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How to Build a HouseA Practical, Common-Sense Guide to Residential Construction
By George Michael Rentz
iUniverse, Inc.Copyright © 2011 George Michael Rentz
All right reserved.
Chapter OneSite and House Planning and Design
The patch of planet Earth the house will sit on is the house site. The site includes the geographic location—where on the planet you are—and the specific physical characteristics of the earth under and surrounding the house.
The geographic location of the site includes the following considerations:
All of these items must be addressed in the design of the house.
Specific characteristics of the site include the following considerations:
These site characteristics impact the construction cost and time, and the future maintenance of the house.
Choosing the Best Site for Your House
Choosing the best site for your house can be done in two ways. First, do you already know what type of house you want (Spanish, farm, townhouse, etc.) and just need a site to build on? Will any site do as long as you can make it fit the house? Second, do you know what area you want to live in (ocean, mountains, city, subdivision, country), and will you design the house to fit the site (kind of like site-specific art)? I recommend that you choose the area you want to live in and match the house to the site. You still have certain types of houses you like but aren't dead-set on a specific one and nothing else. You're flexible—and they say that's always good, unless you're trying to row a rowboat with a rope. Unless the site you pick is so unrelated to the type of house you like, matching the house to the site is the best way to go. Keep in mind, however, that a New York City townhouse on the top of a peak in the Rocky Mountains just doesn't seem right.
Access to the site is the only thing some people think about when it comes to site considerations. What are the directions to the house? Directions to some houses in the sticks will usually include something like "Turn off the paved road just past the dumpster," but there's more to site access than directions. First, be sure there is a road to the site that can handle construction traffic, such as concrete trucks and building supply trucks. If you have to build a road (not a driveway) to get to your site, you will need to find another source for information. Road construction is a topic separate from residential construction and is not discussed in this book, except to say that relative to the cost of houses, roads are very expensive to build and maintain. If you have to build a road, don't let some levelheaded bulldozer operator talk you into letting him cut your road in for you so he can save you some money. If the chewing tobacco drips from both sides of his mouth at the same time, you know he's levelheaded. In that case, just tell him that when you want to chew some horse dung, you'll let him know. Go hire a civil engineer to design the road and supervise the construction.
Some roads are not designed for highway loads (such as tractor-trailers) and can be seriously damaged by construction traffic. Some roads are too steep for construction traffic, and the construction material will have to be offloaded at the base of a hill and double handled with four-wheel drive forklifts to get to the top. Some sites don't have roads at all. Island sites without bridges will have to use boats and barges to get the construction material to the house site. Sites without proper access for construction material will increase the cost of the construction and the time it takes to build.
The above mentioned questions involving the forces of nature (wind, rain, snow, etc.) for a general area are easily answered by the local building officials and codes and the design professionals (architect, engineers, and contractors). The physical characteristics of the specific site require a little more understanding. This brings me to one of the most important topics a person needs to understand about residential construction: water. You may think I'm getting off the site topic, but bear with me. Water is such an important topic that some aspect of it needs to be addressed now.
I know water sounds kind of simple, and it is, but it's also very important. Ninety percent of all the problems I've seen in houses have involved water. These problems could have been avoided with a little understanding and planning. If you don't think water can cause problems, just try to breathe it.
On earth, water runs downhill and follows the path of least resistance. I think the part about water running downhill was the basis for several doctoral programs at a major university; I could be wrong though. Water flowing at ten miles per hour is approximately equal to the force of wind blowing at a hundred miles per hour. Water is the universal solvent; given enough time, it will dissolve anything. Running water usually purifies itself. Fresh water weights 62.2 pounds per cubic foot, and saltwater weights 64.4 pounds per cubic foot. Water is the only liquid that expands when it freezes. Water is made of hydrogen and oxygen, both highly flammable, yet water does not burn. Cool water on a hot day is one of life's sweet pleasures. Life as we know it on earth, or anywhere else, cannot be sustained very long without water. These are just some of the properties of H2O that we will expand on later.
Water is one of the most important things to plan for when designing a house. To keep it simple, water is good and bad. To give you an example of the good use of water, consider the location of water outlets in the house. There are sinks, tubs, showers, dishwashers, water heaters, icemakers, refrigerators, drinking fountains, washing machines, steam machines, humidifiers, exterior wall faucets, pools, exterior fountains, hot tubs, irrigation, condensation lines, toilets, and the list goes on. People normally associate these water outlets with good feelings, and they should.
Water becomes bad (in fact downright mean) when it is not planned for or is allowed to go uncontrolled in and around a house—for example, water leaks. Leaks occur in pipes, roofs, basements, windows, doors, pools, etc. Just about any place where there is water, it can leak if not controlled. Have you ever tried to find a leak in a roof? Keep in mind that water flows downhill, so where you see the leak coming through the ceiling is usually not where its source is. It's somewhere uphill. Storm water surface runoff and underground water can cause major problems for a house if not controlled. If a house is on a body of water, storm surges and flooding can destroy a house very quickly. Water in the form of snow or ice can collapse a roof. Pipes can freeze and burst. Termites cannot live without water, and mold and fungus cannot grow. Wherever there is an introduction point for water, there must be a discharge point. If there is no discharge point and if the water does not evaporate, it may become stagnant and breed mosquitoes. Water can be really nasty if we allow it to be.
Preventing water from becoming a problem during the life of the house is one of the most important parts of the house and site plan. The areas involving water need careful thought. When proportioning the money to be spent on the various items in the house, do not skimp on the ones involving water. Some typical areas where water can become a problem are roof flashing, gutters, toilets, sinks, water heaters, and anything water is piped to or rain can get to.
