Structural steel plates, particularly corner brackets bent at 90° angles and pre-drilled with holes, can play a useful role in reinforcing and supporting wood framing elements. Today, we’ll take a look at a particular installation that has been built well to last for many years, longer than the typical fence installation. We’ll look at this in two parts total, and today we begin with part one.
These brackets are designed to provide additional strength and stability to the joints and connections between various wooden components, such as studs, joists, and beams. These joints can be a weak point in the assembly of framed wood materials. It’s for this same reason that the best practices for deck construction and building include the use of several different types of structural steel connectors which we’ve talked about extensively in previous articles on our website. Here though in the construction of a relatively simple fence, these connectors become even more useful because unlike a deck, this type of fence system has fewer structural members in a framework that is spread apart farther than a typical elevated deck.
The picture below shows a heavy duty wood fence built between the walking path through a neighborhood and the private property against the roadside. This pathway isn’t made just for walking because people also frequent the pathway on their daily bike rides and or bike commute through the neighborhood. For this reason, this fence is built with a higher degree of structural strength. It’s built with larger pieces of wood and 6×6 post instead of the typical 4×4 post found in most low height fences.
The corner brackets we described, for decks, are typically manufactured from galvanized steel. These are similar but are actually a lower strength galvanization with a protective coating applied in addition to the galvanization. They are fabricated with a right-angled bend, to fit over the corners of the joined wood framing members of the fence. The pre-drilled holes, approximately eight per side, are placed, almost like a gusset, Inna spaced pattern, to accommodate external hex head screws, which are specifically designed for fastening metal to wood.
Hex head screws, often referred to as “lag screws” or “hex lag bolts,” are particularly well-suited for this application due to their heavy build, compared to regular deck screws, and ability to withstand high torque during installation. The hexagonal head provides a secure grip for tools, allowing for the application of significant force during tightening, ensuring a tight and secure connection between the steel bracket and the wood framing.
Unlike a typical fence between a walkway and a private property, this fence is not clad for privacy, instead it has only three long horizontal rail style boards (without an intermediary vertical spacer board and it looks better without it but uts weaker) and therefore has a lesser degree of overall strength or connectivity in the greater assembly of the fence. A typical fence panel, built for privacy, may have various vertical or horizontal boards laid together or a joint side-by-side and fastened on the ends and with intermediary perpendicular boards. That framework provides an increased amount of overall strength, ceteris paribus, meaning that with the same size boards the strength will be greater, in comparison.
Here though without multiple additional perpendicular boards overlapping the framework of the fence, these steel brackets help tie the individual horizontal members to the larger post in a stronger joint and connection.
One notable feature of the external hex head screws, shown here, is a flange-like shape of the screw head at the bottom of the head, where the screw head presses against the bracket. This flange serves as an additional bearing surface, distributing the clamping force over a larger area and reducing the risk of the screw head being forced into deformation of the steel plate or reaming the screwhole. This design enhances the overall holding power and longevity of the connection as grains shift over type because without reaming or stripping or boring, each screw head remains indiviually engaged in the wood grain.
By installing these steel corner brackets at the junctions of wood framing elements, similar to other smaller galvanized steel brackets we have seen in past blog articles, at the corners of walls, floor joists, and roof trusses, the overall structural integrity and load-bearing capacity of the framing system is increased. The brackets act as reinforcements, transferring loads between the connected members and providing additional resistance against lateral forces, such as wind or seismic activity.
As well, the use of these steel brackets can help mitigate potential and common issues from wood shrinkage, warping, or settling over time. The rigid metal brackets maintain and hold the specific angles and connections, preventing the wood framing from shifting or separating, which would compromise the structure’s stability, require increased rework and maintenance and generally degrade the overall longevity of the fence, while increasing lifecycle costs.
When you look at the top of the post, here in the picture below, you can also see other details of better or best practices in exterior fence construction. The top of this fence is cut at a chamfer or angle to allow water to run down the top of the post without pooling at a flat cut top. Different types of both ornamental and functional caps are available in many cases, but this particular simple aesthetic works well from a visual perspective and is almost as effective as a metal or impermeable cap as the cut angle increases the resistance to water infiltration at the end grain at the top of the post.
The top of a post, where the end grain is exposed in a horizontal position, is more susceptible to water infiltration than cross-grains in the same position due to the unique cellular structure and orientation of wood fibers. Wood is composed of elongated cells or fibers that run parallel to the tree’s trunk or stem. These fibers act like tiny straws or capillary tubes, with the ability to draw and transport moisture through the wood’s structure by capillary action.
When the end grain is exposed, the open ends of these fibers are directly exposed to water. This allows water molecules to easily enter and travel along the length of the fibers, almost like water being drawn up through a straw. The capillary action, combined with the natural tendency of water molecules to bond together, facilitates the wicking of moisture deep into the wood’s structure. In contrast, when the cross-grain is exposed, the water molecules encounter the sides of the wood fibers, which are less permeable and offer greater resistance to water infiltration. The cross-grain exposure limits the direct access of water to the open ends of the fibers, reducing the effectiveness of capillary action.
This difference in water transport mechanisms makes the end grain significantly more vulnerable to moisture absorption and potential water damage. Over time, prolonged exposure to water can lead to swelling, cracking, and even rot or decay in the end grain areas, compromising the structural integrity of the wood, so even though a cap is better, the chamfered or angled cut helps, at the top of the post.
These brackets change (and improve) the fastener orientation and wood grain direction, in relation to the fasteners at least at one of the joined boards, when joining boards at 90° angles. This helps the strength and integrity of the connection, considerably.
When boards are joined at a butt joint or even with a mitered 90° angle, if the fastener (such as a nail or screw) is driven through the cross-grain of one board into the end grain of the other, the connection may not be as strong as expected. The end grain of wood is inherently weaker and more susceptible to splitting or cracking under stress.
Use a contractor who understands and cares about doing things right. Always, feel free to reach out to us here at Dupont Decks and Patios. We are happy to help with almost all steps of the deck building and design process. Let us know about your ideas and talk to us if you have questions about possibilities . You can call us at (202) 774-9128. You can find us online at https://dupontdeckspatiosdc.com and you can email us there as well at https://dupontdeckspatiosdc.com/contact-us
