They are generally economical up to 10 feet in height for cast concrete structures.
													
																	Poured concrete retaining wall height. 
									
	
		
	
																	Poured concrete foundation walls that are less than 8 feet tall and have soil outside that is 6 or 7 feet deep against the wall can often be 8 inches thick and function quite well. 
																	Recommendations there are some basic rules of thumb for foundation wall thickness and these are outlined in many modern building codes. 
																	Backfilling with a clay soil instead of sand can increase the load by double or more while going from an 8 foot to a 10 foot wall just a 25 height increase adds 50 to the lateral pressure. 
																	Taller walls backfilled with heavier soil risk failure unless correct design methods are followed. 
															
													
									
	
		
	
																	For example if you are pouring a retaining wall that will be 12 inches thick and will use wooden planks that are 1 1 2 inches thick for your forms you ll need to space the stakes about 15 inches apart 12 inches for the retaining wall plus two pieces of 1 1 2 inch thick wooden board.