Cables Shouldn’t Be Too Tight or Too Loose
International residential codes specify that a four-inch diameter sphere shouldn’t be able to pass between vertical or horizontal cables. This is for child safety reasons, to prevent small heads and shoulders from being able to squeeze through the space. Loose cables let children stretch them and widen the space between cables to crawl or stick their head through. Even if no children are in the home, maintaining enough tension to prevent cables from moving or stretching is still a requirement to pass a building inspection. From his work in construction my friend knew this, which is why his first impulse was to massively over-tighten.
How Tight Should Cable Railings Be? Consider Frame Strength
Wood and steel are popular materials for cable railing frames, and they require slightly different tensions. While, as we mentioned earlier, wood has some flexibility to return to its original shape and position if you bend it through over tightening, wood’s strength is also a universal—and pretty measly—335 pounds per square inch. This a force load that you can easily exceed with a tensioner and a wrench, which means that wood can be broken as easily as it is bent. Metals are stronger, with steel tubing able to carry around a 1,000 pounds along a 6- or 8-foot section before yielding. As my friend’s example demonstrates, though, you can exceed this by just being overenthusiastic.