Installing curtain hardware on plaster walls is a challenging project that can easily go awry. Plaster is known to break and damage large portions of your wall. This can also cause your curtain rod to fall out and become damaged as well. The trick to preventing this from happening is to correctly install the curtain hardware into the wall.
Step 1 - Mark Rod Placement
Hold up your curtain rod where you want to install it, and use the level to make sure it is even. It may be easier to have a helper for this step. If you are by yourself, use a few pieces of electrical tape to secure the level to the top of the curtain rod; this is much less awkward than trying to control both with one hand. Make a pencil mark where the bolts will go into the wall.
Using the utility knife, make two small cuts in the shape of a cross over each pencil mark for the bolts. The cuts do not have to be long or deep. The cuts should only get through the plaster surface.
Step 2 - Nail and Drill Through Cross-Cuts
Carefully start to drive the tip of a nail through the center of each cross cut. You should hammer these gently; just enough to start a hole through the plaster. Make sure not to hammer too hard because the surrounding plaster can easily crack.
First look up the size of the recommended drill bit on the specifications that came with your lag bolt. The size of the drill bit should match the size of the bolt's flat lag and not just the bolt itself. The flat lag is a small anchor that can be adjusted to form a T shape with the lag bolt. Using the drill bit, drill through the holes in the plaster you started with the nails. It is best to use the slowest setting on your cordless drill for this step.
Step 3 - Install Lag Bolt
Your standard lag bolt has three parts: the lag, the shielding system, and the bolt itself. Hold the lag bolt so that the lag coming off the bolt is in a straight line. Also make sure the shielding sleeve is flush with the bolt head. Holding the lag bolt in this position, push it into the holes you drilled. You should feel the lag part come free inside the wall. Next, hammer the head of the bolt lightly until the shielding sleeve is firmly in place against the wall.
Fit your box wrench around the top of the lag bolt and tighten it until you feel the lag press firmly into the plaster. Repeat this process on both sides of where you will install the curtain rod.