Plastering and skimming are two different techniques for finishing walls. Plastering involves applying a thick layer of a plaster mixture—typically containing gypsum, lime, cement, sand, and water—to create a new surface. This process often requires multiple coats and is used for repairing significant damage or creating decorative textures. Skimming, on the other hand, is a technique that involves applying a thin layer of drywall compound or joint compound over an existing surface to smooth it out, covering minor imperfections, small cracks, or uneven textures for a polished look. Plastering is generally more costly and labor-intensive than skimming. Although some people use the terms interchangeably, they refer to different processes and materials.

All plaster walls will crack over time due to normal house settling and expansion and contraction from temperature and moisture changes. Small, thin hairline cracks are generally not serious and are mostly a cosmetic issue. However, larger or more significant cracks can indicate structural problems.

Here's how to tell the difference:

• Cosmetic Cracks: Cracks that are 0.5 cm (0.2 inches) or thinner are typically cosmetic.

• Structural Cracks: Cracks wider than 0.5 cm, excessive or deep cracks, multiple cracks in the same area, or cracks that span around corners can signify a structural or foundation issue. Cracks along the joints where walls meet the ceiling also warrant attention.

For cracks wider than 0.5 cm, structural repair is needed. If a crack is 2.5 cm (1 inch) or wider, or if you notice any signs of a structural problem, it is best to contact a plaster repair professional to assess the damage.

Yes, it is possible to rewire a house without removing the drywall, but this doesn’t work in all homes. You can pull out old wires and insert new ones if you have access to the wiring system via the ceiling or through a crawl space. Some pros can also use a magnetic kit to fish the old wire out of the wall through a hole cavity and install the new wires. Just keep in mind that doing this is less stable than removing drywall, as you won’t be able to staple the wires into the framing.

In most cases, no, you won’t need a permit to replace drywall. If you’re changing the floorplan of your home by adding or removing walls during the drywall project, then you might need a permit, but replacement or repairs usually doesn’t require a permit. Your drywall professional should be able to confirm whether or not a permit is required for your project. If it is, it’s likely to add between $50 and $150 to your total cost. Keep in mind that you will need permits if you plan to install new electrical wiring or plumbing lines behind your new drywall.