The difference between drywall and plaster is easy to tell. Just use a thumb pin and try to push it into the wall using just hand pressure. If the thumb pin goes in smoothly on minimal pressure then it is drywall. If it does not go in smoothly then it is plaster. As plaster is much harder when compared with drywall it does not allow a thumb pin to go in easily. This can be the most reliable test to distinguish between plaster and drywall.
If you are viewing a property and the realtor or agent does not allow you to poke thumb pins into walls then you can also try the second test. Try to push the wall with your finger. If the wall gives in, i.e. it flexibly moves a bit inward at the spot of pressure along the applied force trajectory then it is drywall. As drywall is much more flexible than a plastered wall it has a tendency to give in when direct pressure is applied. Plastered walls don’t allow any flexibility. Hence, a plastered wall will not give in.
Drywall is just a board made up of gypsum compound and is lined with backer paper and is extruded between thick sheets of a facer. Drywall is like a board that is just nailed to the wooden frame of the house.
In contrast, plaster is a paste-like compound. It is usually applied on top of a brick or concrete block wall. The plastering causes the wall to become smooth and flush and also hides the bricks or construction blocks.
In the US plastering is mostly used in commercial buildings and complexes made of concrete blocks, while the homes usually have drywall. This is because wooden houses are common in the US and drywall can easily be nailed to the wooden frame of the house.
How do I know what type of wall I have?
Just use one of the tests I mentioned earlier and use it to distinguish the type of wall. Usually, if you have a wooden house you will most likely have drywall. If on the other hand, you have a brick or a concrete block house then you will most likely have plastered walls. Applying drywall on top of bricks only raises the cost and does not benefit the house in any way. Hence, most housebuilders will only plaster brick walls.
When did they start using drywall instead of plaster?
Drywall was invented in 1922. It was portrayed as a fireproof alternative for wooden houses. However, it did not catch on till the 1940s when the increased demand for houses caused them to be used widely. Drywall does not require the house to be plastered, a process that takes almost 1 to 2 months. Thus drywall saves builders time while building multiple single housing units and hence it became popular just for this reason alone. However, it is certainly not as reliable and as durable when compared with plaster.
What is the difference between drywall mud and plaster?
Drywall mud or joint compound is a gypsum-based paste. It is used to finish the corners while installing drywall. It is not meant to cover the whole of the drywall. Drywall is itself made up of gypsum extruded between thick sheets of facer and backer paper. Hence you do not apply drywall mud on top of the drywall.
This is contrary to plaster. Plaster must be applied to the whole wall end to end. It requires a lot of labour and needs to be finished smoothly so that it comes flush with the rest of the walls in the room and the doors.
Hence drywall and plaster application differ significantly. While drywall can just be nailed in plastering is an art and must be done slowly and carefully.
Drywall is also hard to fix cracks and holes on when compared to plaster. If there is a hole in the drywall you would need to stick a patch of drywall behind the hole i.e. on the surface that faces the frame of the house. Then you would use drywall mud to cover the hole from the front.
If there is a crack in an old plaster all you will have to do is patch it up using more plaster.
Can you apply plaster over drywall?
Yes, you can. But you shouldn’t. Let me explain. Plaster is made up of cement and sand while drywall is a gypsum-based compound. Hence the two do react and form a bond which means that plaster will stick to drywall without any problems. But doing this makes no financial sense. If you have drywalled your house why are you trying to plaster it? If you have a few cracks and holes in the drywall you can just patch them up using a 2×4 for back support behind the hole and drywall mud to fill the hole.
You don’t need to plaster drywall under any situation. Period.
What is the difference between drywall mud and joint compound?
Both drywall mud and joint compound are the same things. There is no difference between the two. It is just a name difference between the different states in the US. It is a gypsum-based compound that is used to fill the gaps between the drywall sheets.
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