Types of Lath: Exploring Wood, Metal, and Gypsum


Understanding the different types of lath used in construction is essential for anyone involved in building or renovating. Wood, metal, and gypsum lath each have unique qualities and applications. Wood lath has been utilized for over 400 years, primarily for supporting plaster on walls and ceilings.

Metal lath, which includes various types like expanded metal and wire lath, emerged in the late 19th century. It offers a more durable and fire-resistant option compared to wood. Gypsum lath, also known as rock lath or plasterboard lath, became common in the early 20th century. This type of lath provides a smooth and stable surface for plastering, enhancing both durability and ease of installation.

These materials each serve specific purposes in building projects, from structural support to aesthetics. Explore how each type of lath can be applied to improve the quality and longevity of your construction endeavors. For more detailed information, you can also refer to wood lath’s historical use and the development of metal lath.

Overview of Lath in Construction

Lath plays a crucial role in construction, providing foundational support for various types of wall and ceiling finishes. It has evolved significantly over time, with different materials offering distinct advantages for specific applications.

Historical Context

Traditionally, lath was made from wood and was extensively used in interior wall construction. Wooden strips were nailed to wall studs, forming a base for plaster. This method, while effective, was labor-intensive and required skilled workmanship.

In the early 20th century, metal lath started to gain popularity. This new material was more durable and less prone to warping or decay. By the mid-1900s, metal lath had largely replaced wood in many areas due to its strength and versatility in supporting plaster.

Gypsum lath, also known as rock lath, emerged during the same period. It provided an even quicker and easier installation process. Gypsum lath consists of pre-manufactured boards that could be nailed directly to the studs, significantly reducing the time needed for wall construction.

Lath Materials

Wood Lath:
Even though wood lath is less common today, it is still used in some restoration projects. These narrow wood strips are traditionally about 1/4 inch thick and 1 inch wide. They require a high level of craftsmanship.

Metal Lath:
Metal lath, often made from steel, is used extensively in modern construction. It is available in various forms, such as diamond mesh and expanded metal lath. It provides a strong base for plaster, tiles, and other finishes. Metal lath sheets are manufactured in specific lengths to fit common framing member spacing, ensuring a secure fit on walls and ceilings.

Gypsum Lath:
Gypsum lath, made from gypsum plaster, is commonly used in plasterboard applications. Rock lath panels are typically 16 inches wide and 48 inches long, featuring a layer of gypsum with a special paper backing. This type is favored in modern drywall construction for its speed of installation and smooth finish.

Types of Lath

Types of Lath

Lath is an essential component in lath and plaster walls, serving as a supportive framework. There are three main types: wood lath, metal lath, and gypsum lath. Each type has its own unique properties and uses in construction.

Wood Lath

Wood lath consists of narrow strips of wood, traditionally used as a base for plaster. These strips are typically about 1/4-inch thick and 1-1/2 inches wide. Wood lath has been utilized for hundreds of years and is known for its ability to hold plaster securely.

There are different types of wood lath, including riven, hand-split, and sawn lath. Riven lath is hand-split from larger pieces of wood, providing a rough surface that grips plaster well. Hand-split lath is often found in older buildings. Sawn lath is smoother and cut by machines.

Wood lath has been largely replaced by more modern materials, but it can still be found in historic buildings. It provides flexibility and strength, but it may be prone to rot and insect damage over time.

Metal Lath

Metal lath is commonly used in modern construction for its durability and strength. It consists of expanded metal sheets that help the plaster adhere. These sheets are typically made of galvanized steel to prevent rust.

Diamond mesh lath and ribbed lath are popular forms of metal lath. Diamond mesh lath provides a good base for plaster, while ribbed lath includes ribs for added strength and support. This type of lath is often used in areas that require extra reinforcement, such as ceilings.

Metal lath offers excellent support and is less susceptible to moisture damage compared to wood lath. It’s commonly used in areas prone to dampness or where additional structural support is needed.

Gypsum Lath

Gypsum lath, also known as rock lath, is a type of sheet material used as a base for plaster. It consists of gypsum plasterboard with a special paper facing. The gypsum core provides rigidity, while the paper facing helps the plaster adhere.

