锘? When it comes to structural building projects nike flyknit lunar 2 schwarz , I don\t have many pet peeves. Most conventional wood-frame structures feature tried and true building practices that will stand up well to most environmental stresses short of severe quakes and tsunamis. Good materials well braced and supported are generally sufficient, even when used by less experienced builders. If there is an area of neglect, it is that many builders, professional and amateur alike, often forget that a substrate – the ground – is also a building material. So this is my pet peeve in a nutshell: why go to the trouble of installing rigid, durable materials like concrete and wood when these rest on a material that if neglected or untreated are incapable of supporting their own weight, let alone a building above them. It\s equivalent to piling bricks on a sponge. Compacting the Soil The solution to this problem is easily remedied in a word: compaction. That first of structural materials – the substrate – common to every building project from skyscraper to woodshed can be turned to a sound building material by compressing (also called \tamping\ it until it is so tightly packed that it will properly support almost any building load. In typical highrise construction, piles are used. You may have heard these being pounded into the earth, often from a great distance away. These piles are aiming for bedrock, the outer surface of the earth\s mantle. Due to settling and other compressive forces, bedrock is an ideal substrate for building. Most buildings nike flyknit lunar 3 schweiz , however, do not rest on bedrock. Although this would be ideal, it is far too expensive to drive piles deep into the earth, and in the case of most buildings, unnecessary. This is because properly compacted substrates will easily bear the building loads above them. Some substrates require no compaction at all. Some clays, for example, have been so tightly compressed over time that if dry, are said to have greater compression strength that concrete. The same can be said about some stone. We\ve often built directly on both of these materials, pinning building footings to the substrate by embedding steel pins that tie substrate to concrete footing. In some cases a clay substrate can be so dense that a sledgehammer will do no more than lightly dent its surface when struck. A similar test for compressive strength can be used for stone substrates. A hammer striking most sandstone and some granites will turn these materials to dust, but as for supporting buildings, few stone substrates will be exposed to the pound-per-inch striking force of a steel hammer. Most buildings sites don\t offer such substrates as these. Instead nike free tr 5 flyknit günstig , what a little digging reveals is a composite of sand and gravel ranging from fines to boulders, these just beneath a layer of organic material usually called topsoil. As topsoil usually contains a high percentage of compostable materials, it does not usually make a good building base and should be excavated until a so called \undisturbed\ base is reached. This brings me directly to my pet peeve. In 20 plus years of building, I have watched as numerous builders simply scrape of the topsoil, then place their footing forms directly on an undisturbed base. I long ago gave up saying anything about it; the glassy stares alone demonstrate the futility of mentioning that they are simply, and returning to the analogy, placing a brick on a sponge. Let\s stop here for a moment to consider what will happen to a building so placed. Will it fall over? Not likely. As mentioned, conventional building practice is far too sound to allow this. Instead, what will happen is that the concrete footings will settle, usually irregularly, meaning the overall building may drop inches in one area and a fraction of that elsewhere. Builders (and even some inspectors) often over optimistically assume that at least the building will settle consistently nike free 4.0 flyknit schweiz , but the result will be those cracks or fissures visible in all improperly foundated concrete work from house foundations to sidewalks and driveways. Further, the building may have a disjointed, uneven look under extreme circumstances. This is not a doomsday scenario, of course, but again, why go to the trouble of using durable materials when these are so quickly and unnecessarily compromised? How to Tamp So now that we appreciate the importance of tamping, how is it done? The easiest method is a power compactor. These come in various sizes and models, and usually rely on vibrating substrate materials until they can settle no further. Weight is a factor here also, and compacters tend to be heavy. The beauty of this method is that it exposes the substrate to far more pounds-per-inch force that the building ever will. In the event a trench foundation is being used, a compactor often called a \jumping jack\ can be dropped into a trench or pad hole and let to work its magic. Compactors will usually cause your hands to itch, and may even cause blistering nike free 3.0 flyknit günstig , so use padded gloves when using them. When tamping a small area, I\ll attach handles to a six by six beam of wood and pound the earth with this low-tech device. It, too, subjects a substrate to powerful pounds-per-inches forces, but also subjects the body to a good deal of perhaps unwanted exercise. How much compaction is required? I will usually use a length of 2\ x 4\ (5 cm x 10 cm) (or even a hammer depending on the substrate composite), pounding this against the substrate to test it. Like striking dense clay or stone with a hammer, there should not be much \give\ in a properly tamped base. There are other ways to test for degree of compaction, but this simple method works well for most purposes. Another important note on compaction is something a great many experienced builders do not know. Regardless of the type of compaction devise used, no compacters adequately compress more than a few inches of substrate at a time. This means that if you are adding fill to create a.
Регистрация 
it until it is so tightly packed that it will properly support almost any building load. In typical highrise construction, piles are used. You may have heard these being pounded into the earth, often from a great distance away. These piles are aiming for bedrock, the outer surface of the earth\s mantle. Due to settling and other compressive forces, bedrock is an ideal substrate for building. Most buildings 