How To Drill Into Plaster

Drilling into plaster walls can be a challenging task, especially in older homes where plaster is thicker and more brittle than modern drywall. However, with the right techniques and tools, you can successfully hang pictures, shelves, and other items without damaging your walls. This guide will walk you through the process step-by-step, helping you avoid common pitfalls like cracking, crumbling, or creating messy holes in your plaster walls.

Materials and Tools You’ll Need

Before you begin, gather these essential items:
1. Electric drill
2. Masonry drill bits (various sizes)
3. Tape measure and pencil
4. Masking tape
5. Stud finder (preferably magnetic for old plaster walls)
6. Wall anchors appropriate for plaster
7. Vacuum or damp cloth for cleanup
8. Safety glasses and dust mask

Understanding Plaster Walls

Plaster walls, especially in homes built before 1950, consist of a hard plaster coating applied over wooden laths (thin strips of wood). Modern plaster walls may have metal lath or wire mesh instead. This structure is different from drywall and requires specific techniques for successful drilling.

Phase 1: Preparation

Step 1: Locate Wall Studs

For heavier items, drilling into studs provides the most secure mounting. For older plaster walls:
1. Use a magnetic stud finder to locate nails in the wooden laths, which indicate stud positions.
2. These are more effective than electronic stud finders on old plaster.
3. Mark stud locations with a pencil if you need to mount to them.

Step 2: Mark Your Drilling Point

1. Measure carefully and mark exactly where you want to drill.
2. For picture hanging, use a level to ensure proper alignment.

Step 3: Apply Masking Tape

1. Place a piece of masking tape over your marked drilling spot.
2. This helps prevent the plaster from cracking and gives your drill bit better grip.
3. Mark your drilling point again on the tape.

Phase 2: Drilling Technique

Step 1: Select the Right Drill Bit

1. For plaster walls, use masonry drill bits rather than standard wood bits.
2. Start with a smaller pilot bit (1/8″) before moving to larger sizes if needed.
3. Ensure your bits are sharp – dull bits create more friction and can damage plaster.

Step 2: Drilling the Pilot Hole

1. Set your drill to a slow speed setting.
2. Position the drill bit perpendicular to the wall.
3. **Important:** Apply very light pressure – let the drill do the work.
4. Start drilling slowly until you break through the hard plaster surface.
5. You’ll feel less resistance once you get through the plaster into the lath behind.

Step 3: Enlarging the Hole (If Necessary)

1. If you need a larger hole, switch to a slightly bigger bit.
2. Drill slowly through the existing pilot hole.
3. Continue this process until you reach the desired hole size.

Phase 3: Installing Anchors and Hardware

Step 1: Choose the Right Wall Anchor

1. For light items (under 10 pounds): plastic expansion anchors work well.
2. For medium items (10-25 pounds): use toggle bolts or molly bolts.
3. For heavy items (over 25 pounds): find a stud or use heavy-duty toggle anchors.

Step 2: Install the Anchor

1. Clear any dust from the hole using a vacuum or blow it out.
2. Insert the appropriate anchor following manufacturer’s instructions.
3. For toggle bolts, ensure the wings can open fully behind the plaster.

Step 3: Insert Screw or Hook

1. Place your screw or hook through your fixture and into the anchor.
2. Tighten carefully, avoiding over-tightening which can crack the plaster.

Tips for Success with Old Plaster Walls

– Take it slow: Rushing is the main cause of cracked plaster.
– **Use the TEK screw technique:** For very hard plaster, some professionals recommend using a #8 x 1/2″ HH TEK screw to penetrate the first 1/8″ of hardcoat before switching to your regular drill bit.
– Minimize pressure: Let the drill bit do the work rather than forcing it.
– Watch for dust color changes: White dust means you’re in plaster; brown dust means you’ve hit wooden lath.
– Consider pre-drilling: For very brittle plaster, you might drill a tiny 1/16″ hole first, then enlarge gradually.

Troubleshooting Common Issues

If the Plaster Starts to Crack:

1. Stop drilling immediately.
2. Try a new spot nearby, applying masking tape first.
3. Use a smaller bit and drill more slowly.

If the Drill Won’t Penetrate:

1. You may have hit a particularly hard section or possibly metal lath.
2. Try the TEK screw method mentioned above to break through the hard surface.
3. Consider moving to a different spot if possible.

If the Hole Gets Too Large:

1. Use a larger wall anchor than originally planned.
2. For significantly damaged areas, consider patching with plaster repair compound before trying again in a new spot.

Frequently Asked Questions

Why is my drill not penetrating the plaster wall?

Old plaster, especially in homes built before 1940, can be extremely hard. Make sure you’re using a masonry bit, not a standard wood bit. Try the TEK screw method to break through the initial hard layer, and ensure you’re using a drill with sufficient power.

How do I find studs in old plaster walls?

Magnetic stud finders work best on old plaster walls as they detect the nails used to secure the wooden laths to the studs. Electronic stud finders often struggle with the density and irregularity of plaster. Look for a pattern of nails every 16 or 24 inches.

Do I need special anchors for plaster walls?

Yes, standard drywall anchors often don’t work well in plaster. Toggle bolts and molly bolts are more effective for medium to heavy loads. For very light items, plastic expansion anchors can work if installed properly.

How do I repair a hole in plaster if I make a mistake?

Small holes can be filled with spackling compound. For larger holes or cracks, use a plaster repair patch kit that includes mesh tape and setting-type joint compound. For significant damage, you may need to consult a professional plasterer.

Can I use a hammer drill on plaster walls?

It’s generally not recommended to use a hammer drill on plaster as the hammering action can cause the plaster to crack. A standard drill with a masonry bit on a slow speed setting is the safer option.

By following these steps and tips, you can successfully drill into plaster walls without causing damage. Remember that patience is key – taking your time will result in cleaner holes and less repair work later.