NASCLA Accredited Commercial General ContractorMasonryHard
A masonry crew is performing tuckpointing on a historic brick wall. After removing the deteriorated mortar, what is the next critical step before applying new mortar to ensure proper bond and durability?
- AImmediately applying the new mortar to prevent drying of the brick.
- BSealing the bottom of the joint with a silicone caulk.
- CApplying a bonding agent or primer to the exposed brick surfaces.
- DThoroughly wetting the joints and adjacent brick surfaces.
Show answer & explanationAnswer & explanation
Correct answer: D. Thoroughly wetting the joints and adjacent brick surfaces.
After removing old mortar, the brick surfaces exposed in the joint are often dry and highly absorbent. Thoroughly wetting these surfaces prevents the dry brick from rapidly drawing water out of the new mortar, which would weaken the bond and reduce the mortar's strength and durability.
Why the other options are wrong
- A. Applying mortar immediately to dry brick would lead to a 'thirsty' brick sucking water from the mortar, causing a weak, crumbly joint.
- B. Sealing the joint with caulk is incorrect; the joint needs to be filled with mortar, and caulk would impede breathability and proper moisture movement.
- C. Bonding agents are generally not required or recommended for traditional masonry repointing and can sometimes hinder vapor permeability.
Tuckpointing Joint Preparation
The essential steps taken after removing old mortar and before applying new mortar during tuckpointing, focused on optimizing the brick-mortar interface for bonding and curing.
- Remove all loose debris.
- Clean joint surfaces.
- Thoroughly pre-wet joints and surrounding brick.
- Ensures proper mortar hydration and bond.
Memory trick: Clean, Wet, Pack, Tool, Cure: The repointing mantra.