Gypsum lath became popular in the mid-20th century as a faster and more efficient alternative to traditional wood lath. It is typically available in sheets, making it quicker to install than individual wood strips.

This type of lath is particularly effective in fire-resistant construction. It offers a smooth surface for plaster and is less prone to cracking compared to wood lath. Gypsum lath is widely used in both residential and commercial buildings due to its ease of installation and durability.

Wood Lath

Wood lath has been a fundamental component in wall and ceiling construction for centuries. It offers unique properties and has a specific installation process that lends both advantages and some challenges in its use.

Properties of Wood Lath

Wood lath consists of thin, narrow strips of wood, typically straight-grained and free of knots. These strips, usually around 1-inch wide and 4 feet long, are nailed to wall studs or ceiling joists. The spacing between each strip allows plaster to key into the gaps, providing a secure bond.

Historically, hand-split wooden lath was common. Modern lath, however, is often machine-cut for uniformity. Despite advancements, wooden lath remains a favored material in the restoration of historical buildings.

Installation and Use

The installation of wood lath begins by nailing the strips horizontally across stud or joist structures. This creates a supportive base for the plaster. Typically, three layers of plaster are applied. The first layer forms a strong bond with the wood, filling the gaps. The second layer smooths out any unevenness, and the final layer creates a hard, smooth finish suitable for painting or wallpaper.

Due to the labor-intensive nature of the process, wood lath is mostly found in older homes and buildings. Modern alternatives such as drywall have largely replaced it for new construction.

Advantages and Challenges

Wood lath provides robust support for plaster, which can last for decades if well-maintained. It also offers excellent sound insulation and a certain historical charm. Wooden lath can be used to restore buildings to their original condition, maintaining their authenticity.

Challenges include the labor-intensive installation process and the potential for cracking over time as wood expands and contracts with changes in humidity. Plaster repair on wood lath can be complex and costly. Insects and moisture can also damage the wood, leading to additional maintenance issues. Despite these challenges, the historical and aesthetic value often outweigh these concerns in heritage buildings.

Metal Lath

Metal lath serves as a crucial support structure for plaster and stucco applications, providing durability and strength. This section covers different types of metal lath, including their specific features and installation methods.

Expanded Metal Lath

Expanded metal lath is often made from sheets of galvanized steel that are slit and stretched to form diamond-shaped openings. These openings allow plaster to key into the lath, creating a strong bond and smooth surface.

The galvanized coating enhances corrosion resistance, making it suitable for exterior stucco systems. Expanded metal lath has been widely used in construction for over 50 years due to its fire resistance and structural integrity. Its open design also helps in reinforcing the overall wall structure, making it less prone to cracking.

Wire Mesh Lath

Wire mesh lath consists of a grid of welded wires, creating a similar bonding surface for plaster. This type of lath is also galvanized to resist rust and corrosion. Wire mesh lath is particularly effective for curved surfaces or areas requiring additional reinforcement, such as corners or arches.

Due to its flexibility, wire mesh lath is often used in more complex or customized construction projects. It is less common than expanded metal lath but provides comparable strength and durability. The mesh allows the plaster to grip securely, ensuring a lasting finish.

Installation Techniques

Proper installation of metal lath is vital for successful plaster or stucco application. The lath is typically fastened over the stud plane using staples, nails, or wafer head lath screws. It must be securely attached to prevent movement and ensure a seamless plaster surface.

Installers must ensure that each sheet of lath overlaps correctly and is tightly secured to avoid gaps. The edges should be well-fastened, and any protruding wires or sharp edges should be trimmed. This careful installation helps to create a uniform and stable base.

Using metal lath correctly can significantly impact the durability and appearance of plaster or stucco finishes. Proper attachment and tensioning are essential for a smooth, crack-free finish. By following these techniques, builders can achieve a high-quality, professional result.

Gypsum Lath

Gypsum lath, also known as rock lath or plasterboard, provides a sturdy base for plaster finishes. It consists of gypsum plaster sandwiched between two layers of felt paper, offering several benefits in construction.

Characteristics of Gypsum Lath

Gypsum lath is commonly used in building interiors. It comes in large panels, typically 16 inches by 48 inches. These panels are nailed directly to the studs, creating a flat surface for the plaster.

