Many of the Des Moines’ historic homes were built with plastered interior walls. Because it is so labor-intensive (and therefore expensive), plaster is not considered a standard building practice in today’s construction industry. A plaster wall is constructed in several stages. First, small strips of wood called lath are nailed across the studs (walls) and the bottoms of floor joists and rafters (ceilings). Plaster is typically applied onto the lath in three layers. The first layer is the thickest and applied directly to the lath. As it is applied to the wall or ceiling, some of the plaster gets pressed through the horizontal spaces between the lath strips. These “keys” harden and became the supports that hold the plaster to the wall or ceiling. The second layer of plaster is much thinner and helps level the surface. The final layer consists of a mixture of lime and plaster, or plain lime putty, and is applied to a thickness of approximately 1/8” before being floated to a near-flat surface.

You will find it is very difficult to remove small areas of plaster without damaging the surrounding area – if the “keys” that hold the plaster to the lath fall off, the plaster itself becomes very weak. It is likely that during your renovation, you will either completely remove the plaster or significantly damage areas of plaster in order to update the electric, plumbing, and HAVC systems.

Drywall

In these areas, you will likely replace the plaster you remove with drywall. Drywall is a “sandwich” of gypsum between two layers of paper backing. It is fabricated in sheets that come in a range of sizes 48” wide by 8 to 12 feet long. Larger drywall suppliers have a truck with a crane and will, for a fee, hoist the drywall into second and third-floor windows and distribute it throughout the rooms. Particularly in buildings with tight stairways or small hallways, it may be impossible to carry a full sheet between floors, so this service can be invaluable.

Sometimes a vapor barrier is installed between the insulation and the drywall. A vapor barrier is a plastic sheeting that prevents air and moisture infiltration into the building and can improve its energy efficiency. A vapor barrier must be installed on the “warm” side of the insulation or moisture can condense inside the wall and cause significant damage.

Hanging and Taping

A finished drywall surface happens in two stages: hanging and taping. Hanging drywall takes some muscle, but with the right tools and some persistence, the skills are relatively easy to acquire. If you have never hung drywall, ask someone with experience to help you for a few hours until you understand the process. Most general “how-to” books contain sections on hanging drywall.

Essentially, large sheets of drywall are screwed or nailed to the studs and joists to create a flat surface. Screws will create a stronger connection than nails and will result in fewer “pops” where the connector becomes visible as the house shifts or settles.

Tools required for installing drywall include:

• Cordless drill (with spare battery and charger)

• Utility knife (with plenty of spare blades)
• Drywall square (a four foot "T" shaped tool)
• Keyhole saw
• Tape measure
• Chalk line, and
• Carpenter's pencils

A drywall lift is a hand-cranked lifting platform for holding sheets of drywall when hanging the ceiling. Using a lift makes the job manageable for even a single person who has the strength to move a whole sheet onto the lift.

It is generally best practice to install the largest piece of drywall that will fit in a space, minimizing the number of joints. It is also best practice to install full sheets of drywall perpendicular to the studs or joists in order to minimize “pops” and cracks. In cases where the sheets must be cut, it is scored through the paper on one side with a utility knife and snapped by bending. Cutting the paper on the opposite side then separates the piece.

Managing Drywall Installation

If you hire people to hang and tape the drywall, there are some things to look for before releasing their final payment. The primary issue is quality - to check the quality of the taping, take a high-powered construction lamp (halogen) and place it near to the wall, shining it each direction. Rough areas, bumps, and depressions that should be dealt with will cast shadows along the wall. Also veryify that none of the electric boxes have been covered up. If any are covered up, the electrician will likely forget to install the appropriate fixture. For example, you don't want to get caught in a situation where your building inspector is performing the final inspection and notes a "missing" smoke detector. The drywall installer can locate the covered electric boxes using a long level and noting any "bulges" in the ceiling (properly installed boxes protrude beyond the stud or joist).