What Is Lathing in Construction?
In the world of construction, what lies beneath the surface is often just as important as what’s visible. One such hidden yet crucial process is lathing—a foundational technique that prepares surfaces for finishing materials like plaster or stucco. Whether it’s an interior wall, a ceiling, or an exterior façade, lathing ensures that the final coating adheres properly and remains durable over time.
In this comprehensive guide, we’ll explore what lathing is in construction, its importance, types, installation process, and where it’s commonly used.
🧱 What Is Lathing in Construction?
Lathing is the process of attaching a framework, called lath, to a surface such as a wall or ceiling. This framework provides a mechanical key for materials like plaster, stucco, or fireproof coatings to adhere. The lath can be made of wood, metal, gypsum, or plastic and is secured to the building structure before any finish layer is applied.
The purpose of lathing is to create a strong, stable base that promotes bonding, minimizes cracking, and ensures long-lasting finishes.
🛠️ Why Lathing Is Important in Construction
Lathing might be hidden from view, but its role in the durability and quality of surface finishes is undeniable.
Key Functions of Lathing:
- Supports wet-applied finishes (e.g., plaster, stucco)
- Provides grip for coatings
- Allows shaping over curved or irregular surfaces
- Reinforces walls and ceilings
- Improves fire resistance in assemblies
- Helps control cracking through joint placement
Without proper lathing, finishes can fail prematurely due to poor adhesion, cracking, or detachment.
🏗️ Common Applications of Lathing
Lathing is used in a variety of construction systems. Some of the most common include:
- Interior Plaster Walls and Ceilings
- Especially in older homes or high-end builds using traditional plaster.
- Exterior Stucco Finishes
- Over masonry or wood sheathing, often using metal lath.
- Fireproofing Structural Steel
- Applying fire-rated plasters or coatings over a lath base.
- Soundproofing Assemblies
- Lath can serve as a layer in multi-component acoustic systems.
- Decorative and Curved Features
- Lathing supports shaping plaster into arches, domes, and unique architectural elements.
🔍 Types of Lath Materials Used
| Lath Type | Material | Best For |
|---|---|---|
| Wood Lath | Thin wood strips | Traditional plaster in historic buildings |
| Expanded Metal Lath | Slit & stretched steel | Exterior stucco, fireproofing |
| Woven Wire Lath | Interlaced metal mesh | Uneven or curved surfaces |
| Gypsum Lath | Paper-faced gypsum | Modern veneer plaster walls |
| Paper-Backed Lath | Metal + paper backing | Moisture control behind stucco |
| Plastic (Vinyl) Lath | PVC mesh | High-moisture areas or where corrosion is a concern |
🧰 How Lathing Is Installed
The lathing process must be carefully executed to provide proper support and bonding for the finishing material.
Step-by-Step Lathing Process:
- Surface Preparation
- Install a weather-resistant barrier (WRB) if required.
- Ensure the substrate is clean and solid.
- Lath Attachment
- Secure the lath with galvanized nails, screws, or staples.
- Overlap lath by at least ½ inch at seams and 1 inch at ends.
- Furring
- Create space behind the lath to allow plaster or stucco to “key” through the mesh.
- Accessory Installation
- Add corner beads, control joints, casing beads, and weep screeds as necessary.
- Inspection and Final Prep
- Verify lath is tight, properly overlapped, and fastened according to code.
📦 Benefits of Lathing in Construction
| Benefit | Explanation |
|---|---|
| Superior Adhesion | Enhances grip of wet materials to the surface |
| Structural Reinforcement | Adds rigidity to walls, especially in multi-layered assemblies |
| Crack Prevention | Reduces the risk of surface cracking through proper joint placement |
| Moisture Management | Helps manage water drainage when used with WRB and weep screeds |
| Fire Resistance | Essential in building fire-rated wall systems |
| Versatility | Works on flat, curved, or irregular surfaces |
🧱 Lathing vs. Drywall: What’s the Difference?
| Feature | Lathing + Plaster | Drywall |
|---|---|---|
| Finish | Hard, smooth, long-lasting | Softer, taped seams |
| Installation Time | Slower, multi-step process | Fast and easy |
| Cost | Higher | Lower |
| Durability | Very durable | Moderate |
| Soundproofing | Better when layered | Standard unless modified |
| Curved Surfaces | Easier to shape | Difficult to apply without special framing |
🧠 Modern Relevance of Lathing
While drywall has replaced traditional plaster in most residential settings, lathing remains essential in many construction sectors:
- High-end custom homes using veneer or traditional plaster
- Commercial buildings requiring exterior stucco finishes
- Fireproof assemblies in multi-story or industrial buildings
- Restoration of historical architecture
Lathing also plays a critical role in EIFS (Exterior Insulation and Finish Systems), where it supports base coats over insulation panels.
✅ Best Practices in Lathing
- Always use corrosion-resistant fasteners in wet or outdoor conditions.
- Overlap metal lath to avoid cracks at seams.
- Install control joints at appropriate intervals to allow movement.
- Use weep screeds to allow moisture to escape behind exterior stucco.
- Consult local building codes for lath type and fastening requirements.
❓FAQs About Lathing in Construction
1. What does lathing mean in construction?
Lathing is the installation of a mesh-like base (lath) on walls or ceilings to support plaster, stucco, or similar coatings.
2. Why is lathing important?
It provides a rough surface for finishing materials to adhere to, helps prevent cracking, and reinforces the structural layer of walls and ceilings.
3. What materials are used for lath?
Common lath materials include wood, metal mesh, gypsum boards, and plastic or vinyl mesh.
4. Is lathing still used in modern construction?
Yes. It’s essential for exterior stucco, fireproofing, veneer plaster, and historical restoration projects.
5. How is lath installed?
Lath is secured to framing with fasteners, overlapped for continuity, and supported with accessories like control joints and corner beads.
6. What is expanded metal lath?
A type of lath made by slitting and stretching metal sheets to form a diamond mesh, used primarily for stucco and fireproofing.
7. What is the difference between lathing and drywall?
Lathing supports wet finishes like plaster, while drywall is a ready-to-finish sheet material applied directly to framing.
8. What are control joints in lathing?
These joints allow for expansion and contraction, reducing the risk of cracking in the finished surface.
9. Is lathing required by code?
In many cases, yes—especially for stucco and fire-rated assemblies. Local building codes often dictate lath type, spacing, and fasteners.
10. Can lathing be used over concrete?
Yes, with the use of appropriate fasteners or adhesives, metal lath can be applied to concrete for stucco or veneer stone applications.
Conclusion
Lathing may be a hidden part of the construction process, but it plays a critical role in the strength, durability, and beauty of finished surfaces. Whether you’re applying exterior stucco or crafting a decorative plaster interior, proper lathing ensures that the finish adheres well and lasts for years. Understanding its types, applications, and techniques helps builders and designers create long-lasting, high-quality construction results.
