Anonymous
Anonymous asked in Home & GardenDo It Yourself (DIY) · 1 decade ago

Plaster and drywall differences?

I've done drywall for about 7 years now off and on. I've been curious about plaster and how much it differs from finishing gypsum board (drywall). I saw some plasterers on "This Old House" show doing this and caught my attention. From what I've seen, the finishers coat the entire wall and hardly ever need sanding. Can anybody tell me whats involved in plastering? Do they tape joints, what is backing material, how many coats of what, and is it easier or harder to do than modern drywall techniques? Any cons of plaster?

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  • 1 decade ago
    Favorite Answer

    I see some valid answers here, and yes "plaster" is making a trendy "comeback"

    I personally wouldn't do it, nor even bid a job that meant more than patching, and I've installed thousands of sq. ft. of "drywall."

    The different qualities aside, one answer best defines my rationale. Cost and Labor intensity.

    I saw that same show, and understand this. It's TV, and shot sequentially but segmented. Beyond that I don't accuse the film editors of "cheating." The shows are usually not very long in each thing they show. A Decent, skilled, experienced plaster mechanic can very likely do what is shown, as can drywall hangers/tapers/mudders, install and finish drywall, using "Hot Mud" etc. allowing minimal sanding.

    Steven Wolf

    (The Rev.)

    Source(s): 40 plus years as a contractor
  • 1 decade ago

    I had a fire at my house a year ago and had to totally rebuild my house from the ground up. The old house was built in 1942 and what they did was use a 1/4 Inch Drywall, then did a 1/4 inch brown coat which looked like cement and then finished it off with 1/4 inch of plaster.

    The walls where super hard, and whenever we did any remodeling at the old house we literally had to take a saws all and a hammer to remove the plaster walls.

    When we did the new house, we where forced to do drywall and I hate it. Everytime you accidently bump it with a piece of furniture, it dents and then there are seveal places in the house where I noticed mistakes like nails poping out or where you can bairly notice a seem.

    Plaster is just not cost effective, and even if you wanted to spend the money to have it done the question is where do you find someone who is skilled enough to do it right

  • Anonymous
    1 decade ago

    My dad had an old house and he re-plastered the entire interior. A plasterer came and did it. He mixed plaster with lime and applied it to the walls which had what he called lath, which were rows and rows of thin pieces of wood . Now days they probably use drywall or perhaps some kind of wire netting. Anyway, he did the base coat and then a finish coat that was as smooth as glass. I was amazed by his skill. It has been thirty years and it still looks like he just applied it yesterday, except in the bathroom around the toilet area. Now days its hard to find those kind of highly skilled plasterers here in America. Ive heard that people will bring them over from Italy to do a big job. And yes, they do tape the joints.

  • 1 decade ago

    You already have some good answers, this is my two cents worth.

    The board that is now used as the base may look like sheetrock, but it is totally different. It is not at all just in the outside skin of the board, it is a totally different product. They no longer use wood lath as the base.

    Plaster is put on is several layers. Each layer if different. There are different numbers of layers and different materials in each, depending on the installer's methods.

    It is MUCH harder to do than drywall. It is MUCH stronger than drywall. It is more soundproof, longer lasting, etc. I think it looks and feels a lot better, too.

    When I did a project with it, I researched it in several books. Each said something different. I then went to a local, high end, building materials supplier and got the materials. They also had an old guy who gave me some tips.

    It was a lot of work, but I think it was worth the extra work since it was my house. I would do it again, the same way, but it was a LOT more work, a LOT!

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  • Leo L
    Lv 7
    1 decade ago

    In modern construction, drywall refers to Sheetrock. Sheetrock, as you know, gets finished with joint tape and compound covering the seams and screws. Plaster is a full cover finish. It is smoother and takes paint better. Plaster is now applied over blue-board. This is similar to drywall, but the paper covering is blue instead of grey. The blue paper is moisture resistant, so the plaster can be applied. Drywall would deteriorate from the plaster's moisture.

  • Tom-SJ
    Lv 6
    1 decade ago

    According to Wikipedia,

    Plaster of Paris, or simply plaster, is a type of building material based on calcium sulfate hemihydrate, nominally CaSO4 · 0.5H2O. It is created by heating gypsum to about 150ºC.

    Plaster was a common building material for wall surfaces in a process known as lath and plaster, whereby a series of wooden strips are covered with a semi-dry plaster and then hardened into surface. The plaster used in most lath-and-plaster construction was mainly lime plaster (see below). Lime plaster cure time is about a month. To stabilize the lime plaster during curing, small amounts of Plaster of Paris were mixed into the putty. Because Plaster of Paris sets quickly, "retardants" were used to slow setting time enough to allow workers to mix large working quantities of lime putty plaster. A modern form of this method uses expanded metal mesh over wood or metal structures, which allows a great freedom of design as it is adaptable to both simple and compound curves. Today this building method has been almost completely replaced with drywall, also composed mostly of gypsum plaster. In both these methods a primary advantage of the material is that it is resistant to a fire within a room and so can assist in reducing or eliminating structural damage or destruction provided the fire is promptly extinguished.

    Lime plaster is a mixture of calcium hydroxide and sand (or other inert fillers). Carbon dioxide in the atmosphere causes the plaster to set by transforming the calcium hydroxide into calcium carbonate (limestone). Whitewash is based on the same chemistry.

    To make lime plaster, Limestone (calcium carbonate) is heated to produce quicklime (calcium oxide). Water is then added to produce slaked lime (calcium hydroxide), which is sold as a white powder. Additional water is added to form a paste prior to use. The paste may be stored in air tight containers. Once exposed to the atmosphere, the calcium hydroxide turns back into limestone, causing the plaster to set.

    (end of wiki article.)

    My house was built in 1925 and it appears that all the interior walls are original plaster, about 1/2 inch thick. That suggests it took about 3 coats to apply the plaster. (The backing is strips of wood lath applied to real, full-dimension, rough 2"x4" redwood studs. None of these new-fangled 1.5" x 2.5" pine studs.)

    There would be no need to tape the plaster because there are no joints. Maybe in corners, but I'm not certain that would be needed either with a good corner trowel.

    Plastering takes a lot more time to install than drywall, even when you factor in taping, mudding and sanding of drywall. The three coats is the time-killer for plastering. Plus you have to mix gallons of wet plaster from the dry powder.

    You probably have a 3 person crew - one to mix and supply the wet plaster to the plasters, on hod carriers. They would use wide trowels (9 or 12 inch) to apply the plaster over the lath, and the additional coats. And they are probably walking on stilts or standing on raised platforms to get to the ceiling and upper walls.

    Presently, I doubt that very much plastering is done. Most likely, high end houses that get a 'plastering' look actually get a skim coat or two of plaster, 1/4" thick applied over 1/2" drywall. That way, the look and feel of the final coat is more like plaster than sanded or textured drywall. You get the lower cost installation of drywall and the final appearance of plaster.

  • 1 decade ago

    The advantage of plaster is that it can be in any shape you want, like for a circular stairwell. There are no joints, so no taping is involved.

    The disadvantage of plaster is that it takes a skill level higher than that for taping drywall, where imperfections are hidden by the texture. It costs more, and it is more prone to cracking.

  • 1 decade ago

    Drywall

    More common, faster to install, less labor intensive, less expensive

    Plaster

    Less common, considered higher end, stronger finish, more labor and cost

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