Building a Better Gate...
In order to make a gate that stands the tests of time and use, there are some basic principles that should be followed. Using leverage to make a gate more stable, rather than easily deformed is the key.
Everyone has seen the old fashioned wooden gate with a Z-brace, a diagonal intended to make the gate more rigid. Most fence guys will tell you that there are only two ways to put in a Z-brace. The right way, and the wrong way. Some say it should go from the top hinge to the lower outside corner of the gate to “hold it up”. Others say it should go from the lower hinge, up to the upper outside corner to “lift it up”From years of experience, they will tell you that the way they do it is best. The problem is they are both right. Except when they are not. More important than which direction the brace runs is the angle it runs in. That angle will determine whether the brace supports and makes the gate more rigid, or whether it adds unnecessary and unsupported weight to the gate, making it weaker than it would be without the extra brace.
Next time you ride over a bridge, look at the supports. They are designed to form a “truss”, which is a stable form. Trusses are based on triangles, among the most stable of geometric constructs. (Think “pyramid”, very old, very stable.)
To make your gate as strong as possible, and prevent sagging, the key is keeping diagonal braces to 45 degrees or less. This allows the brace to apply a vertical force, supporting the weight of the gate against gravity, rather than a horizontal force, that results in sagging and twisting of the gate. These principles apply no matter what material you build your gates with. Proper bracing, at 45 degrees or less, is the key to success.
If you are running into problems with a gate design, or would like more detail about why the 45 degree rule is the most important factor in bracing a gate, call Modern Fence Technologies at 888 456-6786. Or, if you are on the West coast, call our Carson City, Nevada branch at 888-613-8146.
On a metal gate, the diagonal should go from the hinge side high, to the latch side low. This is called being in "tension" vs. the alternative which is called being in "compression". Assuming that the welds hold, (which is an assumption that should be made), the question is whether the brace is more likely to stretch or compress, and compress includes bending. It will always take more force to stretch a metal brace, than it will take to bend one. That is why a truss rod works in one direction and not in the other.
ReplyDeleteOn a wood gate, your braces need to be set the other direction, or in "compression". You cannot weld the ends of the wood together, and there are not great fastening systems for that. In tension the fasteners that are normally used will pull apart; in compression normal nails or screws will normally do the trick.
Thank you for adding to the discussion. Those are all excellent points, and likely to be included in later articles on gate building. People tend to avoid longer posts, so I intentionally left out the finer details in order to get to the point about truss forms in gate building. I look forward to hearing your comments on the next gate building post.
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