Pile foundations are used when the soil cannot support building loads. Piles transmit loads directly to stronger soil or bedrock below. Piles can be made of steel, concrete, or timber. They function to transmit foundation loads vertically and resist lateral and uplift loads. Concrete piles are commonly 10-20 meters long and support 300-3000 kilonewtons. Pile foundations can be end bearing piles that extend to bedrock, or friction piles driven through soft soil to a specified depth without reaching bedrock. Pile caps are reinforced with steel to resist tensile and shear stresses from heavy point loads.