For sandy gravel soils, what is the maximum foundation pressure allowed?

• A. 1000 PSF
• B. 3000 PSF
• C. 2000 PSF
• D. 4000 PSF

Answer: (B)

Allowable bearing pressure is the maximum load per area a soil can safely carry without excessive settlement or failure. Sandy gravel soils are coarse-grained and drain well, so they can support relatively high foundation loads when properly compacted and with good drainage. Under standard design practice with typical safety factors, the allowable foundation pressure for these soils is about 3000 psf. This means the foundation should not transmit more than roughly 3 ksf to the soil to avoid risky settlement or bearing failure. Values much lower would underutilize the soil’s capacity, while values around 4000 psf could be unsafe on many sites unless site-specific bearing tests confirm it. If higher loads are required, consider alternatives like deeper foundations or soil improvement.