Treehouse Fasteners Explained: TABs vs. LAGs and How to Use Them
A treehouse attachment bolt (TAB) and a treehouse lag bolt are two different types of fasteners commonly used in treehouse construction today. Let's explore how they differ and when to use each:
TREEHOUSE ATTACHMENT BOLT (TAB)
A Treehouse Attachment Bolt, also known as a TAB or a Garnier limb, is a specialized type of fastener designed for treehouse installations. It consists of a long, threaded steel rod with a large, round, or square plate at one end. The threaded portion is inserted through a pre-drilled hole in the tree trunk, while the plate rests against the outer surface of the tree. The bolt is secured in place by tightening a nut on the threaded end. TABs are typically installed higher up on the trunk, away from the ground.
When to use TABs:
TABs are used when constructing treehouses that require a high load-bearing capacity. They provide exceptional strength and stability, making them suitable for larger or multi-level treehouses. TABs are also preferred in situations where the tree is expected to grow, as they allow for some flexibility and movement.
TREEHOUSE LAG BOLT:
A Treehouse Lag Bolt, also known as a lag screw or lag bolt, is a heavy-duty screw with a coarse thread and a pointed tip. Unlike the TAB, the lag bolt does not have a large plate attached to it. Instead, it relies on its thread pattern and self-drilling capabilities to secure the treehouse components. Lag bolts are typically shorter than TABs and are installed at a shallower depth.
When to use lag bolts:
Lag bolts are used for lighter or smaller treehouse structures that don't require as much load-bearing capacity. They are suitable for attaching beams, joists, and other framing components to the tree. Lag bolts are easier and quicker to install compared to TABs since they don't require the drilling of a large hole. However, they may not provide the same level of long-term stability as TABs.
Does your treehouse need TABS or Lags?
The simple answer: it depends on the size of your treehouse.
For Treehouses 75 square feet and under:
Our MINI treehouse hardware kits previously used Lag Bolts, and (depending on the shape of the structure you choose) will generally work for treehouses up to 75 square feet in size
For Treehouses larger than 75 square feet:
Our SMALL Treehouse Hardware Kits and STANDARD Treehouse Hardware Kits use TABs and (depending on the shape of the structure you choose) will generally be suited to treehouses over 75 square feet in size
NOTE: these recommendations are based on the quality and weight-bearing capacity of our TABS and Lag Bolts, which we have tested vigorously. Other products on the market may not match our quality and load capacity. Individual needs may differ and there may be exceptions to this recommendation. We recommend factoring in the live load and consulting an engineer as needed.
We make it easy with our Treehouse Building Plans & matching Hardware Kits
We've carefully developed our easy-to-use system of Treehouse Hardware Kits that combine with our Treehouse Construction Plans to construct the treehouse of your chosen shape and size (just add lumber and you're all set to master a DIY Treehouse project!). Our system of Plans and Kits makes the choice between TABs or lags that much easier- with a hardware kit tailored to the size of the treehouse you intend to build.
Introducing our latest innovation in small structure tree fasteners: CoreTAB™ Treehouse Attachment Bolt exclusive to Treehouse Supplies
When it comes to building in trees, fasteners aren’t just hardware—they’re the foundation of the entire structure. Unlike conventional framing, treehouse construction demands solutions that can handle dynamic loads, seasonal movement, and the long-term health of a living support system. That’s why purpose-built hardware is essential. Standard lag bolts and off-the-shelf fasteners often fall short under the unique stresses of tree-supported builds, leading to compromised stability or unnecessary damage to the tree itself.
Until 2026, we have offered Treehouse Lag Bolts for structures under 75 square feet, and applied TABS for structures over 75 square Feet.
Our latest innovation is a small structure TAB that functions perfectly for treehouses under 100 square feet. Our CoreTAB is also the new standard for our mini treehouse hardware kits, replacing Lag Bolts.
Designed specifically for professional-grade treehouse construction, the new CoreTAB™ - 1.75" x 15" Treehouse Attachment Bolt is engineered to provide you with peace of mind. With a 1.75" diameter stem, it offers greater wood compression than a standard lag bolt, ensuring a secure and stable connection to live trees. The wood threads are specifically designed for a firm grip, and its 1.25" diameter perch makes it compatible with all our standard brackets.
Ideal for supporting structures up to 100 square feet, the CoreTAB™ is perfect for building a backyard treehouse that your kids will love. Just like our original bolts, the CoreTAB™ is compatible with all our standard treehouse brackets, allowing for versatile support of treehouses of various sizes, shapes, and heights. All our bolts and brackets are designed to accommodate tree movement and growth, ensuring both the safety of your treehouse and the health of your trees.
AN EASY GUIDE TO TREEHOUSE FASTENER SELECTION
At a glance, a treehouse lag bolt and a Treehouse Attachment Bolt (TAB) might seem similar—they both anchor your structure to a tree—but they serve very different roles in terms of strength, performance, and how they interact with the tree over time.
A treehouse lag bolt is essentially a heavy-duty version of a standard lag screw. It threads directly into the tree and can handle moderate loads, making it suitable for lighter-duty applications like small platforms, railings, or secondary supports. However, lag bolts rely heavily on the shear strength of the wood fibers around the threads. Over time, as the tree moves, grows, and responds to weather, those fibers can compress or degrade, reducing holding power. Lag bolts also tend to concentrate stress in a smaller area of the tree, which can lead to more damage if overloaded.
A Treehouse Attachment Bolt (TAB) — like the CoreTAB from Treehouse Supplies — is purpose-built specifically for structural treehouse construction. It’s significantly larger in diameter and incorporates a thick, unthreaded shaft (called the shank) along with a wide shoulder or “boss” that supports brackets and beams away from the tree. This design does a few critical things:
- it distributes loads more evenly
- reduces stress on the tree
- allows the structure to “float” slightly as the tree moves.
TABs are engineered to handle major structural loads — often thousands of pounds — making them the go-to choice for primary support points in professional builds.
The Benefits of Powder Coating:
TABs are available with Powder Coating. Powder-coated bolts offer superior protection against corrosion, scratches, and fading. Non powder-coated bolts are more cost-effective but lack the same level of protection and aesthetic customization.
The choice between the two depends on your budget, desired lifespan, and visual preferences for your treehouse.
This is what uncoated bolts and brackets look like over time - they are much more susceptible to rust and will require updating as the metal corrodes over time.
Uncoated treehouse hardware from a competitor brand, significantly rusted and poorly weathered over time
So - TABS or Lags?
To sum up, TABs are heavy-duty, large-scale fasteners designed for high-load applications and long-term stability. They are ideal for larger treehouses or situations where the tree is expected to grow. Lag bolts are more suitable for smaller or lighter treehouses and provide a simpler installation process.
In practical terms, the difference comes down to scale and responsibility. Lag bolts are best for smaller, non-critical connections, while TABs are designed for the main load-bearing elements of a treehouse. If you’re building something that needs to be safe, long-lasting, and tree-friendly, TABs aren’t just an upgrade—they’re the standard.
The choice between TABs and lag bolts depends on your treehouse project's specific requirements and the structure's load-bearing needs. Still not sure what will work for you? Contact Us, we'd be happy to help!