How to Screw Into Plaster Walls | Without Cracking Them

Screwing into plaster goes sideways fast. One over-eager turn of the drill and you’ve got a crater, crumbling dust, and a hole that won’t hold anything. Whether for a small picture frame or a heavier mirror, the process is simple if you follow the right order. Skip the anchor or use the wrong bit, and you’ll be patching by dinner. Here’s the method that works.

What You Need To Know Before Drilling

The most important step happens before picking up a drill: figure out what’s behind the plaster. Most older homes have plaster over wood lath strips, while newer builds may have plaster over drywall or directly against studs. That difference changes everything about how you fasten.

For light items under five pounds, a screw can sometimes hold in plaster alone, but that’s the exception. Best practice is to find a stud or use a plastic anchor, toggle bolt, or molly bolt sized to what you’re hanging. IKEA’s wall anchoring guide stresses the same rule: match the screw and anchor type to both the wall material and the object’s weight.

How To Screw Into Plaster Walls: The Step-By-Step

1. Mark the spot and cover it with painter’s tape. Use a pencil and level for placement, then press tape over the mark. The tape keeps plaster from chipping at the edges while drilling.
2. Choose the right bit for your anchor. The bit should match the anchor’s diameter — about the same size or just slightly larger for a snug fit. A 1 1/4-inch drywall screw works for lighter items; step up to 2-inch screws when you need more bite into a stud or lath.
3. Drill slowly with light pressure. Keep the drill perpendicular to the wall and run it at low speed. Fast drilling generates heat and vibration, which cracks plaster. Clear dust by pulling the bit out occasionally.
4. Feel for the transition. If you hit wood lath or a stud, the drill will suddenly resist more — a screw can grab there directly. If you pass into hollow space, you need an anchor.
5. Insert the anchor flush with the wall. Tap it in gently with a hammer if needed. The flange should sit level — not sunk in, not sticking out.
6. Drive the screw until snug, then stop. Overtightening is a classic mistake. Once the head meets the anchor and the item is secure, quit turning. Going further strips the anchor or crushes the plaster.

When done, the screw should feel solid — no wiggle, no spinning. If it turns freely or pulls out, you’ve got the wrong size anchor or a hole that’s too big; remove and replace the hardware.

Choosing The Right Anchor For The Load

Not all anchors are equal. Plastic expansion anchors handle light to medium loads up to roughly 20-30 pounds when properly installed. Toggle bolts spread the load across a wider area and handle heavier items. Molly bolts — hollow-wall anchors — grip the plaster itself and sit flush, a solid middle ground.

For anything heavy like a large mirror, shelf bracket, or wall-mounted cabinet, skip the plastic anchor. Use a toggle or molly bolt with a rated capacity matching the item’s weight, or better yet, aim for a stud. The Craftsman Blog and Lifehacker both recommend 2-inch screws for heavier items because the extra length lets threads reach the wood lath or stud behind the plaster.

For a quick reference on which fastener handles what, our tested roundup of the best fasteners for plaster walls covers the hardware that actually holds up.

Common Mistakes That Ruin Plaster Walls

Most damage comes from a few repeatable errors. Drilling too fast or pushing too hard is the top cause of cracking. A bit too small forces the anchor in and cracks the plaster; a bit too large leaves the anchor loose. Overtightening deepens the anchor or strips the hole.

There’s also the stud finder problem. Generic electronic finders often give false readings on plaster-and-lath walls because lath strips and plaster create confusing density changes. Some guides recommend locating lath nails with a magnet or tapping the wall to hear hollow bays versus solid studs instead of trusting a finder not built for this wall type.

If the screw spins or won’t bite, the fix is straightforward: back it out, install an anchor sized to the drilled hole, and drive the screw again. A hole already too large won’t hold — patch it and start over in a new spot.