What are plywood clips and what are they used for? These are usually pieces of small metal that can either be smooth or galvanized. They’re normally placed between two adjacent wood sheathing panels at a location between supporting joists/trusses and/or rafters in order to provide support to panel edges.
The thickness of the plywood clips is normally between eighteen and twenty gauge and 0.040 inches. Typically, plywood clips are used to reduce the spacing of the framing members by improving the load distribution and increasing the effective stiffness of the roof and floor deck. Also, plywood clips provide the suggested spacing between adjoining panel edges. This allows room for panel expansion if the panels end up getting wet during construction.
Why Plywood Clips
Also referred to as H-clips and panel edge clips, plywood clips are small metal brackets that are placed between the unsupported edges of plywood sheathing so it can effectively reduce the support spacing. It helps stiffen the plywood. These clips are inserted over the edges of the adjacent plywood panels to help reduce deflection of the panel edges between the framing members. It’s usually used for roof sheathing. The plywood clips are inserted by hand and are done in conjunction with the installation of the sheathing.
Plywood Clips and Building Code Standards
One of the questions often asked about plywood clips is if they’re required by the building code when doing roof sheathing. Technically speaking, they’re not required but they are recommended. Most builders install them anyway. The International Residential Code (IRC) and the Residential Edition of the Florida Building Code (FBC), both refer to Table R503.2.1.1(1) of the APA Engineered Wood Construction Guide for specs. Usually referred to as H-clips, plywood clips are referred to in the APA Guide as edge support.
Whether or not plywood clips are standard is a tricky topic. In 2006, the IRC did make it a requirement to use the H-shaped clips during construction. However, not every jurisdiction complies with these regulations. There are some cities within a certain state that will comply while others won’t. Another issue is homes that were built prior to the code requirement of plywood clips.
Because of this, these houses are deemed as violators of the IRC code. According to InterNACHI, the standards of practice by its home inspectors are limited to system defects and safety issues. This means it’s not necessary for home inspectors to determine whether or not the lack of H-shaped plywood clips would be considered a building code violation.
Nowadays, among the most common roof sheathing practices, the construction industry uses a half-inch nominal sheathing over trusses or rafters at twenty-four inches on center doesn’t require plywood clips. The APA table has a span rating for sheathing installed with or without the clips. A low slope roof that’s below 2/12 pitch at the same span is an exception where a plywood clip is specified. These are necessary for other wood panel thickness and span combinations. One or two plywood clips often allow a longer span between roof trusses and rafters.
According to the APA, when support spacing exceeds the maximum length of an unsupported edge, there is a need for plywood clips to provide sufficient blocking, tongue-and-groove edges, and other support. Some types of panel clips also assure proper panel spacing. It should be one plywood clip per span under forty-eight inches. Anything more than this requires at least two plywood clips.
When plywood clips are missing, you will notice this while walking on a roof. You will find the surface more flexible as you step on what is an unsupported plywood edge. Plywood clips are essential to reduce any buckling that may occur with those edges as time progresses. Even though these clips are not required by the building code they should still be used.
Since plywood clips are not load rated, there is no requirement for them to be subject to code approval. However, based on gravity load requirements, there are building codes that often require plywood clips or something similar to serve as support for the panel edges. Plywood clips are also great as an alternative to solid lumber blocking and panel edges that are tongue and grooved in many applications.
The panel edge support requirements under uniform gravity loads are provided in specific building codes. Usually, when referring to building code requirements for construction-related projects, there will be tabled information laid out, much like what’s seen on sites like PFS-TECO.
There have been occasions where the lack of H-shaped plywood clips has counted as a building code defect. Regardless of the situation, the home inspector would merely make a note about it as part of their reporting process. Without seeing the construction plans of a building, the inspectors have no way of knowing whether or not plywood clips were actually used in those plans. With this being said, their ability to determine whether or not any clips were used is restricted.
How to Use Plywood Clips
Install the plywood before adding the H-shaped plywood clips. Make sure to install a full horizontal row of plywood sheathing. As you do this, make sure you follow the best practices and code standards when installing your plywood. By doing this, you’re ensuring your installation is done properly. Ideally, you want the roofing project done properly, free of error.
Now it’s time to position the plywood clips. Position each clip on the upper or top horizontal edge of the panel of wood, then slide the H-shaped fins right over the plywood. You want to connect the section in the middle against the edge of the plywood. As an example, a sixteen-inch centered framing needs to have a clip in the middle between each of the perpendicular framing members. For a twenty-four-inch centered framing, you’d need to position a pair of clips equidistant from each other between the joists and rafters. You should have these about eight inches apart.
