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PHOTO of hand split lath and plaster ca 1800 Types of Wood Lath Used for Plaster or Stucco
Photos & description of hand spit & sawn wooden lath strips

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Types of wooden lath used to support plaster or stucco:

This article describes and illustrates hand split wooden lath, straight-sawn or pit-sawn wood lath, and more modern circular-sawn wood lath that have been used in the construction of plaster or stucco-covered walls, ceilings, and some building exterior surfaces for hundreds of years. Recognizing the type of lath used to support plaster or stucco can help determine the age of a building.

This article series 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. At page top 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.

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.

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

PHOTO of hand split lath and plaster ca 1800Here and at the top of this article 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.

[Click to enlarge any image]

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

The irregular width and rough surface of the hand-split wood lath tells us that this building used wooden lath strips to support plaster (or sometimes stucco) on a building where hand-sawn lath was not yet available.

Below in our first photo we see regular width sawn lath from Brinstone Farm, Ste. Weonards, in Herefordshire in the U.K. Buildings in this area date from the 1600's.

Just when sawn lath replaced split lath in building construction depended on when sawmills were available in the area - a date that varies by more than 200 years depending on the country and province.

 

Below in our second photo showing both plaster and wooden lath, we see regular-width sawn lath strips supporting (now loose) plaster in a home constructed in the mid 1800's in New York.

Wood lath at Brinstone Farm at St. Weonards in Herefordshire, U.K., (C) Daniel Friedman Sawn wooden lath and loose plaster (C) Daniel Friedman

Watch out: loose plaster can be dangerous. See PLASTER, LOOSE FALL HAZARDS

You can detect the presence of wood lath behind some plastered surfaces even when the lath is not directly visible.

Below: the regular, parallel, uniformly-spaced lines in this thin-coated plaster attic ceiling of a pre-1900 New York home (shown above) indicate the presence of sawn lath supporting this ceiling and wall plaster.

Plaster lines confirm that this is a wood-lath installation (C) Daniel Friedman

After illustrating three generations of types of wood lath support for plaster on interior walls or as stucco on exterior walls we will discuss each of these types in more detail.

Riven or Hand Split Wood Lath Based Plaster Ceilings & Walls

PHOTO of hand split lath and plaster ca 1800

Photograph of hand-split wood lath and plaster wall, from the wall-cavity side. Ca 1800. Hand split wood lath will vary in width as you see in our photo.

Hand split wood lath was prepared using an adze, or less often an axe, to split lath strips out of sawn or hewn logs.

Below: click to enlarge each of these wood lath photographs and you can see split marks (and raccoon claw scratches) on hand split wood lath.

Hand split wooden lath used for plaster or stucco (C) Daniel Friedman

Hand-split lath will vary in width both between lath strips and often along the length of an individual wood lath strip such as you see in our photo above.

Sawn-Wood Lath Based Plaster Ceilings & Walls

Sawn wood lath based plaster © D Friedman at InspectApedia.com Our photographs show traditional sawn wood lath used as the supporting base for a typical three-coat plaster ceiling or wall system.

In North America after about 1830, sawn lath was made on pit sawn (angled saw kerfs), reciprocating sawn (straight saw kefs), and circular sawn (curved saw kerfs) equipment, but sawn lath was far more widely-used where circular saws made possible the production of large quantities of machine-sawn lath boards.

Sawn wood lath will usually be regular in width (1 to 1 1/2") often of regular lengths that span several wall studs (48"). Some early forms of wood lath may be sawn on just the flat sides and edges may vary when wide boards were split.

As with the older split wood lath, plaster of paris was applied in at least two layers, usually three layers: a rough brown or scratch coat and a smooth white plaster top coat over sawn wood lath.

In our photo of split wood lath in an older New York home, you can see the "ears" or "plaster ears" formed by the plaster base coat, or brown coat (the first plaster layer) applied onto the wood lath of this antique New York home.

You'll also notice that especially in older structures whose interior partition walls often used minimal and irregularly-spaced framing for interior walls and ceilings, the plasterer sometimes tacked up an extra wood scrap (the diagonal log in our photo at left) to improve support for plaster lath, or to provide a nailing surface to secure the ends of wood lath that otherwise did not reach a vertical wall stud.

Watch out: often the framing supporting plaster ceilings in homes built before 1900 was sized to be just strong enough to support the weight of the plaster itself. Such ceiling structures were not intended to support the weight of a curious home owner or home inspector.

Below (left) is a photo of an 1870's home in "the Bleachery" in Wappingers Falls, NY, restored by the author (DF). Most of the plaster ears had broken away and plaster was falling from the walls and ceilings in this home. Using a flat-bladed shovel we elected to remove all of the loose plaster.

Our second wood lath plaster photo (below right) is particularly interesting because at least one of the wood lath sections shows the vertical, but regularly-spaced saw kerf marks of a machine operated pits saw, a means of cutting wood used before circular saws were available and helping to date this building as pre 1840 in New York.

Plaster lath board © Daniel Friedman

Below: vertical parallel saw kerf marks on wood lath of a plaster wall found in a home built in 1913 in Poughkeepsie, New York.

Vertical saw kerf marks on wood lath plaster wall (C) Daniel Friedman

Below: unlike the almost dead-staight saw kerf marks in the machine-driven or mechanical pit saw cut lat above, our next photo illustrates wood lath cut on a circular saw.