I have witnessed many times when people think they're saving money by stopping the tile around the shower just above the showerhead and installing wallpaper or paint from the top of the tile to the ceiling. Any savings in the initial cost of the tile is quickly lost when the wallpaper or paint peels off the wall and mildew grows due to the moisture from the shower. This becomes a maintenance problem and will continue to get worse until the tile is run up to the ceiling.
A second major problem area for water is roofs. One of the dumbest things ever conceived by the construction industry is the concept of flat roofs. These roofs leak and never stop. If not designed stiff enough, they also do a thing called ponding. Flat roofs are supposed to have scuppers four inches or so above the low point in the roof. Most of them do, but the designer forgot to tell the leaves not to clog up the scuppers. Ponding is a situation in a flat roof where the water cannot run off. As the depth of water on the roof increases, the water's weight makes the members sag. When they sag, they make a little pond. The little pond can hold more water, so there's more sag, then more water, then more sag, and so on until everyone involved with the roof gives you their best surprised look—that is, if nobody got hurt.
The third problem area is storm drainage. I have seen houses that have downspouts that empty the storm water directly by the exterior wall of the house and make no previsions for it to drain off. Over time, the soil around the downspout becomes saturated from the water and loses its bearing capacity. Basically the soil turns to mud, and the foundations sink in this area, cracking everything above them.
These are just three of the things this book will help you avoid; we will cover others later on. Where all of the water comes from and goes to in a house must be thought out. If not, you may hear those dripping sounds in the night that remind you of what you read in this book.
We'll get back to water inside the house later in the book. For now, with regard to the site, let's look at how all the water that will come into contact with the site should be addressed.
When it rains, where will the storm water run? Will water from adjacent sites or the street run to your site? When you place your house on the site will you dam the natural runoff of the water? The ideal site for surface runoff or flooding would be one where the house location is, also the highest point in the site. This location would prevent water from running toward the house, and the water from the roof would run away from the house. If the house location is not at the highest elevation on the site, then some water will flow toward the house and must be diverted around the house. This is done with grading the surface with swells (swells are wide, flat ditches) and installing drains around the perimeter of the house.
If your site is on a body of water, you will have to know the high water mark. Some people call this the high high water mark because when the moon is in a certain location, the water is higher on site than normal high water. If your site has tide ranges, you need to know high tide and low tide and storm surge elevations. If you are on a river, you will need to know the hundred-year flood stages. On your specific site, there is an elevation to which the water is not supposed to rise; that's the high water mark. The living space in the house has to be above this elevation, and the remaining structure must be designed for the moving water if it can come in contact with the house.
These high water marks are measured from the elevation of the oceans. If the elevation for your house on your site is 360 feet MSL (mean sea level), this means that the house must be 360 feet above the mean sea level of the ocean. Your site may be 350 feet MSL, in which case your house would be ten feet higher than your site. These numbers vary from site to site and really only come into play if you are on a body of water or in a floodplain. If you are on a body of water, your house must be designed for the worst-case scenario of the water from a hundred-year storm. Designing a house to withstand flowing water is extremely expensive; keep that in mind if your site is on a body of water. If your site is on a body of water, it is usually on the downhill side of the surrounding sites. When a rainstorm comes, a lot of water will run through your site to the body of water.
Most sites are not involved with a body of water. However, a hundred-year rainstorm (or snowstorm when it melts) can produce a lot of water. For example, say the hundred-year storm in your area was seven inches of rain in twenty-four hours. A 10,000 square foot lot, (100 feet times 100 feet), or approximately a one-quarter acre lot, would produce 43,633 gallons of water if all the rain ran off the site. One inch of rain would produce 6,233 gallons of water over the site. If the house on the site is 2,500 square feet, the amount of water that would fall on the house in the hundred-year storm would be 10,908 gallons in twenty-four hours. Again, one inch would be 1,558 gallons. Unless the roof leaks, all of this water is going to run off the house. All of the water on the nonporous areas like patios, driveways, and streets is going to run off somewhere. If your site has the type of soil, such as sand or a granular type soil, that will allow water to soak into the ground, that's good as long as it doesn't soak into the ground around the perimeter of the house.
Some soils are very porous, and others are not. The perk test tells how fast water soaks into the ground (so many gallons per hour). Perk tests are required for septic tank permits. How fast the water soaks into the ground (perks) will determine how long the drain lines have to be for the septic tank or if you can have a septic system at all. The best way to see where and what the storm water will do on your site is to visit it during a heavy rain and watch your site and the surrounding ones. If the water does not soak into the ground quickly enough, manholes and piping may be required to drain the site. One way to determine how quickly the water needs to soak into the ground is to decide how long you want to look at a puddle of water in your yard. During a frog-drowning storm, say five inches of rain an hour, I would be happy if the water was gone by the next morning. The last thing you want is for the surrounding sites or streets to drain through your site. If there is a storm water easement running through your site, be wary. Even if the easement is piped underground with manholes, pipes clog up sooner or later, and there are always maintenance problems. If the pipes clog, what will the water do on your site?
The water table is the depth from ground surface down to where water is found in the soil. If you need a well on your site, you will have to know this. How deep the water table is determines how much the well will cost. Water tables vary greatly, from ground surface at the ocean and in swampy areas to several hundred feet deep in the mountains and in deserts. A high water table will impact the foundation or basement of the house and the driveway and roads. This is because when soil gets wet, it loses some of its bearing capacity, so the foundation will have to get bigger. Water tables on sites near bodies of water are usually at the surface elevation of the water and vary with the seasons and elevation of the water. I do not recommend putting a basement in a house if the basement will be below the water table. Even if the basement is "waterproofed" and there is a sump pump in the basement floor, the basement will leak and the sump pump will wear out.
Excerpted from How to Build a House by George Michael Rentz Copyright © 2011 by George Michael Rentz. Excerpted by permission of iUniverse, Inc.. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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