After the first plywood row has been installed with the clips in place, proceed to the next row and do the exact same thing. You want to position the next sheet by sliding the bottom edge into the channel of the already installed plywood clips. All you need to do at this point is secure the plywood panel to the framing. Keep going until all the plywood panels and plywood clips are in place and secured.
Not Just for Roofs
Although roofing projects rely heavily on plywood clips, this isn’t the only construction project that makes good use of the H-shaped product. They also work great for slanted walls and ramp-style flooring projects. The H-shaped plywood clips give support to the plywood as there will be reduced flexing, especially when it comes to the edges. As ridiculous as this may sound, in the long run, you will have slanted walls that will last without structural issues developing over time.
You will also have ramp-style floors that won’t also maintain their structural integrity. If the place of business or residence requires a ramp in order to better accommodate individuals with special mobility needs. The reason this is brought up came from two golf course facilities that installed rather long and steep ramps. These were built during the same summer where one used the plywood clips and the other didn’t. Both used plywood sheets before finishing their respective projects.
In less than a decade’s time, the ramp built without the plywood clips had the edges between panels gradually become saggy and difficult to navigate for people using wheelchairs. As for the ramp built with the plywood clips, there haven’t been any issues at all. The other golf course has since replaced the ramp as it started to become a safety issue. When looking at it from this point of view, imagine how much money the first golf course could have saved if they went with the plywood clips as the other one did.
Calculating How Many Plywood Clips Needed per Sheet of Plywood
Roofing is regarded as a complicated project. Usually, professionals are hired to do the job because they generally know what they’re doing. Between the extensive training they receive, plus the number of projects they’ve done, the most experienced roofers treat roofing projects like a piece of cake. When it comes to using plywood sheathing for roofing purposes, the need for H-shaped plywood clips is highly recommended. There should be one plywood clip for each rafter bay or cavity for each sheet of plywood you work with.
When it comes to your roofing project, you first need to figure out how many plywood panels you’re going to need. From there, determine how many rafter bays or cavities you’ll need. Based on those answers, you only need one plywood clip per rafter bay or cavity. So, for example, a sixteen-inch O.C. rafter is using an eight-foot-long plywood sheet. This means you will need six clips on each long edge and twelve clips on both long edges.
As pricey as it may sound, the use of plywood clips increases the panel stiffness. The benefits of the H-shaped clips allow a better distribution of weight between each adjacent panel. When the edges are made stiffer, as a result, the panels are far less likely to experience any structural defects. This is especially true when subjected to loads that are heavier near the edges. When the panels are very thin, like 3/8 inches, stiffening the boards with plywood clips, takes away the threat of bowing. Bowing typically happens when heavier weight compromises the edges.
When plywood clips are used, this helps lower the cost of construction as there will be a reduction in the number of materials needed. Builders using plywood clips will require fewer rafters in order to complete a project as the distance between the rafters is now increased. Furthermore, it allows the builder to use thinner plywood sheets and still remain building code compliant. Ideally, you want to check with your local municipality should you have any concerns when it comes to doing your roof.
The average cost of a plywood clip starts at about $15.00 USD. Among the highest quality, the H-shaped clips are known to go for $75.00 USD each. When calculating how much these would cost, can really help reduce the overall cost of a new roof installation. When stuck on a limited budget, this will actually make quite a difference in the long run. Professional roofers who do this know how important using a plywood clip is and will use these as standard practice. Should you choose to work with a professional roofer instead of embarking on this project as a do-it-yourself venture, test their knowledge about plywood clips. Good ones will know all about them and will insist on using them.
Topping It Off
When it comes to roofing projects, it’s easy to become confused about jurisdiction requirements and where plywood clips fit in as not every municipality is in agreement about them and their level of importance. There is, however, a mutual agreement among professional roofers who know and respect their craft that using plywood clips is essential to get the job done right. The stiffness it provides adds integrity to the structure, as well as the ability to cut down on all the materials needed to complete the roof, should be a convincing enough argument to go ahead and use them.
As building code regulations continue to clamp down on improving how buildings are made, the installation of plywood clips is your safe bet to ensure you are building the best possible roof your money can buy. You really don’t want to do a redo sooner than later if you can get away with it. Not only would the use of plywood clips make the roofing project cheaper the first time around but also extends the durability and lifespan. When done right, the new roof done should last as long as your lifetime.