Brick in need of tuckpointing

When it comes time to replace old mortar from the joints of masonry, brick or stone in your Chicago older home you may have multiple concerns.  Will it maintain the appearance of the original? Will it strengthen the structure and provide better resistance to Chicago weather? Is it important to maintain the chemical properties of the original mortar? Tuckpointing mortar in Chicago older homes is a masonry restoration process.

In older homes, every brick was laid by hand and the mortar filled with a trowel. Over time, those mortar joints need repair (cut, clean and refill with fresh mortar).

Protect the History of Your Home

If the house was built between 1873 and 1930 the mortar probably includes lime and sand mixes augmented with Portland cement. Original construction techniques offer clues on how to maintain the home’s original appearance if that’s your goal.

Strength and permeability (rate of vapor transmission) as well as a visual inspection of the old mortar will show the tuckpointing professional what kind of mortar mix and techniques should be applied. There are exceptions, but the mortar on homes dating from the mid-1950s on have a fairly homogeneous texture and color.

Identifying the sand and color allows the tuckpointing contractor to match or come very close to matching the original mortar. Sand is the largest ingredient by volume and is what gives mortar its color. If necessary, modern pigments can be added to the mortar at the job site.  Mortar should be measured and mixed carefully to assure visual and physical characteristics.

Matching the chemical properties of the original mortar is not necessary. As long as the new mortar matches the original in color, texture, tooling and sand used, it’s a good result. Components of historic mortar (before 1930) varied a lot because they were made of natural materials. Modern mixes are manufactured so they can be standardized and easily replicated.

Prevent Damage

To prevent damage and ensure proper masonry restoration, replacement mortar should be softer or more permeable than the masonry work. And it should be no harder or more impermeable than the original mortar. If the joint is properly prepared, a good bond forms between the new mortar and the adjacent surfaces, strengthening the structure.

What to Avoid:

1. Masonry cements at hardware stores are not recommended for older homes because they produce too strong of mortars that can damage historic masonry.
2. Modern chemical additives may have detrimental effects on historic masonry. Antifreeze compounds may present salts that lead to efflorescence.
3. Power tools in the hands of unskilled tuckpointers can result in damage. Specialized automatic tools used in conjunction with hand tools by a skilled craftsman will reap the best results.

Mortar joints in homes are called the wall’s “first line of defense.” To maintain the structure and appearance of the home tuckpointing should be completed approximately every 20 to 30 years.  The right tuckpointing mortar in Chicago older homes ensures a successful masonry restoration by protecting the visual and physical integrity of the masonry.