Whether to repair or replace water-damaged plaster depends on the scale of the damage. For small, limited areas, you can often perform a repair yourself. If you choose to paint over small patches, ensure the surface is completely dry and apply a coat of antifungal primer first to prevent mold growth. However, simply painting or plastering over the damage is only a temporary solution that doesn't address the core problem. For more extensive or long-term damage, the plaster may be compromised, and there is a risk of mold. In these cases, it is recommended to remove the damaged section of plasterboard and replace it. You may consider hiring a professional for the repair, and it's worth noting that water damage is often covered by home insurance.

Whether you can reuse a drywall anchor depends on its type, material, and how it is removed. Plastic anchors, such as expansion or self-drilling types, are generally considered single-use because they are designed to expand and are likely to break or become deformed upon removal. Metal anchors, like toggle bolts, are more durable and can often be reused if they are not damaged during extraction. However, with toggle bolts, the toggle mechanism can fall inside the wall when the bolt is removed, making it difficult to retrieve. If an anchor is damaged or must be cut for removal, it cannot be reused regardless of its material.

This depends on how much plaster is applied and in how many layers, but a decent estimate is around 150 square feet. If you are applying only two coats on a small wall, there is a chance you may only need one or two gallons for the entire project. If you are plastering a large living room wall with high ceilings, using one of the more involved techniques–like Scagliola–that requires several coats, expect the project materials costs to add up quickly. 

Plaster walls typically last between 30 and 70 years, but depending on the quality of the materials and the moisture levels in the building, they can last for over 100 years. With expert application and consistent maintenance, plaster can even last for centuries. To extend its lifespan, it is important to have the plaster professionally installed, address any water damage promptly, and repair small cracks as they appear. Regular inspections by a professional can help identify and address concerning cracks before they become significant issues.