PHOTO of hand split lath and plaster ca 1800 Interior Wall Coverings: How to Identify Types of Plaster, Lath, Drywall, Beaver Board, Upson Board
a Guide to Building Age

  • DRYWALL, PLASTER, BEAVERBOARD - CONTENTS: Plaster & plaster lath types, history, age determination. Beaverboard and Upsonboard interior wall & ceiling product identification. Drywall identification and history of use, gypsum board exterior wall sheathing, drywall identification marks. How to determine the age of a building by examining its individual components: plaster, lath types, lath nail
  • POST a QUESTION or READ FAQs about ages & types of wall & ceiling materials, installations & practices

Guide to beaverboard, drywall, plaster & paneling on interior walls: ages & types of finish materials used for interior walls & ceilings: here we provide a photo guide to identifying types of plaster, lath, Beaver board, Upson Board, and Drywall to help identify these interior building wall and ceiling coverings and as an aid in determining the age of a building.

This article discusses the identification and history of older interior building surface materials such plaster and lath, Beaverboard, and Drywall - materials that were used to form the (usually) non-structural surface of building interior ceilings and walls. Our page top photo shows hand-split wooden lath backing for a plaster interior wall.

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Guide to Plaster & Drywall & Other Interior Wall Coverings as Indicators of Building Age

PHOTO of hand split lath and plaster ca 1800

History of Types Interior Plaster: split wood lath, sawn wood lath, expanded metal lath, "rock lath" or plasterboard, drywall, & tainted Chinese drywall

The age of a building can be determined quite accurately by documentation, but when documents are not readily available, visual clues such as those available during a professional home inspection can still determine when a house was built by examining its components, building materials, even nails, fasteners, and types of saw cuts on lumber.

Photograph of hand-split wood lath and plaster wall, from the wall-cavity side. Ca 1800.

There are several generations of plaster and lath, plaster board, and drywall which have been used in buildings.

We name and illustrate these and discuss their periods of use below as an aid in finding out how old a building is and tracing its history. Examples:

  • Mud used as a plaster over split wood lath or woven wood lath
  • Horsehair mixed with plaster or cement for building exterior wall covering
  • Plaster of paris applied in at least two layers,a rough brown or scratch coat and a smooth white plaster top coat over hand split or sawn wood lath;
  • Plaster of the same general formula was later applied over expanded metal lath.
  • Gypsum board lath: Plasterboard with round holes punched at regular intervals substituted for the plaster scratch coat, nailed to wall studs, eliminating the wood lath requirement. A top coat of plaster was applied to the plaster board. "Ears" of oozing plaster pushed through the round holes helped hold the plaster top coat in place. Essentially synonymous are drywall, gyp rock, gypsum board, plasterboard when used as a backer for a top coat of plaster.

    For details about plaster walls and ceilings
  • Drywall, a lighter gypsum formula, with joints taped with paper (later fiberglass or plastic mesh) and coated with joint compound. Available in 1/4", 3/8", 1/2", and 3/4" thickness, typically 4' x 8' or4' x 12'. Earlier drywall was secured with drywall nails;

    Modern drywall is secured to wall studs using machine-driven drywall screws or in some applications glue as well as drywall screws. Drywall is available in various compositions including "mold-resistant" (dubious,
    see our article DRYWALL MOLD RESISTANT) and fire-resistant materials.

See PLASTER TYPE IDENTIFICATION for a photo guide to different plastering systems used in buildings.

For plaster type surfaces used on building exteriors,

Gypsum Board Lath Sheets Used for Plaster Walls & Ceilings = Rock Lath, Plaster Lath, or Rock Lathe

Plaster lath board © Daniel Friedman Plaster lath board © Daniel Friedman

Our photo (above left) shows perforated gypsum board panels that were used as plaster lath.

Solid gypsum board (above right, without holes) was also used as a support for a plaster finish coat. Often this material was applied in two-foot widths - a feature that the inspector may spot by noticing scalloped ceilings and walls or even cracks that appear regularly on 24" centers.


Expanded Mesh Metal Lath for Plaster Walls

Expanded mesh metal lath for plaster walls and ceilings © Daniel Friedman


Our photo shows expanded mesh metal lath used as plaster lath support for ceilings and walls; this material was also used on building exterior walls to support a stucco finish.

Metal lath was on occasion used also to support poured concrete ceilings (shown here) - unlikely to provide adequate strength for a thick pour unless additional reinforcement was used.

Depending on building age we may find a mixture of multiple types of plaster support, wood lath, gypsum board lath, and metal lath.

Wall or ceiling or stucco crack patterns may follow the borders of metal lath segments, especially if the lath was not securely nailed.


Identifying Stamps on Drywall Used for Interior Wall & Ceiling Surfaces

US Gypsum drywall stamp © Daniel Friedman US Gypsum drywall stamp © Daniel Friedman

Our photos (above and below) show modern identification stamps or labels that may be found drywall products used for interior walls and ceilings. Also see additional drywall identifying number stamps found
at DRYWALL GYPSUM BOARD Used for Exterior Wall Sheathing.

Where there indoor environmental concerns or corrosion damage to electrical wiring, copper pipes, air conditioning equipment, etc. See CHINESE DRYWALL HAZARDS.

