Why mortar fails first
The Rowhouse Manual puts it plainly: “Next to neglect, water is your rowhouse’s worst enemy.” Mortar sometimes deteriorates before the brick does, and open joints let water into the wall. In freezing weather, water trapped in brick expands and breaks the surface, which is called spalling.
What a good repointing job involves
- Raking out to the right depth. NPS Preservation Brief 2 says old mortar should be removed to a depth of 2 to 2½ times the joint width, which usually means ½ to 1 inch for brick.
- Hand tools where the brick is soft. The same brief warns that power saws can damage soft historic brick. The Rowhouse Manual says thin butter joints should be raked out by hand, not sawn into a larger joint.
- Mortar matched to the brick. New mortar should be softer and more permeable than the brick, and should match the old mortar’s color, texture and joint profile. Lime vs. Portland cement.
- The right weather. NPS says repointing should be done when wall temperatures are between 40°F and 95°F.
- A test panel first. NPS recommends a trial area, about 3 feet by 3 feet, to check the mortar match before the whole wall is done.
Spot repair or the whole wall?
NPS notes that when 25 to 50 percent or more of a wall needs repointing, it’s usually better to repoint the whole wall for a uniform look. Smaller areas of failed mortar can be repaired, as long as the new joints match.
Costs
HomeGuide puts repointing at $500–$2,500 per 100 square feet nationally. A Philadelphia contractor publishes $8–$25 per square foot locally, with most rowhome jobs at $12–$18. Full cost guide.
Permits
- Usually no building permit. L&I lists “pointing masonry” among the projects that often don’t need a building permit, as long as the property is not on the Philadelphia historic register.
- Historical Commission review if the house is on the register. The City says project reviews are required for “masonry cleaning, painting, pointing, repair, replacement, alteration, or removal.” Review is free, and staff often approve applications without sending them to the full Commission.
- A Streets Department permit for scaffolding on the sidewalk. Scaffolding, shelter platforms and dumpsters in the public right-of-way need a street closure permit. Applicants must hold a Contractor License or Commercial Activity License and apply at least 10 business days ahead.
- A licensed contractor. Ask for the firm’s Philadelphia Contractor License, or its Pennsylvania Home Improvement Contractor registration if it only works on existing one- and two-family homes.