Chimney Masonry and Repointing

Chimney Masonry repair is the art of using mortar and concrete in the repairing of your chimney. In most cases this will including repairing the masonry joints between each brick in your chimney and repairing the chimney crown. Each repair uses a different type of material to achieve the best possible results. 

At some point in its life cycle your masonry will need to be repaired. In severe cases masonry will have to be completely replaced when it is overly neglected. This is when a complete chimney rebuild is in order.

Masonry damage occurs when the incorrect mortar or cement was used when it was built or during another repair. Damage also happens when years of harsh weather or water infiltration deteriorate the crown or joints between each brick. This erosion happens frequently in our wet climate here in Philadelphia. Chimney masonry damage also occurs in cases of severe events – such as chimney fires. In these cases your chimney waterproofing and chimney flashing need to be inspected. 

Licensed repair experts, such as those who work with Philadelphia Chimney Sweep, use essentially two type of materials to repair your chimney masonry. 

1. Cement. Cement is used exclusively on your chimney crown. Cement is a harder substance, that doesn’t breath well, but does a very good job at holding up to harsh environment and weather.

2. Mortar. Mortar is used between your bricks or stone to create joints. Mortar is a softer material that affords your chimney some small movement – hence the name joint. It’s also breathable. So when moisture needs to escape it goes through the mortar and not the brick, which then can be damaged.

Repointing Chimney Brick

There may come a time that the mortar in your chimney needs some care. This would be brought to your attention during one of our thorough safety inspections that the mortar needs some love and attention. Our highly trained inspectors will determine if repointing the chimney is a viable solution or if a chimney rebuild is necessary. 

This decision will all come down to how deep the damaged mortar goes. If water has penetrated the mortar for some time and the damage is deep or the erosion is severe, a rebuild is required. However, if the damage is superficial, a repointing should do the job. 

Repointing is when the damaged mortar joint is removed from between the brick and new mortar is put in its place. This is seriously hard and time consuming work since the existing mortar needs to be cut out from between the brick first and we only work on small sections at a time for safety. 

Think of repointing as repairing a tooth cavity – the damage is removed, cleaned, and replaced with material that is more structurally sound. 

When cleaning out the damaged mortar, we only go 1 inch or 20% into the mortar. If going deeper is required because of damage then we will consider rebuilding that area of your chimney. Any deeper than 1 inch over a large of area of your chimney will affect its structural integrity.  

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Here is a brick chimney with new masonry with new repointing completed in philadelphia. In the foreground is a blue cloudless sky.

Proper Chimney Masonry

There are two areas in repointing where chimney masons don’t do a proper job that your property deserves. Since we are aware of these pitfalls, Philadelphia Chimney Sweep knows to watch out for these things. 

1. Using the Correct Mortar. When repointing you need to match the type of mortar used in the original chimney as closely as possible. This is for proper adherence – so the mortar stays as it should. Brock protection – a harder mortar against a softer brick will damage the brick which will require replacing. This is especially true with older homes around the Philadelphia area. These much older homes use a softer type of mortar.            

2. Color match the Mortar. When you get your chimney repointed you don’t want to make it look like it was repaired – in the sense that the repointing is easily visible. New repointed should blend in seamlessly with your original mortar.