PHOTO of hand split lath and plaster ca 1800 Interior Wall Coverings
A Guide to Building Age & Choices of Wall Sheathing or Coverings Indoors

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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.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

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

PHOTO of hand split lath and plaster ca 1800

Article Series Contents

Above we show a 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.

[Clickt to enlarge any image]

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.

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.

Asbestos Cement & Fiber Cement Fireproof Ceiling & Wall Panels

Asbestos millboard (C) Daniel Friedman

Asbestos-cement panels and later non-asbestos-containing fiber-cement panels were widely used as fireproof coverings for walls, ceilings, even floors in various applications such as in boiler rooms as well as in chemical laboratories and other areas where an inert, durable, fire-resistant surface was needed.

See CEMENT ASBESTOS SHEET PRODUCTS for the age, history of and details about cement-asbestos fireproof panels used in and on buildings.

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.

Details about BeaverBoard used on interior walls and ceilings are found at BEAVERBOARD in our article on building sheathing materials identifcation.

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. at references.

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.

Drywall, Gypsum Board, Plaster, Stucco & Their Predecessors

Sawn wooden lath and loose plaster (C) Daniel Friedman

Above photograph shows the more-regular width sawn wood lath used to support plaster in a home constructed ca 1865.

Ceiling & Wall Covering Materials Using Plaster, Drywall / Gypsum Board, or Stucco

How is drywall made & what are the ingredients of gypsum wallboard ("drywall" or "Sheetrock™") ?

According to an ATSDR study of asbestos exposure from vermiculite and some forms of drywall, gypsum wallboard is currently (2008) manufactured in the following steps:

  1. Gypsum rock is crushed to form small pieces, dried to evaporate surface moisture, and ground;
  2. The dried gypsum is “calcined” or heated to remove excess water that is chemically bonded to the gypsum, forming what is called “stucco;”
  3. Dry additives (e.g., vermiculite, perlite, starch, fiberglass, or sugar) are mixed into the stucco depending on the properties needed in the specific product;
  4. Water is added to produce a slurry;
  5. The slurry is mechanically spread over a paper backing;
  6. A top layer of paper backing is applied to form a “sandwich” with the slurry in the middle;
  7. The long, continuous sheet of wallboard moves on conveyor belts while the slurry hardens, and the sheets are cut into specified lengths;
  8. The cut boards are flipped and sent into a multi-stage kiln to dry and become hard; and
  9. The hardened wallboards are trimmed to an exact length, end-taped, stacked, and placed onto skids, ready to be shipped.

Identifying Stamps on Drywall Used for Interior Wall & Ceiling Surfaces

Our photos show modern as well as antique identification stamps or labels that may be found drywall products used for interior walls and ceilings. [Click to enlarge any image]

Celotex gypsum board identification (C) Celotex gypsum board identification (C)

Above: Celotex® Fiberglass-reinforced drywall identification labels & UPC

Contact Celotex:

US Gypsum drywall stamp © Daniel Friedman

[Click to enlarge any image]

Above: Factory Mutual Audit Inspection Stamp on 1/2" gypsum wallboard that is 1-hour factory rated.

Below: FM Gypsum brand wallboard, type FSW giving fire ratings.

US Gypsum drywall stamp © Daniel Friedman

Contact FM Approals: Website:, Worldwide office locations website:
Website Excerpt:

FM Approvals continues to test and certify key products related to property loss prevention. Our dedication to innovation over the years has resulted in numerous technical advancements, including low smoke generation wall panels, clean room materials, suppression mode sprinkler protection and water mist systems.

Below: a stamp identifying Ignifuge Gyprock fire protective gypsum board, a Canadianproduct.

Ignifuge Gyprock fire rated drywall, Canada (C) contributed by an anonymous reader

Contact: Saint Gobain Gyproc Corporation, Saint-Gobain, Website: Saint-Gobain S.A. is a French multinational corporation located in Courbevoie, France.

Below: National Gypsum drywall stamp on a U.S. home built in Ann Arbor MI in 1958. The image was contributed by an anonynous reader.

We think this drywall was installed in an Ann Arbor Michigan home built in 1958 during basement renovation, possibly in the 1970's. Readers recognizing this stamp are invited to CONTACT us to offer more information.

