How Thick Should Asphalt Driveway Sub-Base Be? 3 inches 16% 4 inches 33% 6 inches 33% 8+ inches 16% Get Free Quotes Today! Question: How Thick Should Asphalt Driveway Sub-Base Be? Top Answer (33% of 6 votes): 4 inches. Answer: 4 inches Explanation: 4or6 WK Construction and paving Get Free Quotes Today! Find Local Pros Free Asphalt Driveway Installation Cost Estimates Related Questions Should Topsoil Be Removed Before Building an Asphalt Driveway?Top answer: Yes What is the average width of a driveway that fits one car?Top answer: 10-12 feet wide How Long Does It Take for an Asphalt Driveway to Fully Cure?Top answer: One week Can I Put an Asphalt Over My Old Concrete Driveway?Top answer: In most cases How Thick Should an Asphalt Driveway Overlay Be?Top answer: 2 inches