Selecting Your Site

Selecting a Site

Research the site

The first step in the process of building your custom home is selecting an appropriate building parcel. Before you get locked into any building plan you need to research your site in great details, because general site conditions, lot size, front and rear set-backs, side-yard set backs and height and view restrictions affect the size of your design and the building cost. No architect or designer can produce quality home plans for you without a detailed site plan, and no builder can estimate your home construction costs without first knowing where it’s being built and what soils are supporting it.

 Gather Information

Complete your due diligence before starting any design. It’s best to have complete site information before you build, but you can gather a lot of good data on your own before you hire a geologist, geo technician or a soils engineer. Ask the neighbors: they will probably know if there’s a ledge, a high water table or problem soils. Get information on setbacks and side-yard requirements from the local building department and the HOA. Take a good look at the site yourself to determine if the lot sits high or low compared to other homes and properties in the immediate area. If it appears to be lower, it will probably require dirt fill, which can be a costly added expense. Start with the soil analysis and make sure it is stable.

Soils analysis

Since your land may have several layers of various soil types, your builder and designer need to know exactly what they are building on. Most critical layers are from the surface down to fifteen feet or greater below your planned foundation, because foundation codes are written for sandy soils, which are the best natural soils for construction. Heavier silts and softer clays are not ideal and may not meet the minimum code requirements. Most building departments will require detailed foundation design based on the soils engineering report, which is based on site survey by a licensed soils engineer, “soil borings” and possibly test pit samples. It should contain construction recommendations for the type of foundation that is recommended or required.

Quite often, the excavator will discover water when digging the foundation hole or test pit. This is not necessarily a problem, since water levels fluctuate from season to season in response to rainfall, drought, and melts. Engineers and site planners do, however, need to identify the water table (depth where water sits year-round) and its’ high point. They do this by analyzing the color or “mottling” of the soil in the pit. Foundation footings and slabs should sit above the water table. On a site with a high water table, you may have to bring in fill to raise the grade.

Drainage is essential

Soil drainage varies depending on the type of soil. Sandy soils drain better than silts and clays. If the native soil is sand you can use the soil from your excavation to backfill the site. Since silts or clays typically don’t drain well, only some of them may be used as fill mixed with sand. However, if the excavated soil is not suitable, additional appropriate fill will have to be imported. Your lot must always be properly graded so the water will drain away from the home

Septic system

If your house needs a septic system, the water table and soil drainage are issues once again. Septic disposal or “leach” fields are serious items that should always be investigated by a licensed soils analyst. In some cases you may need to build up the lot with fill to meet the local requirement, which can be complicated and expensive, since trucking in a clean fill is very costly. The time and money you spend on site investigation is an excellent investment and essential insurance against possible problems later when properly designed foundation really counts.

 

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