Plaster requires more steps to prepare than drywall and is more labor intensive to work with. It has a lot more flexibility of application than drywall, but is also more expensive. These differences are the reason why it costs more to have walls plastered than it does to install drywall.
The level of skill and amount of time required to plaster walls is the reason this process is more expensive. However, because of its flexibility, plaster is a still good choice for walls with curves or odd angles.
Plaster is an ancient material that is still used on some newly constructed walls in homes and buildings. The process of making plaster compound begins by mixing the material and putting it onto a wood lath secured to a frame. Skill is required to get the consistency right when mixing. Three coats of plaster material are typically applied to walls. After the first coat is applied, the plaster is scratched, dried and covered by two additional layers. Plastered walls often appear to be thicker than drywall due to the multiple layers.
Drywall material is easier to work than plaster and can be installed much more quickly, which is why it is the less-expensive option. However, a downside to using gypsum drywall is that it lacks the aesthetic charm of plaster and may sustain water or mold damage.