Stucco Classico: Plaster Repair for Pennsylvania

We serve eastern and western Pennsylvania and vicinity.

About Plaster Repair:

"Plaster" is actually a broad term used to describe the material covering your walls and ceilings.  Plaster systems changed considerably throughout the twentieth century and into today.  Typically, every twenty years "new and improved" systems were made available with different materials and techniques.  Plaster repair methods and materials vary with each system.  You can be assured that we will match the original material closely, to give you the longest lasting plaster repair possible.  We do the minimal amount of demolition, to preserve as much of your original plaster as possible and save you money.  To make use of the information here, try to determine the approximate era that the plaster was installed, then select from the appropriate option below.  Some of the systems of plaster that have been used in this country include:

1. Up to 1910s: One or two coats of lime stucco, followed usually by a finishing coat of putty lime and gauging plaster.
2. One or two coats of gypsum plaster over wood lath, with finish coat of putty lime and gauging plaster.
   This system, with harder materials than lime stuccos, became prevalent in the 1920s.  Wood lath remained dominant, while straight corner beads made their first appearance.  If your house is from this period, any curved shapes were usually made by hand, while straight corners are normally beaded.  Plaster repairs are easy around beaded corners, but a mold is usually required for curves.  Metal lath becomes prevalent, either as a supplement to wood lath or in place of wood lath.  Wood and metal lath-based plasters are the most durable and generally require the least amount of demolition.
3. gypsum lath (3/8") and one or two coats of job mixed sanded base coat, with a finish coat.
   Gypsum lath caught on in the 1930s.  Gypsum lath looks similar to drywall, but has a different facing.  Sometimes it has perforations in the board.  The gypsum lath, called "Rock Lath," was in sheets usually 16" X 48".  Seams were not taped.  The boards were nailed to the framing members.  Though it saved labor, this material is generally inferior to wood or metal lath based plasters.  Like drywall, the rock lath base is very vulnerable to water damage.  Long straight cracks usually appear where there are seams between boards, as the boards work loose.
4. gypsum lath (3/8") and one coat of factory mixed plaster with expanded light weight aggregate and finish coat.
   This system caught on during the fifties.  The expanded aggregate, typically perlite or vermiculite, saved weight, but made the plaster mix a bit weaker.  Sometimes this system develops sags between joints.  It, too, is prone to long straight cracks as the lath works loose over the years.  In cases of water damage, gypsum lath usually suffer a delamination of the thin finish coat.  If the water is minimal, it is possible to merely re-skim.  However, in most cases the water causes the bases layers to swell.  This not only eliminates the possibility of leaving a straight finish coat, but the structural integrity of the system is compromised.  In this case, damaged areas must be removed.
5. Hardcoat, consisting of 5/8" or 1/2" blueboard, taped and covered with two thin coats.
   This system eliminates the long straight cracks, but is more vulnerable to water.  Because of the thinness of the coats, the framing must be straight, as there is little chance to straighten out the wall or ceiling.  The surface is abrasion resistance and eliminates many of the visual flaws of poorly installed drywall.

We service the systems above, excluding modern hardcoat.  We can avoid surface taping in almost all cases.  We find that most of the repair techniques typically used to today on plaster by the well-meaning but non-experts typically are done with inferior materials, such as drywall tape and mud.  Tape unavoidably leaves a bulge that must be hidden.  Moreover, it does not address the root of the problem, which is usually loose plaster.  Using pieces of drywall to fix plaster is a bit like using junk parts to repair your Rolls-Royce.  Drywall does not have the same performance characteristics as plaster and stucco.  Incorrect mixes can actually damage existing plaster, so we use actual plaster materials like the original materials and avoid synthetics when practical.  We do not use plaster washers to reattach loose plaster (except temporarily).  We do rely on proprietary acrylic-based adhesive, as it allows us to save plaster that would otherwise have to be destroyed or badly repaired.  No bumps are left behind, and the system is flexible.

More information can be found in the following NPS brief: NPS brief 21  Note: we disagree with some of the methods suggested for repairs, but the explanation of plaster is excellent.

Repair Project Images:

Repair of Ceiling and Arched Window Niche

(Ceiling Repair and Running a Plaster Arch in situ)

Basic Repair of 1950s ceiling

Basic Repair of 1920s ceiling

Repair of Lime Stucco with Ornamental Gypsum Moulding

Water damage repair to ornamental plaster.  Base coats are lime stucco.

For expert plaster repairs, contact Stucco Classico.