How to Build on Fill Dirt

Cheap Fill Dirt is Fine if You Do It Right

Fill dirt is commonly added to building sites to create a level area on which to build. While it is an economical way to create a building site, unless you properly prepare the fill dirt before building you will wind up with major structural problems just a few years into the age of your building. You can build on fill dirt without future problems if you follow know the soil classification of the site, of the fill dirt, and properly prepare the fill as a construction base.

Things You'll Need

• Water
• Compactor
• Shovel
• Site Soil Information
• Density Tester

Instructions

1. Spray water over the entire area of fill dirt a minimum of 10 feet beyond what will be the exterior foundation of your building. Don't saturate the dirt to the point that puddles form, but the surface should be uniformly darkened by the water.

2. 

   Compact the soil. Work in a grid pattern so you can keep track of where you have compacted and what still needs to be done. If, while compacting, the surface of the fill dirt caves in or sinks out of level, use a shovel to add more fill dirt and compact again until the surface is fairly level.

3. 

   Test the soil density. Use a soil density tester only if you are well versed in the machinery. It is recommended that you hire an outside testing company to do the testing.

4. Compare the density test results with you site soil classification, the classification of your fill soil and requirements for soil density of your zoning codes. If you fall within an allowable range, begin to build. If you do not, if you "fail" the density test, spray water on the fill dirt, compact and then test again.

5. Begin building in a normal fashion. Once fill dirt has passed a density test it can be treated like any other building site.

Tips & Warnings

• If you are going to be digging down and pouring concrete foundations on your building site, wait until you have dug them out and then compact and test rather than do the process twice.

• Never use a soil density testing machine unless you are trained to use one, these machines utilize radioactive materials to conduct their tests and can be extremely dangerous to use.

References

• soil classification of the site

Resources

• Read the Soil Compaction Handbook