The saw kerf marks are slightly curved, indicated by our red lines. This photo was contributed by an anonymous reader concerned about possible mold growth on the lath. [Click to enlarge any image]

Plaster lath cut on a circular saw (C) InspectApedia.com JM

More about using saw kerf marks and other tool marks on wood to determine the age of a building can be read at SAW & AXE CUTS, TOOL MARKS, AGE.

Below: our first photo shows how a thin coat of plaster telegraphs the locations of openings between individual wood lath strips.

In a thin plaster coat over wood lath, the plaster that is forced between the lath gaps to form plaster ears may leave the horizontal lines at the lath gaps, as indicated by our yellow dashes.

Plaster lath board © Daniel Friedman Wood lath cut on two different saws (C) Daniel Friedman

Above, our second photo shows that the plaster lath on this wall was cut by two different saws, a vertical reciprocating or mechanically-operated saw (upper photo) and a curved kerf marks showing that some of the lath was cut on a circular saw.

I'd expect to see mixed saw-cut lath in a building that was constructed at a time and in an area of saw mill transition where both types of saw cut lath were available, or (less likely) in a building that was repaired or that used salvaged (older) lath on some of its wall areas.

Below we illustrate the plaster ears of mud-plaster used on wood lath strips, seen from the wall cavity side.

Mud straw plaster © D Friedman at InspectApedia.com

The mud plaster in this example was simply a mud-straw mix of "plaster" base coat used in a late 18th century New York home, ca 1785.

Machine-Sawn Straight-Cut Wood Lath

In ou wood lath photos below on at least some of the lathing strips you can see parallel saw kerf marks telling us that this wood lath was cut by a machine-opeaterd vertically-reciprocating pit saw.

Pit-sawn wooden lath (C) Daniel Friedman Straight cut sawn wood lath (C) Daniel Friedman

Earlier wood lath that was hand sawn using a hand-saw or a hand-operated pit saw will have roughly parallel marks but cut at varying angles across the wood.

Machine Cut Circular Sawn Wood Lath

In the next close-up photo of wooden lath given just below you 'll notice the rounded kerf ridges left by a circular saw on this sawn wood lath.

Circular saw kerf marks on sawn wood lath supporting plaster (C) Daniel Friedman

Also see SAW & AXE CUTS, TOOL MARKS, AGE.

Below all of the wood lath on this wall has been exposed by the author [DF] during renovations of 28 West Street in Wappingers Falls, NY.

This home, located in "the bleachery" district of the village, was constructed in about 1880 or earlier.

Wood lath plaster demolition (C) Daniel Friedman

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

Accordion Lath Plaster Base

Accordion lath in an older New York home (C) InspectApedia.com Preston Accordion lath in an older New York home (C) InspectApedia.com Preston

Accordion lath, used as a plaster base on homes in the northeastern U.S. was made from thin, wide sawn or possibly adze-split boards 1/4" thick or less. Wide boards were more-often available earlier in U.S. construction as old-growth trees in New England were often quite large in diameter.

The thin-split or thin-sawn accordion lath boards were nailed in space and then split along their length using an axe or hatchet to create openings through which plaster could be pushed to form plaster ears securing the plaster to the walls.

The plasterer preparing the lath may have nailed the top of the lath to the wall studs or to a post and beam structure sporting additional vertical lath nailers. With the top of the lath in place it was split and then pulled down and further nailed to keep the splits open.

We estimate, pending further research, that accordion lath was faster to install but unless it was split to provide 3/16" to 1/4" gaps, the plaster had to press rather hard on the base coat to force plaster through small splits to get a good bond with the wall.

In the accordion lath photos shown here the splits are rather small, making this a difficult plaster job. The plasterer would have had to either use a too-liquid plaster scratch coat mix or would have had to press quite hard on the plaster to force it through these small split lath cracks to get a good mechanical bond between the plaster and the accordion lath.

According lath nails, machine made help date this structure (C) InspectApedia.com Preston

Because the lath nails used in this accordion lath installation were observed to be machine-made, yet the lath appears to have been sawn from wide trees, we guess the age of this lath as between 1820 and 1850.

More about the nails used in this building is at NAILS & HARDWARE, AGE.

These photographs and description of accordion lath were provided by an InspectApedia.com reader June 2018. This accordion lath was found in a rural U.S. post-and-beam home in Wyoming County, New York.

Preservation & Repair of Historic or Antique Plaster & Lath

Question: how old is this wood lath and how was it made?

Wood lath age discussion (C) InspectApedia Dean2018/06/09 Dean P said:

Any informartion on the attached photo showing lath board, which appears to be a single piece but split/ expanded for applying plaster?

How was this made and around what time frame was this method used? Thank you - Dean P.

This Q&A were posted originally at PLASTER TYPES & METHODS in BUILDINGS

Reply: see the discussion of accordion lath in the article above

Initial response: Dean:

Here is what I can see and questions I ask about the old wood lath in your photo:

From what I can see so far, and pending your answers to questions I pose below, my preliminary guess is that the wood lath in your photo, IF it is in a building in North America, was probably installed no earlier than 1840 if your building is near or on the East Coast of the U.S. or Canada, and probably closer to 1900.

...


Continue reading at DRYWALL, FIBERBOARD, PLASTER INTERIORS - home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see AGE of a BUILDING, HOW to DETERMINE - home

Or see NAILS & HARDWARE, AGE

Or see WALL FINISHES INTERIOR

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WOOD LATH for PLASTER or STUCCO at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING INTERIORS

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