One of its key features is its moisture resistance. Gypsum naturally repels water, making it less likely to warp or mold compared to wood lath. This quality is particularly useful in humid environments.

The gypsum plaster itself is lightweight and easy to handle, which speeds up the installation process. Once installed, the material supports plaster finishes, providing a durable and smooth end product. It also adds some insulation to walls, enhancing energy efficiency slightly.

Comparing Gypsum Panels and Boards

Gypsum lath is different from other gypsum-based products like gypsum board or drywall. While gypsum board serves as a finishing surface, gypsum lath is designed to be a base for plaster.

A key difference lies in their construction. Gypsum lath features perforations or a rough texture on one side to help the plaster adhere better. In contrast, gypsum board has a smooth surface ready for painting or wallpaper.

Gypsum panels are also thinner and more flexible, which allows for easier handling and cutting during installation. This flexibility can be beneficial when working with irregular wall shapes.

Although both materials are made from gypsum, which makes them resistant to fire, they serve distinct roles in the construction process. Gypsum lath is for plaster bases, while gypsum board is often the final wall surface.

For more detailed information, you can read about the types of gypsum lath used in construction.

Lath and Plaster Techniques

Lath and plaster techniques involve several layers and steps to ensure a smooth, durable finish. These steps include creating keys with a scratch coat, applying a brown coat, and finishing with a top coat. Specialized plaster types can also be used for specific needs.

Keys and Scratch Coat

Keys are fundamental in lath and plaster walls. When plaster is pushed through the gaps in the lath, it forms “plaster ears,” or keys, which lock the plaster onto the lath. This mechanical bond is crucial for the wall’s stability.

The scratch coat is the first layer of plaster applied. It contains sand and helps create a rough surface for the next layers to bond. Workers use a comb-like tool to scratch lines into the wet plaster, improving the bond between coats. This layer typically contains more sand than subsequent layers to enhance its bonding properties.

Brown Coat and Finish Coat

The brown coat is the second plaster layer applied over the scratch coat. It smoothes out imperfections and prepares the surface for the final coat. This layer is typically thicker than the scratch coat and must be troweled evenly for the best results.

After the brown coat dries, the finish coat is applied. This final layer is a thin, smooth coat designed to hide any remaining imperfections and provide a polished surface. The finish coat often contains finer sand and may also include lime or other materials to improve workability and finish quality. The entire process requires skill to ensure each layer bonds properly and dries evenly.

Specialized Plaster Types

Different types of plaster can be used depending on the project’s needs. Traditional lime plaster is common for historic renovations due to its compatibility with older buildings. Gypsum plaster is more popular for modern applications because it dries faster and is easier to work with.

For areas with high moisture, waterproof or moisture-resistant plasters can be used. These specialized plasters help prevent mold and damage from water exposure. Another specialized type is Venetian plaster, known for its polished, marble-like finish. These choices allow flexibility in design and function, making lath and plaster systems versatile for various settings.

Application in Construction

Application in Construction

Lath is a crucial component in construction, offering structural support and enhancing insulation and soundproofing. It also plays a role in the durability and ease of repairing walls and ceilings.

Walls and Ceilings

Lath is widely used as a base for plaster on walls and ceilings. There are several materials for lath, including wood, metal, and gypsum. Wood lath has been a staple in construction for over 400 years. Metal lath, often made of expanded metal, is praised for its strength and is commonly used in modern construction. Gypsum lath, also known as rock lath, became popular in the mid-20th century as a cost-effective alternative. These materials provide the necessary framework to apply plaster, which adheres to the lath and creates a smooth, durable finish on walls and ceilings.

Insulation and Soundproofing

Lath and plaster systems offer notable benefits in insulation and soundproofing. The combined thickness of the lath and plaster layers provides better insulation compared to drywall, helping to keep interiors warm in winter and cool in summer. This method also significantly aids in soundproofing. The dense nature of plaster combined with the multiple layers of wood or metal lath can effectively dampen sound transmission through walls and ceilings. This makes lath and plaster an excellent choice for residential and commercial buildings where noise reduction is important.

