Two of the most common exterior restoration interventions for New York City buildings are waterproofing and repointing. Both address water infiltration — the single greatest threat to masonry buildings — but they solve different problems in different ways. Understanding when your building needs one, the other, or both is essential for effective building envelope management.
What Is Repointing?
Repointing is the process of removing deteriorated mortar from the joints between masonry units (brick, stone, or block) and replacing it with new mortar. Over time, mortar joints erode due to weather exposure, freeze-thaw cycles, and chemical deterioration. When mortar fails, water enters the wall assembly through the open joints, causing interior leaks, steel corrosion, and accelerated deterioration of surrounding masonry.
A properly executed repointing job restores the wall's first line of defense against water infiltration. The new mortar must be compatible with the original masonry — too hard a mortar (high Portland cement content) can damage softer historic brick by trapping moisture and concentrating stress at the masonry unit rather than the joint.
What Is Waterproofing?
Waterproofing refers to the application of a barrier system — either a coating, membrane, or sealant — to prevent water from penetrating the building envelope. For above-grade masonry walls, this typically means applying a clear or pigmented sealer to the exterior face of the wall. For below-grade conditions (foundations, basement walls), it involves membrane systems, drainage boards, and related components.
Waterproofing addresses a different problem than repointing: even when mortar joints are intact, masonry units themselves can absorb water. Porous brick, deteriorated brownstone, and cracked concrete all allow water migration through the wall assembly. A waterproofing treatment reduces the masonry's water absorption rate without sealing it completely — the wall must still be able to breathe and release trapped moisture as vapor.
| Repointing | Waterproofing | |
|---|---|---|
| Addresses | Failed mortar joints between masonry units | Water absorption through the masonry itself |
| Method | Remove old mortar, install new mortar | Apply sealer, coating, or membrane |
| Duration | 15–30+ years depending on exposure | 5–10 years before reapplication |
| Best for | Buildings with visible mortar erosion, open joints, or mortar cracking | Buildings with water infiltration through intact masonry |
| Cost | Higher per unit area (labor-intensive) | Lower per unit area (application-based) |
When You Need Both
In many cases, the answer is both — and the sequence matters. Repointing should always be completed before waterproofing. Applying a waterproof coating over deteriorated mortar joints traps moisture inside the wall assembly, which accelerates freeze-thaw damage and can cause far more harm than the original condition.
The correct approach: repoint all failed joints first, allow the new mortar to cure fully (typically 28 days), then apply the waterproofing treatment to the restored surface. This gives the building envelope the maximum protection — sealed joints and reduced masonry absorption working together.
How to tell what your building needs: If you can see gaps, cracks, or erosion in the mortar joints, you need repointing. If water is coming through the walls even where joints appear intact, you likely need waterproofing. If both conditions exist, you need both — repointing first, then waterproofing. A drone-assisted inspection can identify both conditions across every elevation in a single survey.
The Panorama Approach
Panorama Restoration's drone-assisted surveys identify both mortar joint deterioration and masonry absorption issues at the same time, across every elevation of the building. Our AI-powered quantity takeoff system separates repointing scope from waterproofing scope automatically — so your proposal shows exactly how many linear feet of repointing and how many square feet of waterproofing your building actually needs.
No allowances, no contingencies, no surprises. Just precise scope based on actual measured conditions.