How long must you wait before setting the second course on the base?

• A. 1 hour
• B. no waiting
• C. 2 hours
• D. 1 day

Answer: (A)

When laying a second course, you want the first course to gain enough initial stability to stay in place, but still be able to bond with the new mortar. Waiting about an hour gives the mortar time to set enough to prevent movement, while still remaining workable so the next layer can form a solid bond. If you don’t wait, the first course can shift under the weight of the second. If you wait too long, the first mortar may skin over or harden too much, reducing bond strength and creating a weak joint. So about one hour is the right balance to ensure proper alignment and bonding.