Nari: Rock Solid Site Planning

A leaky basement, cracks in the foundation, a broken underground gas line, water ponding in a yard, and an unbuildable addition. What do all of these have in common? The answer is poor site planning. 

As remodelers, we often spend a lot of time insuring that the project is aesthetically pleasing, that it is buildable, and that we make a profit at the end of the job.  We might be well advised to spend a little more time, during the planning stages, studying how our proposed project is affected by the sight that it will set on. There are several areas that we should give attention to as we do site planning. They are Legal, Physical, Vegetation, and Utilities. Let’s consider these one at a time.

Legal

Every building built must reside within the legally established confines owned by the deed holder. Most municipalities have set into motion zoning laws that regulate, not only the size of the construction, but also the location and position of the construction. There may also be limits upon the percentage of lot coverage. These zoning laws will differ from area to area.

They sometimes even change with time. What may have been allowable just a few years ago may not be permissible today. In such cases a zoning variance may be required prior to obtaining a building permit. As a site is scrutinized by the remodeler setbacks and easements must be given consideration. Lot boundaries must be determined with a great deal of accuracy. If the property boundaries are in question a survey may be required to insure that the new construction is in the proper location.

Physical

There are many physical factors to take into consideration when a new area is to be built. Most of the factors center around the displacement of water on the site. For example, in some areas Flood Protection Elevations are determined based upon 100-year floods. A building placed within these floodplain areas must be 12” above this 100-year flood elevation. Most of the construction that we do disturbs that previously natural flow of water. The topography or differences in surface elevation must be determined prior to the start of design. A determination of how water from the roof and driveways will be disposed of must be made. Is it legal for the water to flow offsite or must it be retained within the property boundaries? If there is particular problem that must be dealt with a good civil engineer can be a lifesaver.

Another factor that may affect a hilly site is the amount of imported or exported soils required. It is generally recommended that soils brought into a site be compacted in 6” increments or lifts. On the other hand if a basement is part of the project, can the spoils of the excavation be wasted on site or do they need to be hauled to some other site?

Will a septic system be needed? If so a percolation test will determine the size and type of the drain field needed. At the time that a percolation test is performed it may also be a good idea to have a soils test done. This test will determine the weight bearing capacity of the soils. Some soils, such as peat moss or clays of high plasticity (they expand when wet and shrink when dry) make poor foundation materials. They may have to be excavated out and replaced with soils that will provide the desired bearing strength. One builder had to excavate an extra eight feet in depth to get rid of peat moss that was found in the area of the new basement. Imagine the cost of that! The depth and width of the footings are determined by the weight bearing ability of the soils. The depth of the footings will also be determined by the frost level. To prevent heaving the footings must extend below the frost level.

Finished grades around the building are also important to consider. The ground should slope at least 5% away from the building for the first 10’.  This will aid in preventing water from building up around the foundation and possibly finding its way into the crawlspace or basement. If the topography of the property or the type of soil onsite warrant it, a drainage system around the building may be desirable.

Vegetation

Remodeling is often done to homes that are several years old. As a result landscaping has matured significantly. While this feature is attractive, it is something that must be kept in mind when giving attention to site planning. Mature trees can present some challenges. Their root systems often extend beyond the drip line of the tree and can interfere with the foundation of the building. Care should be exercised in the placing of any new additions to the home. Most homeowners want mature trees to survive remodeling, so care will have to be taken so as not to damage the root system. As a rule of thumb, roots should not be disturbed within the drip line of the tree..

Utilities

Prior to the start of design, underground utilities should be found. This will prevent an unplanned discovery later. If utilities need to be installed on site, proper planning can alleviate significant costs and construction delays later. Placement of these utilities will need to be coordinated with their respective providers. There are limitations as to placement. For example, sewer and water may be run in the same trench if the water line is above the sewer line. However, in a rural setting where a septic system and well are needed, they should be no closer that 100’ apart.

Proceed to the test

Loading