Swimming Pool Tile Can Indicate Pool Movement

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A carpenter’s level can be like a swimming pool.

In order to build a carpenter’s level, a small clear tube is filled with colored liquid and an air bubble is left in the tube.  Two visible lines, or marks, are placed on the small tube.  The tube is then incorporated into a larger block of wood or metal.  When this block is level, or very close to level, the air bubble will stay between the two lines.  When the block is moved off of level, the air bubble will move past one of the lines. When the bubble moves past one of the lines, the device isn’t level.  The device works on the principle of gravity.

This same principle can be used in inspecting a swimming pool.  Pool builders presumably use a leveling device to ensure that the pool tile at the top of the water is all placed at the same elevation.  If this is done, then the same amount of tile will show above the water all around the pool.  If after a period of time some of the tile at the water level starts to show more or less tile, then this can be an indication that the soil, and the pool, may be either settling or moving upwards.  Such soil movement can be an indication the further investigation is warranted into the soils or the building pad on the lot.

Unusual Construction Problems Can Exist

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I’ve done construction law for many years, and I’ve seen a lot of construction defects.  Roofs that leak.  Walls that crack.  Inadequate foundations.  Improper framing.  Corroded piping.  Missing sheet metal. But some construction defects are more memorable than others.

Several years ago I inspected a house with a number of construction defects.  The owners had recently bought the home, and after moving in they found a number of construction defects they hadn’t noticed before.  But the most unusual one involved the backyard irrigation sprinklers.

I went outside to the backyard and saw irrigation pop-up sprinklers placed in the lawn.  When these types of irrigation systems are turned on, the water pressure forces the sprinkler heads up out of the ground and water is sprinkled for a distance of eight or ten feet.  I stood in the back yard and watched as the sprinklers were turned on, and the most amazing thing happened.  Steaming hot water came out of the sprinkler heads.  The water was hot enough that it would scald you if you touched it for any length of time.  The water temperature must have been 180º or more.  The steam rising up from the several sprinkler heads was clearly visible.

How could such a thing happen?  Why would anybody want steaming hot water to come out of their sprinkler heads?  I suppose this could be a creative—though expensive—way to melt snow off your yard—except that snow is not a problem in the Bay Area.

The property sellers had apparently done a lot of their own work on the property before listing it for sale.  Lacking the necessary plumbing expertise, they had apparently crossed the hot and cold water pipes with the result that they hooked up their backyard sprinklers to their hot water heater.  I doubt their lawn appreciated the extra warmth—and I’m sure their pocketbook didn’t.

Water Level an Old but Effective Device

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            Some years ago I had the opportunity of traveling to Israel.  My daughter was participating in a study abroad program in Jerusalem.  Israel seemed like a different world in many respects.  The culture, the food, the history, the atmosphere – everything was unique, different, and fascinating.

As a real estate attorney, I took particular notice of the construction that we saw.  Both modern and ancient construction practices, methods and materials appeared to be different from United States practices in many respects too numerous to describe here. The ancient ability to construct large and complex structures with limited technology, engineering and equipment was remarkable. But one particular engineering feat especially caught my attention.

In approximately 700 A.D., the King of Israel recognized that the city of Jerusalem was vulnerable to attack by the Assyrians, who were a large, influential and powerful neighboring kingdom.  One of the major water sources for Jerusalem was located outside the walls of the city.  The King of Israel discovered that the elevation of a portion of the city of Jerusalem was lower than the spring.  So the King developed an elaborate engineering scheme to bore through nearly 1800 feet of solid limestone rock in order to allow spring water to flow into the city.  If the Assyrians laid siege to Jerusalem, then at least the City would have water while it was fighting off the attack.

The ancient engineers and workmen dug from both ends of the tunnel – one from the spring, and one from inside the city.  After many months, the workmen met in the middle, over a hundred feet underground.   Their work is still visible today, and as a tourist, you can pay a small admission fee and walk through the tunnel, end to end, with the spring waters still flowing past your feet from the spring into the city of Jerusalem.

Here was the engineering feat that caught my attention.  As you walk through the tunnel, the slope of the tunnel floor is for the most part gradual, almost imperceptible.  The elevation drop between the start and the end of the tunnel is only a very few feet.  So without the benefit of modern laser or leveling equipment, how did the workmen properly slope the floor of the tunnel so that it was neither too steep nor too shallow?  At the point where the workmen met, the tunnel floor is smooth and nearly flawless.  How did the workmen work towards the same point, so that when they met they were both at the same elevation?

The workmen carved an inscription on the wall to celebrate their accomplishment.  But they don’t appear to have left any kind of detailed description of their engineering or construction methods.

One potential answer to these two questions is the use of a water level.  I’ve been told by civil engineers that the water level is one of the oldest leveling devices known to man, and these same engineers have also told me that water levels were used in building the Egyptian pyramids.

The concept is both simple and elegant.   An empty bowl is placed on a stand, and a twenty or thirty foot hose or tube is connected to the bowl.  A stick is fastened to the far end of the hose, and the hose runs several feet up the stick.  The bowl and the hose are then filled with water.  The water will fill the hose to the same level as the water in the bowl due to gravity.  As a result, by placing one end of the stick on a spot on the floor, the builders can tell whether that spot is higher, even with, or lower than the bowl, even if that spot is 10, 20 or 30 or more feet from the bowl.  By placing marks on the stick, the builders can tell the exact difference in elevation between the bowl and the surrounding areas.

What does this have to do with California?  Homes in the San Francisco Bay Area are often built on expansive soils that move up or down.  When soils move after the completion of a home, then foundations often move as well, and when foundations move, then floors will often move.  By using a water level, engineers can often track the amount of up or down movement in the floor of a modern California home.