Preservation Structural Report

Max Ferro, an historical architect, advised us to acquire the services of experienced engineers, one of these being Arthur Macleod, a structural engineer.  He and Max have considerable experience with historic buildings and each have impressive resumes (see the biography of Max Ferro on the Historical Architect page ***future link).  Max coordinated with the engineers, reviewed their reports, and also supplemented the reports with further comment regarding specific issues.

 The review by Arthur MacLeod, structural engineer, included a lengthy building inspection and a review of structural plans which needed to be photographed in their archived location in Boston. The report makes detailed observations of the building envelope, which includes the roof, masonry, and windows, and of the structure which includes the framing structural members of the building. There are too many observations and recommendations to briefly summarize, but there are some key points that should be highlighted.

tower drawing med

tower drawing 2

tower top

Tower Needs

The report addresses concerns regarding the tower. Additional structural ties are recommended to be added to support the fleche (the highest portion including the roof). A design recommendation is included in the report. There is also the recommendation to add ventilation to the tower in order to reduce condensation from forming on the inside walls, which causes moisture problems.

There are open joints in the tower granite, especially in the corners, and the inside brick lining of the tower is wet, doubtlessly due to both condensation and flashing leaks.

tower interior

We need to go from reacting to emergencies to doing some advanced planning with suitable engineers, as we are now proposing.  Max recommends studies be done by a mechanical engineer and also an electrical engineer’s study is needed.

The central steeple (more correctly termed a fleche) which has massive weight, rests on the brick of the outer tower walls. Mr. Macleod has recommended for the tower: Steel Reinforcement. Provide tie rods at the transfer beam level to resist thrust forces at the window arches. In his report he specifies further details as to exactly what is needed.

Marble Divider shorter

Buttress Issues

Max Ferro, our historical architect, has been looking at historic buildings for nearly forty years, and he is concerned about the buttresses, which help to resist the thrust of the roof. Buttresses are a notorious problem in almost every Gothic church. Yours, unfortunately, have somewhat greater problems than the usual wind and weather exposure on three sides.

buttress 1 sm

buttress 2 sm buttress 3 patches

The roof or cap of each buttress, itself a coping stone, needs the same through-wall flashing underneath, which it does not have. With the long wall behind each buttress expanding and contracting much more than the buttresses themselves, such joints fail it is obvious by observation that the buttresses are full of water and are breaking apart from the main wall. Even stalactites and stalagmites have formed as in wet caves, and forming such deposits takes constant dripping over many years.

Corner buttressW buttress+tower

Corner buttresses

While it would be good to find a simpler answer, Max suspects we will need to take down at least one buttress and rebuild it in order to assess the exact scope of the present damage.

 

Marble Divider shorter

Water Issues

Typically the water that leaks into the structure then evaporates in the cavity space where furring supports the plaster. However, excessive water leads to interior problems as we see in our church. The report summarizes other possible sources of excessive leaking including the coping, flashing, and the window trim. There is no one single source to blame for the leaks, but a combination of various sources. The report makes detailed recommendations to waterproof the building.

coping drawings sm

Marble-Divider

buttress 4 corner

corner

Coping/Capstone Issues

Coping is the capstone that keeps water out of the top of a masonry wall. All masonry walls, both brick and stone, have two or more layers, called withes. In this church the inside is brick, which is the main support of the walls, and is covered with granite on the exterior. The method of coping used was, instead of the preferred method using copper with bronze dowels (used by the ancient Greeks, which remains waterproof practically forever), the budget alternative using sticky sheets of tar paper was used, waterproof when installed, but, unknown to those in the early 20th century, that it would break down chemically in less than 30 years. The church walls have been filling with water ever since the early 1930s. Photos show the pattern of cracked and open joints through which water has flowed. Repair records that go back to 1946 include endless repointing, but if the water is entering the wall at the top, between the coping stones, all that repointing did is keep the water hidden inside the wall until the damage was extensive. All coping stones need to be temporarily lifted and then replaced over through-wall metal flashing.

Marble Divider shorter

 

Voussoirs and Other Water Issues

Voussoirs are the wedge-shaped stones that form an arch and the central voussoir is called a keystone. 

capstone

Here, for example, is the voussoir above the door to the Mary Baker Eddy room.

The issue is the connection with the wall that needs pointing of the vertical joints and to press down into each fresh joint a soft lead “T”-cap, hammered flat to protect the joint. A certain vulnerability still remains due to a lack of flashing.

Once water is inside a building, it becomes exponentially more difficult to deal with. One must find the source of the leak outside. But the source may be very far away, with water flowing inside hollow walls and ceilings to emerge in unexpected places.

 keystone sm

Marble Divider shorter

 

Clerestory NClerestory SClerestory Roof Issues

The clerestory roofs are at both the North and South side of the church.  Looking back over years of repairs, it is obvious there is a major problem with these two clerestory roofs.  They have been repaired often and the source of the problem is the ice that plummets down from the roof above piercing the slate roof below.  The ceilings have missing plaster pieces not yet repaired due to the need for a permanent solution to this recurring problem.  Holes in the roof have been patched and damaged slates have been replaced. 

The winter of 2013-2014 was especially problematic with one Wednesday evening meeting being disrupted with water leaking in from a damaged area in the clerestory roof from falling ice.  Large plastic sheets were hung to catch the water and prevent damage to the cushions or wooden pews.  Needless to say the meeting was a little on the loud side with the plastic sheets amplifying the sound.  Actually, though, we found the experience to have its rewards.  Before the meeting a small band of faithful members came swiftly to help with buckets and plastic sheets and one member sat nearby to keep an eye on the buckets lest they overflow.

Max Ferro and the structural engineer have recommended wooden roof reinforcement, covered with copper, and then shingled with strong and flexible fiberglass shingles.  This would create a relatively permanent solution to this recurring problem.  This, solution, however is quite expensive, but is one of our priorities.

 

Repair Principals

Systems and components must meet safety codes and durability standards and should conform to an aesthetic consistent with good preservation practice. In general, the work should meet the guidelines for preserving this building under The Secretary of the Interior’s Standards for the Treatment of Historic Properties and as accepted by the Church.

 Marble Footer shorter