Key takeaways
- Use mortar softer than the brick.
- Never sandblast old brick.
- Repair, do not replace, whenever possible.
- Test before you touch.
The biggest mistake: hard mortar
Modern Portland cement mortar is harder and less breathable than the lime mortar that held old brick together. When hard mortar is used on soft old brick, moisture and movement have nowhere to go except through the brick, and the faces flake off. A softer mortar lets the joints take the wear, as they were designed to.
Always test the old mortar before choosing a new mix.
Cleaning and coatings
Sandblasting and strong acids strip the hard outer skin from old brick and open it to water. Gentle, low-pressure cleaning is the safer choice. Avoid film-forming coatings and paints that trap moisture, and choose breathable products when sealing is needed.
Replace damaged bricks with a match in size, color and softness.
Work with a mason who tests first
A good preservation mason cuts a test panel, matches color and tooling and documents the work. That small step saves the wall from irreversible mistakes.
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Quick answers
Can I use modern mortar on old brick?
Usually not. Modern cement mortar can be harder than old brick and cause damage. A softer mortar chosen after testing protects the brick.
Should I paint old brick?
We generally advise against it. Paint traps moisture and is hard to remove later. A breathable limewash is a better choice if you want a painted look.
Ready to talk it through? Get a free estimate or call 615-431-3789.