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Re-Pointing - « back to F.A.Q.s
Summary
Re-pointing is the removal of failed or deteriorated mortar from the joints of any masonry wall, and reinstalling new mortar that has been specifically formulated for a given unit type. When done properly, re-pointing will protect a building and envelope system while maintaining the buildings presentation. Improperly done, re-pointing not only looks poor, but may cause damage to the masonry units themselves. |
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How does one know if masonry needs to be re-pointed? |
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The mortar joints may have obvious cracks; mortar may be missing altogether or be deteriorating and spalling. If left unchecked, water will find its way into the masonry, and at this point likely has. Once water penetrates the masonry units and wall cavity, the freeze thaw cycle of our climate begins to deteriorate the masonry units. Water expands 9% with a force of three thousand PSI. Water penetration is evident in many ways.
- Efflorescence: this is the powder like substance you see on bricks. This powder is actually salt crystallization being drawn out of the brick, as the unit dries from back to front it pulls the salt though it. As the salts collects under the surface of the unit the deterioration process is rapidly accelerated.
- Masonry units will start to show signs of spider cracks. This is caused from the units becoming saturated. Imagine a sponge that in saturated with water and then freezing it. The unit is stressed and quickly fails.
- The masonry joints may become soft. As with the masonry units themselves, the joints also becomes saturated and begin to fail.
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How do I know if the proper steps are being followed, and that I’m getting a lasting restoration and value for my money? |
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Here is a short list of what you should expect from your masons.
- The existing mortar should be inspected to find a suitable match. The mortar should be of a grade to work with the units. For instance, a modern brick or block should have a type "S" mortar (the mortar should be hard as to better work with the unit) while a soft brick such as a heritage unit should use a heritage grade mortar (softer mortar, less portland cement and more lime).
- Joint preparation is critical to a lasting restoration. The depth of the joint should not be less then 25mm too prevent flashing. Flashing is when the mortar sets to quickly; this turns the joint a white color and weakens the mortar. The wall should first be moistened but not soaked. Over saturating the wall will causes the mortar to bond poorly to the masonry units.
- Adhering to proven procedures while installing new mortar.
- Make sure you have a contract in place that states under no uncertain terms what procedures are to be followed.
- Use only qualified masons and their apprentices.
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