The invention of sheetrock installation for interior wall sheathing revolutionized the building industry. By being able to finish a wall with a series of panels not only sped up the building process but lessened the reliance on a skilled trade. Because learning to hang and tape drywall required far less of a learning curve than the skills required to be a master plasterer.
Plaster and Lath
Up until the late 1940's the interior of homes were finished by attaching rows of 1/2 X 2 wood strips called lathes which were cut in lengths to fit on the studs of the new home. These were then nailed and every flat surface besides the floor was covered in the same way. Following behind the lath carpenters were the plasterers who coated the wood strips with a gypsum compound that would form the wall surfaces. On the average a team of lath and plaster installers could finish a home in two weeks whereas drywall installers can finish the same amount of area in 3 days.
Before the 1900's a limestone plaster was used. This was extremely hard deriving its durability from the compound itself and the addition of animal hair. In the early part of the 20th Century gypsum took the place of limestone but the application was similar. A scratch coat was swathed onto the wood laths to form keys, plaster that was squeezed through the 1/2 openings between the laths. This formed a base for the wall. The second coat was called a brown coat, also a rougher mix which would be gritty enough to hold the finish coat. Finishers pressed the topcoat hard so that it formed a smooth finish, more striking than a drywall surface.
Drywall or Sheetrock
The American home front of World War II demanded new structures that had to be built quickly and cheaply. These houses and buildings were needed to house the millions of recruits, factory workers and bureaucrats needed to mount a full-scale war. Beauty and creativity had to be pushed aside for speed so a previously-shunned product called Sheetrock was drafted along with the fighting men and women. As well, drywall installation cost was a fraction of what it cost for crews to plaster. And despite the flimsy appearance of the paper-covered gypsum walls the post-war homebuilders appreciated the inexpensive application and soon drywall was an integral part of the new housing boom of the era.
The drywall sheet begins as a wet mash of gypsum plaster mixed with paper or fiberglass fibers, potash plus a foaming and plasticizing agent. This material is then sandwiched between two layers of heavy paper and shaped and flattened into sheets. After it dries the sheets are doubled and taped together with the good, paintable side in for protection in transport.
The Drywall Process
Most homes are frame-built with vertical wood or pressed-steel studs set at 16 centers. The 4' X 8' drywall sheets are hung either vertically or horizontally onto the studs with screws. As the lengths and widths are multiples of 16 the sheets fit the studs with little wastage. Screws are used at intervals on all the studs behind the sheet to secure it. However, the drywall installer is careful not to use too much force or the heads will go through the paper covering.
When the sheet has to be cut to fit the area a large T-square is used as a guide for a utility knife. The knife is drawn along the straight edge cutting through the paper layer. Then the smaller piece is pushed against the cut to break the bond. Folding the breaking piece over the knife is drawn up underneath and the second paper layer is cut through. Outlets and light switch holes are measured before the sheet is put up and these holes are cut out. The sheets are installed with special drywall screws.
The inner corners are covered with drywall tape but outer edges are usually crowned with a metal strip that is fastened to both sheets. Once this is done then the mudding begins.
A skim coat of drywall compound, or mud, covers seams, screw heads and inner corners. Then the drywall tape is pressed on the wet compound and covered with another coat of the mud. All screw heads and mars on the surface are then covered. A good drywaller is careful not to use too much mud because it will have to sanded off later creating more of a mess than needed.
After the first coat dries this is lightly sanded and then a heavier coat is put on which bring the compound up to the surface of the drywall. This is then sanded to a smooth finish and the surface is ready for painting.
There is a lot of information available on how to drywall. However, although drywalling can be a do-it-yourself project, it is best to get a professional sheetrock installation done. These tradespeople are not only fast but they can accomplish the job with the least amount of mess. Because sanding the drywall compound does create dust. You can find sheetrock contractors in our Contractor Directory or post you project online and get them to contract you.Posted by: TrustedPros