Abbot Restores 3-Story Apartment Complex in Boston's Dorchester Section

Phase 1: Rear Wall of Building 

Abbot recently completed restoration of a the facade of a 3-story brick apartment complex with an elegant center courtyard located at 466-468 Columbia Road in Boston's Dorchester section. Since the building was converted to residential use approximately 30 years ago, the brick masonry in the front and rear of the building had experienced severe weather related deterioration. The owner had the building evaluated by an engineering consultant (RMX Northeast, Milford, MA), and a scope of work was developed to correct all of the deficiencies. Abbot was awarded the restoration contract following a systematic bidding process.

The project was accomplished in two phases, with Phase 1 addressing the rear wall of the building. During its initial investigation, the consultant observed that the brick used on the rear wall was made from a soft white concrete material that was commonly used during that period of construction.  

After an extensive evaluation of the surface condition, it was determined that a high level of repair was needed. Two options were considered: application of a stucco material over the existing surface or installation of a vertical metal panel system. Although the metal panel system was a more expensive option, the owner decided that this technology would be a more permanent solution and the metal paneling would not warrant the ongoing maintenance that the stucco would require. PAC-CLAD (.040 mill), manufactured by Petersen Aluminum (Elk Village, IL), was selected as the metal panel system. Not only does this system provide an attractive physical appearance but its energy efficiency would provide long term cost savings.

A critical component to the successful installation of PAC-CLAD system was proper surface preparation. First, Abbot carefully furred the brick walls to create an even surface. Then, weatherproof exterior plywood was mechanically anchored to the furring. A Tyvek air barrier was applied over the plywood, and the metal paneling was installed. Significantly, Abbot was able to meet the challenge of installing the paneling behind the fire escapes and around the windows to complete the professional installation.

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In our next issue, we will describe Phase 2 of this restoration -- the front and sides of the building.

Tuckpointing: A Critical Task in the     Maintenance of Brick Masonry 

In many of our Case Studies, we describe how we have done a complete "repointing" on the façade of a brick masonry building. "Repointing", or "tuckpointing" as it is more accurately called, is a precise, labor-intensive process that involves removing and replacing crumbling and missing mortar between stones, blocks and bricks. Tuckpointing provides a strong, waterproof mortar joint that matches the appearance of the original mortar and will extend the serviceable life of the masonry building.

Tuckpointing is a critical maintenance task that prevents water from entering the brick wall cavity. If water is allowed to get past the mortar and into the wall, brick failure  such as cracking or spalling (popping off of the brick face) may occur. Tuckpointing prevents further deterioration due to moisture penetrating the failing joints and compromising the entire structure. The term "tuckpointing" is derived because the mortar is "tucked" into the damaged mortar joint with the point of a trowel called a "pointing trowel."

The first step in a successful tuckpoint repair to remove the existing mortar. This is typically achieved by utilizing a state-of-the-art grinding system with waterless diamond blades connected to dustless equipment. As a rule of thumb, mortar removal is to a depth of 2-1/2 times the width of the joint to a minimum depth of 1/2 inch.   

The next step is to determine the specific type of mortar used in the original wall construction. It is important to determine the age of the building to be tuckpointed. For buildings constructed in the early 1900s or prior, proper care and research must be used in selecting the repair mortar. It wasn't until after the 20th Century began that portland cement was combined with the traditional sand and lime to make mortar.

To avoid irreparable brick damage, the compressive strength of the repointing mortar should be similar to or weaker than the compressive strength of the original mortar. Under load, a stronger repointing mortar will deform less than a weaker original mortar, causing the load to be concentrated on the thin strip of stronger repointing mortar. This stress concentration can lead to spalling of the brick face. The brick masonry is loaded by its self-weight and any externally applied loads. In addition, the brick masonry is subjected to internal loads due to its thermal expansions and contractions and the shrinkage of the repointing mortar.