Residential Building Inspector B1Footings and FoundationsEasy
A residential building is being constructed on a site where the soil is classified as 'clayey sand' (SC) according to the Unified Soil Classification System (USCS). What is the presumptive load-bearing value for this soil type as per the 2021 IRC?
- A4,000 psf
- B1,500 psf
- C2,000 psf
- D3,000 psf
Show answer & explanationAnswer & explanation
Correct answer: C. 2,000 psf
According to IRC Table R401.4.1, the presumptive load-bearing value for sandy clay (SC) is 2,000 psf. This table provides standard values for various soil classifications.
Why the other options are wrong
- A. This value is typically associated with gravel, sandy gravel, or silty gravel (GW, GP, GM, GC).
- B. This value is typically associated with clay, silty clay, or clayey silt (CL, MH, ML, CH).
- D. This value is typically associated with sand, silty sand, clayey sand (SW, SP, SM, SC). However, for SC, 2000 psf is specified.
Presumptive Load-Bearing Value
The assumed maximum soil pressure that can be safely applied to a foundation without causing settlement, based on soil classification.
- Values are listed in IRC Table R401.4.1.
- Used when a geotechnical report is not available.
- Varies significantly by soil type.
Memory trick: Soil's Strength: Know Your Limits for a Strong Build