Pole Barns » Pole Barn Construction » Soil Ratings

Soil Rating Chart

Two considerations when planning your pole barn project are the slope of the land and soil characteristics. If you have a flat site location then site leveling will be much cheaper than one with significant slope. If your soil is poor, then post hole diameters can get rather large.

Refer to our soil bearing capacity page to get more info about your jobsite. The three main inorganic components of soil are:

♦ sand
♦ silt
♦ clay

In general, gravelly and sandy soil types are better than clay types of soil. See this page for pole buildings additional information on designs and styles.


SOIL TESTING
To determine soil characteristics, dig several test holes around the building site. Each hole should be several feet deep. Make them deep enough to show a complete soil profile since there are various levels of soil.

Typically, a soil profile will contain:
1) several inches of topsoil
2) a deeper layer of subsoil composed of sand, silt, and clay
3) a layer of substratum that is unweathered rock and gravel.

The 2) subsoil is the soil we are most interested in when planning a pole foundation.

 

RATINGS FOR SOIL TYPES
  General Characteristics Special Characteristics Usage Undisturbed Soil
  Hydrologic Reaction   Foundation  
Soil Type Stability Permeability Corrosion Compactability Pack Expand Frost Foundation Drain Frost Dense/Hard Loose/Soft Drainage
Bedrock EX NS EX VP NS NS VP EX NS VP EX EX NS
Gravel EX EX EX EX EX VP EX EX EX EX EX EX EX
Gravel/Sand VG VG EX VG EX VP EX VG EX G EX NS EX
Gravel/Silt MED G-P EX G VG P G-EX G VG G-VG VG VG VG
Gravel/Clay F VP VG G G F G-VG G VG F-MED G EX VG
Sand G EX EX EX EX VP EX VG EX VG-MED EX VG-EX EX
Sand/Silt F-G G-P EX G G F G G EX F-VP VG VG VG
Sand/Clay F VP VG G G F G MED NS F G VG VG
Clay/Silt P G-P VG F-G G F G-MED F NS P-VP G G VG
Clay P VP G G MED MED G F NS F-P G-VP G-MED VG
Organic Silt P G-P G F F G G P NS P-VP G-VP G VG
Inorganic Silt P GP VG F-G F G V-MED VP NS VP MED G VG
Inorganic Clay VP VP G F-G F G G P NS VP-F MED-P G-VG NS
Organic Clay VP VP G F F G G VP NS VP F-VP MED NS
Loam NS NS MED NS NS NS VG NS NS NS F NS NS


EX-Excellent, VG-Very Good, G-Good, MED-Medium, F-Fair, P-Poor, VP-Very Poor, NS-Not Suitable

Cited: FHA Bulletin # 373


Next » Soil Bearing Capacity
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