Materials Dictionary

I'm in the process of updating all our projects to include the metric measurements as well. Better for me to do it once then for every metric using reader to have to do it. But in addition to that, I figured that a material guide was in order as well. I'm going to cover a few of the most used materials at Homemade Strength to help you understand them, as well as choose metric equivalents.

Please note that I live in the United States, I have never visited a hardware store abroad, so I don't specifically know what materials are common in other countries, nor exactly what they are commonly called or what they typically cost. Prices quoted on project pages are for common, major chain, hardware stores in the U.S. at the time of their writing (may be more around major cities), and don't usually include any tools you may need to buy if you don't already have them.

  • 2 x 4 STUDS
    These are the common boards used to frame a house. They are both inexpensive and strong. You don't have to get "premium" or fancy grades. Normal studs are fine. As I said, they are used to frame your house (at least in the U.S. they are) so they are plenty strong.

    2x4s are called that based on the original dimensions of their height (thickness) and width. They do start out those dimensions but by the time they are processed and in the store they are actually more like 1 1/2" x 3 1/2". In other words, the actual dimensions are 38mm x 89 mm. They come in varying lengths. I usually get the ones that are 8 feet (244 cm) long because they fit in my car so I don't need a truck to get them home.

  • 4 x 4 POSTS
    These are mostly used for decks, mailboxes, fences, and any outdoor project in which you set a post into the ground, usually in a hole with concrete. Their actual size is more like 3 1/2" x 3 1/2" or 89mm x 89mm. I don't think I have, as of yet, used them in a project.

    The same applies to basically all lumber. In the States we generally just call things by their original (before drying etc.) height and width. Remember that 1 inch is 25.4 mm. From what I gather, how boards are measured and labeled in metric using countries are all over the place. It may or may not depend on where the lumber is imported from. And of course it varies from country to country. Some use metric for everything but still measure wood in inches. Some measure height and width of boards in mm but length in "boardfoot." I will simply give you the common names of materials based on inches (2 x 4) as well as the exact measurement of the board's width and thickness in millimeters (38 x 89).

    Also used heavily in the construction of your roof and/or walls. I need to be absolutely clear here. I've gotten into the habit of slangly calling these types of boards "plywood." In fact, the material I use most commonly is not plywood at all, it's Oriented Strand Board (OSB), also called "waferboard. I rarely use "plywood" at all. I will likely go back and update the projects to make this distinction.

    Plywood (left), Oriented Strand Board (right)
    I have no idea what these materials are called in different languages, but see the picture for clarity. Plywood is composed of thin full sheets of wood glued together. As such it has a grain. From the top it will look like a big single piece of wood. The side will reveal that it has multiple layers. OSB, what I typically use, is a bunch of little scraps and pieces of wood all glued/pressed together. It doesn't have a grain, it looks like exactly what it is, a bunch of scraps flattened together.

    Particle Board (left), MDF (right)
    Particle board / chipboard is commonly used for shelving in closets. It is made by pressing a bunch of tiny wood chips/shavings together. MDF is a similar product but is denser / made of smaller fibers, and is therefore smoother.

    The truth is, for our applications (an INDOOR gym) mostly all these materials will work the same: plywood, OSB / waferboard, particle board / chipboard, or medium density fiberboard (MDF), whenever I call for "plywood." I've heard that "plywood" can be costly in some countries, so feel free to use whatever you have available / is most cost effective.


These types of fasteners have multiple identifiers to label them. I don't want you to get confused so don't freak out. I will try to make it simple. We can categorize them in endless ways but let's just distill it down to what is most practical.

    Bolts and Screws are your two main fasteners. They are not the same thing. A bolt doesn't bite into the material it is fastened to. It simply goes through the hole in said material the material is clamped between the bolt head and the nut threaded onto the other side of said material. There may or may not be metal washers involved to spread out the forces.

    A screw actually bites into the material itself. It usually will not go all the way through said material and there are no nuts and typically no washers involved in the process.

    If want you to use a bolt I'll say "bolt." If I want you to use a screw I'll say, "screw." Simple enough.

    This one is simple. Wood Screws, Decking Screws, Sheet Metal Screws, etc. If I'm using terms like this, then things are obviously not too complicated, given the general nature of the classification. I use what I call 'deck screws' for most projects to denote wood screws that are designed for outdoor decks. They are usually labeled as such or "external" on the packaging. I try to use these whenever possible to avoid you needing to get many different types of fasteners. I like to keep things simple, unless we need a particularly smaller screw for something.

    The next way to identify a fastener is by it's head, the type of head it has determines the tool you need to fasten it. Whether it has a hex head, a Phillips head, flat head, star head, etc. Be it a wrench/socket wrench, various screwdriver bit, allen wrench needed to fasten it. As I said, I mostly use deck screws, and the head type I prefer is T-25 star bit for its superior grip and torque, it's just easy to work with. But in general, the type of head you get doesn't really matter as long as you have the tool to fasten it. The only exception I can think of is that, in some cases, a carriage bolt may be specifically needed.

