Stone or brick homes that are more than seventy years old usually have weakened mortar that can affect the appearance of the home. You’ll begin to notice that the mortar is crumbly, filled with cracks, or flaking. Re-pointing is the process of professionally restoring the integrity of your brick or stonework by replacing the aging mortar.
What is Re-Pointing?
Re-pointing involves removing the old, failing mortar (up to an inch deep between the joints) and replacing it with new mortar that is compatible with existing masonry. The re-pointing process should be performed by professional masons – when done incorrectly, in can decrease property value and lead to serious damage to the structure. Note that re-pointing can be performed on structures made from materials including stones, brick, cast stone, concrete block, and terra cotta.
Why Do I Need Re-Pointing?
If you have an older home with masonry whose mortar is beginning to crumble or crack, then you should consider re-pointing. It not only improves the aesthetics of the home but increases its structural integrity and enables it to better resist moisture intrusion.
Re-pointing also increases the value of the property, provides better protection against wind-driven rain, significantly enhances its appearance, and increases the structural stability of the masonry itself. Re-pointing helps to better insulate your home against heat loss, which can lower your utility costs, and it prevents water from freezing around the bricks, which results in frost damage and cracked masonry. In short, re-pointing is an excellent means of preservation for homes and buildings, including those considered historic.
What Are the Steps in Re-Pointing?
Professional repointing involves multiple steps, including mortar matching, preparation of test panels, joint preparation, joint filling, and testing. This is all done to ensure the final appearance and functionality of the replaced mortar.
Mortar Matching
Before the work begins, a professional mason will take samples of the existing mortar. Homes or buildings that were built before the 1900s will likely have a mortar made from natural cement or lime. This means that Portland cement mortar should not be used because it will react with the old mortar and fall out of the joints.
If the building in question was constructed prior to the 1940s, there is a good chance that the bricks were manufactured from soft clay and fired at a lower temperature than modern bricks. Use of the wrong mortar can seriously damage these bricks.
A key element of professional re-pointing is mortar matching, where the new mortar is mixed to achieve a color, texture, and appearance consistent with the original mortar. Unlike the original mortar, however, the new mortar will have better vapor permeability. It will also have less compression strength than the masonry surrounding it so that the mortar will crack before the historical brick or stonework does.
Test Panels
Test panels are 3’ x 3’ areas used to establish a benchmark, or acceptable standard of work. They are prepared using the exact same technique that the mason will be using on the project. Several panels may be needed to cover different types of masonry that is involved in the project.
Joint Preparation
Joint preparation focuses on removing the old mortar. As a general rule of thumb, the mortar is removed 2 ½ x the width of the joint. This is done to ensure that a high-strength, robust bond is achieved and prevents mortar popout. Traditionally, old mortar has been removed using chisels and mash hammers because this prevents damage to the existing masonry. Many masons have replaced this manual method with the use of power tools. If used incorrectly by unskilled labor, power tools can cause serious damage.
After the joints are cleaned of mortar, they are also rinsed with a water jet to remove any remaining particles and dust. Note that joint filling should not begin if there are still standing puddles of water on the masonry.
Joint Filling
The deeper areas are filled with the new mortar. Filling the joints involves the application of several layers of compacted mortar. If the edges of the stone or brick are worn away, then the mortar is slightly recessed away from the face of the masonry. Excess mortar is usually removed using a nylon or natural bristle brush.
Testing
There are national standards for testing the re-pointing of historic masonry, including ASMT E2260-03. A re-pointing project is not complete until it has been tested according to appropriate guidelines and passed those tests.
When to Consider Re-Pointing
The bricks and stones that make up your home are made to last for many, many years – but the mortar simply doesn’t last as long. If the mortar of your home or business is beginning to crack or crumble, then it is time to consider professional re-pointing to restore its beauty and strength. Quality re-pointing can be expected to last at least 30 years, and sometimes up to 100 years. It is an excellent investment in the value of your property.
Contact McNamara Construction Today!
At McNamara Construction, we are dedicated to restoring your home and outbuildings to their historic appearance while strengthening them to last for many years to come. We work on private homes, museums, and commercial buildings. Contact us today to see what our skilled crew can do for you!