Durability and Repair

The durability of lath and plaster walls is one of their strongest attributes. These walls are resistant to impacts and can last many decades with proper maintenance. When it comes to repairs, both wood and metal lath systems have their benefits. Plaster can be patched without needing to replace entire sections of the wall. For metal lath, which is often used in exterior applications, the material resists rust and corrosion, adding to its longevity. The key to a successful repair is to properly prepare and match the existing plaster material, ensuring a seamless and durable fix.

Advancements and Technology

Recent advancements in lath technology have focused on improving material quality, performance, and sustainability while complying with modern building codes and regulations. This section explores these innovations and their impact on the construction industry.

Modern Materials and Methods

Technology in lath production has introduced stronger and more durable materials. Expanded metal lath, for instance, now features advanced coatings that resist corrosion and increase lifespan. Ingenious designs in metal lath improve the bond with plaster, enhancing structural integrity in building interiors.

Gypsum lath, also known as rock lath, has evolved to offer better fire resistance and moisture control. Modern gypsum boards often incorporate additives that protect against mold and mildew, enhancing their performance. These materials are widely used across the United States and Canada, providing reliable solutions for both residential and commercial projects.

Performance and Sustainability

Contemporary lath products are designed with performance and sustainability in mind. Metal lath, for example, is often manufactured using recycled materials, reducing environmental impact. These laths offer superior strength, distributing plaster evenly and maintaining structural stability over time.

Gypsum lath’s improved formulations reduce waste and promote efficient resource use. The advancement in gypsum technology ensures materials meet the demands of modern construction while minimizing ecological footprints. In the United Kingdom, stringent standards push for sustainable practices, influencing global trends in lath manufacturing and use.

Legal and Code Considerations

Building codes and regulations have significantly influenced advancements in lath technology. The International Building Code (IBC) and local codes in the United States demand high standards for fire safety and structural performance. Expanded metal lath must meet specific criteria for bonding strength and durability to comply with these regulations.

In Canada, the National Building Code similarly enforces strict guidelines for lath and plaster systems. These legal considerations ensure that all materials used are safe, reliable, and perform well under various conditions. The adherence to these codes not only ensures safety but also fosters innovation as manufacturers strive to meet and exceed regulatory requirements.

Cost and Labor Factors

Understanding the cost and labor involved in installing lath is crucial for planning and budgeting. This section covers the material costs for wood, metal, and gypsum lath, as well as the labor and installation expenses for each type.

Materials Cost Analysis

The cost of materials for installing gypsum lath averages around $.78 per square foot, with a range between $0.53 to $1.04. For a 500 square foot project, this totals approximately $1,211.65, but prices can vary based on quality and local market rates.

Wood lath is another option, typically used in older buildings. The cost for wood lath ranges widely depending on its quality and availability, but the market trends show it is often slightly higher than gypsum lath. Metal lath is usually the most expensive, driven by its durability and use in high-stress areas. Detailed pricing is essential as material costs can significantly impact the overall budget.

Labor and Installation Costs

Labor costs vary for different types of lath. For gypsum lath, labor alone ranges from $2.42 per square foot, with total prices increasing with complex site conditions. Installers must secure the gypsum to structural framing and ensure it does not twist or move, adding to the labor intensity.

The installation of wood lath involves precise fitting and securing, typically costing more in labor due to the skill required. Metal lath installation is labor-intensive, often involving cutting and fitting around irregular surfaces, resulting in higher rates. Plaster repair methods for existing lath can also influence labor costs, especially if extensive preparation is needed beforehand.


Wood, metal, and gypsum lath each play distinct roles in construction. Wood lath has a long history and is still valued for its traditional charm. It consists of narrow strips of wood nailed horizontally.

Metal lath offers greater durability. There are various types, such as diamond mesh and expanded metal lath. It prevents cracks in plaster and is ideal for modern construction.

Gypsum lath, also known as rock lath, provides a smooth surface. It is commonly used as a base for plaster, helping in faster installation and better fire resistance.

Each type has its specific advantages. Wood is chosen for heritage projects, metal for robustness, and gypsum for efficiency. Understanding these materials’ properties can guide effective use in construction.

Key Points:

  • Wood Lath: Traditional, used for historic restorations.
  • Metal Lath: Durable, prevents plaster cracks.
  • Gypsum Lath: Smooth, fast installation, fire-resistant.

Careful selection of lath type can enhance the quality and longevity of construction projects.

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