National Gypsum drywall on a basement ceiling, estimated ca 1970 (C) -D.N.

According to our reader, the gypsum board shown above was tested and found to contain NO asbestos. [Private email 2018/03/29]

National Gypsum produced and sold a number of asbestos-containing drywall / gypsum board products until the early 1970's, may under the Gold Bond name, also Insul-Best panels.


Below: an Underwriters Laboratories wallboard fire-rating stamp

US Gypsum drywall stamp © Daniel Friedman

Below: a United States Gypsum drywall stamp from an older home.

US Gypsum drywall stamp © Daniel Friedman

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. be sure to see CHINESE DRYWALL HAZARDS.

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 at SHEATHING, GYPSUM BOARD

Also see DRYWALL MOLD RESISTANTfor an interior drywall reported to resist mold growth.

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

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.

According to some patent disclosures (given below on this page) non-perforated gypsum board panels used as a plaster base included versions with depressions or indentations to better-receive and ahere the plaster top coats.

At PLASTER TYPE IDENTIFICATION we include more-detailed discussion of GYPSUM BOARD PLASTER LATH SYSTEMS - perforated or solid gypsum boards as plaster base: "Rock lath", including the history of use of "rock lath" or perforated gypsum board or "button board" as a plaster base or lath-substitute material.

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.

See PLASTER LATH, METAL for details about the types, uses, & installation of expanded metal lath.

See PLASTER TYPE IDENTIFICATION for details about plaster used in or on buildings. .

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)

Bathroom & Kitchen Laminated Hardboard Panels

Laminated hardboard used  as a bathtub surround in an older U.S. home (C) Daniel FriedmanLaminated Masonite® and other hardboard products have been widely used as water-resistant panels to cover walls and sometimes ceilings in bathrooms, kitchens, and other work areas. A hard thin plastic laminate was applied to the hardboard surface to simluate marble, tile, or other materials.

Laminated hardboard was widely used in other applications as well, including baby furniture, lab surfaces, RVs, cabins, ornamental wall wall coverings simulating tile, in various pre-fabricated structures, and even in some automobile door panels and airplane panels.

Cleverly the U.S. army used a shipping crate for latrine parts that combined tempered Masonte or the like panels that formed a lining to convert the shipping crate to a latrine enclosure. (Sheffield 1955).

Above: laminated hardboard as a bath tub surround in an older U.S. home. Scratches or nicks in the surface of the hardboard allow water to penetrate, causing the dark brown ringed stains at this tub surround.

Other water penetration in older hardboard wall coverings can cause the formation of a roughened or rippled surface.

When water damage is severe the hardboard softens, swells, and may leak into the wall cavity.

See also IDENTIFY Masonite™ and other hardboard Sheet and Siding Building Materials

Because of its lighter weight and alternative production means hardboard-based wall and ceiling coverings found a place where previously cementious products such as asbestos cement or later fiber cement board was used on walls and ceilings as a fireproof wallboard. Also see CEMENT ASBESTOS SHEET PRODUCTS

Below: another coated Masonite® type hardboard used around a bath tub.

Laminated hardboard used  as a bathtub surround in an older U.S. home (C) Daniel Friedman

History, Research, Examples of Unitized Bathroom Wall & Ceiling Coverings & Tub Surrounds Using Coated or Laminated-Surface Hardboard

Wood Lath Systems Supporting Plaster or Stucco in Older Homes: Hand split vs. Sawn Wood Lath

PHOTO of hand split lath and plaster ca 1800

Above and also in another photo shown earlier in this article series, we include a photograph of hand-split wood lath and plaster wall, from the wall-cavity side of a U.S. home built around 1800. There are several generations of plaster and lath, plaster board, and drywall which have been used in buildings.

Details about the types of wood lath used to support plaster or stucco on building walls, ceilings, or exteriors are at WOOD LATH for PLASTER or STUCCO.

Inspecting old interior walls with care can yield interesting and perhaps useful historical information about the structure. Below I'm demonstrating that this plaster-lath wall also sported four layers of wallpaper atop the originally-plastered wall surface.

Multiple layers of wallpaper on an old plaster wall (C) Daniel Friedman

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.



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