    Carriage bolts have a smooth head (no tool to drive it in). Under the head they have a square portion of metal followed by the smaller threaded shaft. This square is used to fit into a square hole in the material you are fastening. This is what prevents the bolt from turning as you tighten the nut. As I said, most of the time it won't matter specifically what type of fastener head you use, unless (like on some saw horses) you are specifically needing a carriage bolt to fit in a square hole.

    What the fastener is made out of. Zinc, Stainless Steel, etc. This will pretty much never matter for our purposes. Get whatever, I don't care. You probably won't have much choice in this matter anyway once you narrow it down by the head type and size you want. As such I will never mention this again because I don't care what your screws are made out of as long as it's a metal of some kind.

    This one's easy and important and I will obviously tell you what length to get. This doesn't necessarily mean it has to be exactly what I say, but if you do deviate from my instructions, just make sure you understand what you need it to do, and get something that will work.

    This is the diameter of the bolt shaft. We're not going to make it more technical than that. You don't necessarily have to get exactly what I say as long as you understand that any changes you make may need other changes (bigger or smaller holes, different nuts and washers) to be made. Of course, common sense tells you that your bolts and nuts must be the same diameter. If you use 1/4" bolts, use 1/4" nuts. If you use 10mm bolts use 10mm nuts.

    This only applies to bolts/nuts. TPI (imperial) and thread pitch (metric) essentially denotes how many threads are on your bolt. There are a few different categories typically classified in such terms as "course" or "fine" or "standard, fine, extra fine." This only matters in the sense that your bolts and nuts must be the same. I will never make reference to this in a project since it doesn't matter. If you get standard bolts, then get standard nuts. Common sense, but you have to be aware that there are options. Not all 1/4 inch nuts will fit on 1/4 inch bolts if their TPI / pitch is different. So if your nuts and bolts aren't working together even though they are the same size, your thread pitch is off.


This is the key here. You don't want to or have to measure any of this stuff. All you have to do is read the label. But you have to be able to understand the label as well. Metric differs from the American labeling slightly so we'll cover both.

    The first picture below (left) is from a package of carriage bolts. Obviously it's going to say "carriage bolts" on the package. The top line is what we're really interested in, the sizing. "1/4-20 x 3 -1/2"

    This is what that long jumble means: "diameter - TPI x length." The first number will be your diameter, in this case 1/4 inch. This will be followed by a hyphen and another number, this is the thread TPI figure. It will vary depending on the diameter of your bolt. There are two possibilities for each diameter (one coarse one fine) but instead of just simply saying it's coarse or fine they put the actual TPI figure. For a 1/4 inch bolt "20" denotes the "coarse" TPI. For other diameter bolts, other numbers (not 20) will denote that it's coarse. Again, don't get wrapped up in this too much.

    The specific number only matters so that your nuts and bolts can be matched up. So in this case, "1/4-20 carriage bolts" would need "1/4-20 nuts." And in America it will always be labeled as such "diameter - TPI" We don't care what the number is or whether it's coarse or fine. We only care that our nuts match our bolts. The last number is merely the length of the bolt. In the above case it's a 3 1/2 inch bolt.

    You can see in the other picture above, a package of nuts. "6-32 Hex Nuts" This one obviously doesn't have a length figure because they are nuts. But again we see the "diameter-TPI" format. In this case, the nuts are less than 1/4" in diameter so their size is denoted by a generic size figure instead of a real measurement. Our bolts were 1/4" so they were simply labeled as such. The nuts are "size 6". After the hyphen we see a "32" which happens to be the course notation for size 6 bolts/nuts. Again, the exact figures, in this case 32 only really matter to match up your nuts and bolts.

    I don't have pictures but the labeling will be similar to this: "M14 x 2 x 20 CL 8.8"

    First and foremost, the "CL 8.8" is the "class" or grade of material. It's the equivalent of seeing "Zinc" on our above American labels, or "Stainless Steel". In other words, we don't give a shit about it. As long as your bolt or screw is made of metal, we don't care. So ignore it. For our purposes it doesn't matter.

    The rest is labeled similar to the American labeling, except that metric uses a different scale to measure the threads. But again, we don't care about the specifics of that, as long as our nuts and bolts match.

    "M14 x 2 x 20" means "diameter x thread pitch (TPI equivalent) x length". Basically just like the American format, but instead of inches or generic sizes, the diameter is always measured in millimeters. And instead of TPI it's thread pitch, which for our purposes they are all just generic numbers anyway. As long as nuts match bolts who cares what it says. It may as well say "M14 x brown cow x 20" for all I care.

    Nuts will be the same except they won't have length dimensions for obvious reasons. If you get "M12 x 1.75 bolts" then obviously get "M12 x 1.75 nuts."

So, now if I tell you to buy 2 inch long size 8 bolts and wing nuts (or 50 millimeter long M4 bolts and wing nuts), you'll know how to pick the right ones from the labeling on the package/bulk bin.