US Gypsum drywall stamp © Daniel Friedman US Gypsum drywall stamp © Daniel Friedman

Drywall Gypsum Board Used for Exterior Wall Sheathing

Gypsum board exterior wall sheathing or roof sheathing © Daniel Friedman

We estimate that from 1950 to 1965 gypsum board was used as exterior wall sheathing on a variety of buildings, especially low-cost structures and in panelized construction as we explain along with our photographs shown below.

We also find gypsum board sheathing used on some roofs, believe it or not.

In some applications a water repellent paper was used to improve the product's durability, as we show in this wall cavity side photograph of identifying marks on gypsum board sheathing.


Details: as water-resistant gypsum panels were widely used for exterior wall and roof sheathting we discuss this material separately

see DRYWALL MOLD RESISTANT for an interior drywall reported to resist mold growth.

History of the Use of Wood and other Wall Paneling in North America

Early Colonial Wall Paneling & Wainscoting

Early colonial paneling is described by Isham.

Colonial type wall paneling, wainscot © Daniel Friedman


A concise history of wall coverings in residential buildings, more photos, & dates in process, CONTACT us, contributions invited.

Shown at left, colonial style wall paneling in the historic Suffolk Resolves House (1774) in Milton MA.


Wainscot Wall Covering

Wainscoting or "wainscot" is a wood wall finish applied to the lower portion of a building interior, typically about three to four feet up from floor level, and usually capped with a chair rail and usually applied with board edge joints butted vertically as in our photo.

Wooden veneer wall paneling © Daniel Friedman

Traditional wainscot is constructed by nailing individual boards to the wall surface.

Modern "wainscot" panels are sold in 4' x 8' sheets and cut to fit, producing a beadboard surface that looks like traditional wainscot.

Wainscot is an old term, possibly from the 1300's, that in its contemporary usage derives from the British Wainscot, "a fine grade of oak imported for woodwork" - Merriam Webster.

In North America wainscot has been in use since the colonial era.

Our photo (left) illustrates beadboard type wainscot wall paneling in a Victorian home built in Poughkeepsie, NY in 1900.

Wooden wall paneling - tongue and groove pine and other woods

Pine paneling © Daniel Friedman

Wooden wall paneling made of individual boards, often tongue-and-groove common or knotty pine, was most often nailed vertically from floor to ceiling and finished with wall trim at both of those levels.

In North America solid vertical tongue-and-groove pine paneling on building interior walls was particularly popular from about 1945 through the 1960's.




Wall paneling in 4' x 8' sheets

Wooden veneer wall paneling © Daniel Friedman

By the 1970's in the U.S. and Canada, the use of solid tongue-and groove wall paneling was more often replaced by thinner 4' x 8' sheets of wood veneer paneling sections.

Shown at left is a typical thin plywood veneer type wall paneling installed in the 1970's. A concise history of veneer-type wall paneling in residential buildings, more photos, & dates in process, CONTACT us, contributions invited.




History of Beaver Board & Upson Board Wall Coverings in North America

Beaver-board and Upson Board are a wood fiber product used as an inexpensive interior wall covering and draft blocker from about 1903 when Beaver Board was invented by J.P. Lewis in Beaver Falls, NY, to the 1950s, with its near-twin product Upson Board continuing in use into at least the 1980's.

Our photographs (below) show this product from it's back or wall cavity side. On the exposed side this wood fiberboard product was usually painted and its joints covered with wood lath or other trim. In some applications it was covered with wallpaper. In some homes it was later covered with drywall to provide a more fire-resistant surface.

Beaverboard wall covering © Daniel Friedman Beaverboard wall covering © Daniel Friedman

Beaverboard takes its name from the Beaver N.Y. and the Beaver Board Companies that produced this product until that firm was purchased by Certain Teed Prod cuts in 1928. Beaver Board and Upson Board were produced by the Beaver Wood Fibre Company Limited, in Thorold, Ontario.

Beaver board's competition was from Upson Processed board (John Upson, Upson Company, Lockport, NY) which was produced beginning in 1910. As late as the 1950's Upson Board was used in prefabricated houses and exterior building sheathing and in recreational vehicles. Upson purchased the Beaver Board plant from CertainTeed in 1955. Upson began its decline in the 1970's and closed in 1984, opening later that year as Niagara Fiberboard.

Beaverboard and other paper or fiberboard products were used for exterior wall sheathing, as we show in this photograph at left.

How to Identify Beaver Board and Upson Board

Beaver Board trademark © Daniel Friedman

Beaver Board was marked on the back of each sheet with an ink-stamped trademark and brand.

Upson Board Trademark

Upson board embossed its marking into the board itself, and a "Blue Center" runs through every piece of the board.

Examine a cross section of the board for this characteristic blue material.

Portions of this material were derived from Weaver.

See SHEATHING, FIBERBOARD - Sheathing Celotex Homasote & Other for a discussion of exterior wall sheathing fiberboard products such as Homasote® and Celotex® insulating roof, wall, and foundation board products. There we also include photographs of insulating wallboard products that have been attacked by mold or insects.


Masonite™ and Other Hardboard Interior Wall & Ceiling Products: Identification

Masonite hardboard © Daniel Friedman

Masonite hardboard panels are often found as a utility cladding in buildings on walls and ceilings. This article explains the utility usage of hardboard interior products, and we exclude wood or wood-like wall or ceiling paneling products.

Those are discussed
at HISTORY of the USE of WOOD & OTHER WALL PANELING in North America.


Also see MASONITE™ used in strutures.

(History, more photos, & dates in process, CONTACT us, contributions invited)



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