Information about Chimney Repointing.
The stable structures of your home, including your chimney, may be strong, but this does not mean that its sturdiness will last a lifetime without needing any repairs.
For this reason, you should check your chimney once in a while to see if it requires maintenance.
If it needs to undergo any repair, then you might want to consider chimney repointing.
Repointing refers to the procedure of renewing the mortar joints’ external area.
Most people know it as pointing up or pointing.
However, the latter terms properly refer only to a new construction’s finishing process.
Typically, homeowners place their chimney at the highest part of the roof of their house. Therefore, the chimney is among the most exposed areas of the house that has to beat the blows of the changing weather conditions.
The mortar between bricks crumbling is possible as time goes. Different weather conditions and decay create some hollow cavities in the masonry units’ joints. Weather conditions may also allow some water to enter these cavities, thus causing severe damage by creating deposition, salt dissolution, and frost weathering. These can consequently result in crumbling.
For this reason, it is vital that chimney repointing be done from time to time.
How Does the Repointing Process Take Place?
Just like in any other process, observation and examination is usually the first step that the masons have to do to assess the next step that they have to implement. It includes the inspection of the chimney mortar, masonry units, and the construction techniques formerly used.
The masons should identify if the chimney really needs the repointing. Usually, if a crack is just 2mm small, it is better to leave it as it is. Damage this small will not cause a huge problem.
Chimney mortar repair may not be necessary if there is only a small crack in your chimney. In fact, cracking is common especially with old repairs because of the hard mortar shrinkage and seasonal flexing.
Aside from that, the masons will try to determine the cause of the cracks or the damage. They can see the problem indicated by the issues found in stones or bricks. This problem is one that should be addressed immediately.
Examination is also crucial to determine whether the masons should hire additional professionals like a conservator or architectural history expert. This is crucial especially if they are dealing with an old structure.
The examination is also necessary as a part of the chimney repointing process because it is how the masons determine whether the original mortar is strong or permeable enough to bout the new one.
This process is a necessary preparation for the next step. It helps the masons to identify the components of the original mortar so they can find a new one that can match it.
After examining the structure, it is important for the masons to find a mortar that can match the original one. Finding the right fit is crucial in making certain that the durability between the new and the old one are similar. The similarity ensures that the compressive strength, thermal expansion, and permeability of the chimney will be desirable.
However, the new mortar should have lower compression strength and higher vapor permeability than the original one. The new mortar’s compression strength should be weaker than the units.
Furthermore, the mortar should relieve the stress of the structure more than the masonry units. If it happens the other way around, heavy, severe, and more expensive damage can happen. For example, a repointing mortar should contain a larger lime amount if the original lime mortar is soft.
When the mortar breaks down, the expert can determine the sand and type of mortar used.
The construction part of the chimney repointing consists of two main processes. These include the old mortar removal and the new mortar filling.
The masons remove the mortar by being careful not to damage the masonry units. Sometimes, they use their hands in removing the old mortar especially if the original materials used are delicate. However, the masons remove the mortars made from hard materials with a masonry blade or grinder. They still have to be careful not to damage the masonry units.
The masons use power chisels or their hands to work with the thin or vertical joints. For the horizontal and middle joints, sometimes a power saw is used. Other tools used for removing the old mortar are a chisel, hammer, and caulking cutters.
The masons brush or vacuum the joint after they remove the old mortar.
After the removal, the masons will start placing the new matching mortar. This is done by layering, compacting, and tooling the new mortar between the bricks. This ensures that the original mortar adheres to the new one.
Lastly, the masons will apply a waterproof sealant. The sealant will prolong the life of the mortar joints.
For chimney repointing, it is helpful to hire experienced masons. These professionals know how they can match the color of the old and the new mortar. Although it is only for aesthetic purposes, it also prevents your chimney from looking sloppy. More importantly, the experienced ones can find the best materials to match your structure.
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