Which joint profile is commonly regarded as the most weather resistant on exterior masonry walls?

• A. Concave joint
• B. V-joint
• C. Raked joint
• D. Flush joint

Answer: (A)

Water control in exterior masonry hinges on joints that shed water and stay tight over time. The concave joint does both very effectively. By forming a rounded, inward groove, this profile compresses the mortar and creates a curved channel that discourages water from penetrating. The rounded shape reduces the surface area where capillary action can draw moisture into the joint, so water tends to run off rather than seep in. The tight, dense mortar also resists cracking from freeze–thaw cycles, helping keep the joint watertight longer.

In contrast, a V-joint is often decorative and can channel water or crack more easily; a raked joint leaves a recessed, sharp-edged slot that can trap moisture and deteriorate quicker; a flush joint sits level with the wall surface and, without the extra sheltering contour, doesn’t shed water as effectively.