Exterior and wet-area lath often want a corrosion-resistant coating the stucco or plaster manufacturer will accept. Interior drywall phosphate coating is the wrong assumption on an exterior scratch coat.
Self-furring dimples and furring nails are part of some lath systems. Type A does not replace a furring accessory the system drawing showed. Read the lath mill and the plaster spec; this page will not invent a stucco assembly.
Head, spacing, and plaster — not drywall finish
Lath screws are not dimpled for joint compound. The head has to hold metal, then disappear under plaster thickness the system named. Overdriving cuts wire. Underdriving leaves a lump the scratch coat will telegraph.
Spacing is the lath and plaster manufacturer’s table (and ASTM C1063 for lath application, where that is the specified document) — not C840’s gypsum screw table. Do not hang diamond mesh on 16-inch drywall centers because that is how the hang crew thinks. Edge distance, end laps, and corner reinforcement are lath rules.
Gypsum board hung over lath, or veneer plaster over gypsum, is a different system again. Veneer plaster on gypsum still uses gypsum fasteners (Type S / Type W) into framing. Type A is for metal plaster base, not for hanging drywall that will later get a veneer coat.
Commercial vs residential
Commercial wall and ceiling. Type A shows up when the shop still owns plaster, historic interiors, some soffits, parking-garage or stair plaster, and exterior stucco backup that stayed in the drywall number. Many commercial interiors never see it — they are gypsum and ACT. Do not put Type A on a gypsum hang takeoff “for extras.”
Residential production. Rare on a production house. Cement board and gypsum dominate wet rooms and interiors. Lath still appears on stucco exteriors, some high-end plaster, and repair. The production hang coil stays Type W. A stucco elevation is a different fastener and a different crew mix.
Keep the pouches apart on a mixed job: gypsum hang, lath, metal-to-metal framing, cement board. Four languages. Four boxes.
What to put on the takeoff
Name Type A (C1002) or the C954 drill-point plaster-base class, head style (wafer / truss / pan), coating for interior vs exterior, and the lath mill’s spacing. Point at the plaster or stucco spec section, not at the drywall hang guide, for pattern.
Official data: Grabber, grabberpro.com. Directory: Fasteners, Tools. Products: Products. Gypsum hang on the same floor: how to hang drywall. No ASINs, no affiliate URLs, no item numbers. Affiliate disclosure.
FAQ
Can I hang metal lath with Type S bugle screws?
Bugle heads are the wrong bearing for mesh. Use the lath-class head (wafer / truss / pan) the mill names. Thread type is Type A, not a gypsum hang leftover.
Is Type A a drywall screw?
No. C1002 includes it because plaster base is in the same fastener specification family. The job is metal lath, not gypsum.
When do I need a drill point?
When the steel is 0.033 inch and thicker — C954 territory — same thickness gate as gypsum into heavy steel.
Does C840 spacing apply?
C840 is gypsum application. Lath spacing is the lath / plaster document (often C1063) and the mill sheet.
Where do we buy them?
Fastener house and the plaster supplier. Official sheets: grabberpro.com. Manufacturer listings stay editorial.