Historical Facades and Wall Bracing
Isaac Blair’s experience with historic, landmark structures is far reaching and comprises the majority of its work load. The company’s depth of experience is a valuable asset which allows for decisive responses to crises and for designing the best and most comprehensive solutions. For example, Isaac Blair shored the oldest fire station in Boston, the Eustis Street Fire Station. The building was nine inches off plumb and was jacked back into position incrementally over a period of one year.
Buildings of a certain age give Boston a unique architectural charm but they do show their cracks as the structures age. Foundation failures are common among older structures and Isaac Blair has performed emergency as well as planned shoring work to correct and install new foundations. The stone rubble foundation of an historical barn in Cambridge failed and was visibly sagging. Isaac Blair raised the structure so a new foundation could be installed.
Roof Trusses Failure
Roof truss failures occur for various reasons including when snow loads are heavy and cause a roof to deflect or when rotting roof timbers cause a structure to sag. To minimize damage and prevent further failure, Isaac Blair shores the interior of a structure so that equipment and materials can be safely removed and repairs can be made.
When support columns need replacing, Isaac Blair is often brought in to install needle shoring to support the existing roof structure to allow for column replacement. In the photo at right, Isaac Blair installed shoring towers around 24″ square wood columns on the basement level of a 10 story building, directly below a jacking system on the first floor. The existing columns were being replaced by narrower steel columns.
Needle shoring and double needle shoring is used to create large openings or passageways where none previously existed. Isaac Blair has installed needle shoring on a range or projects in the commercial and industrial sector as well as for the renovation of private residences. During the construction of the American Wing of the Museum of Fine Arts for example, Isaac Blair provided needle shoring to support wall openings created between the existing museum and the new wing. Four of the openings were 22 feet wide with the wall thickness at three and one half feet.
Isaac Blair has performed remediation work on an array of building types, most of which are cultural, historical and civic attractions. In Gloucester, MA, Isaac Blair provided shoring of the Town Hall bell tower that was beginning to crack. Officials were concerned that the tower could fall inward, damaging historical items on display in the building. Isaac Blair relocated the items, shored the bell tower for repair work, then returned all historical items to their original location.
Isaac Blair has occasionally been brought in to assist in remediation projects so others could perform the necessary abatement work. A basement furnace oil spill at a private residence required Isaac Blair to lift the residence so the contractor could abate soil contamination. Isaac Blair shored the structure in such a way to allow the resident to stay in the home while the work was conducted.
Calibrated Jacking and Emergency Work
Isaac Blair frequently responds to calls for emergency shoring for a variety of reasons including damage caused by car crashes, building failures during renovation and age-related structural failures. At Boott Mills in Lowell, MA, the existing piers that supported the mill building were compromised. Once the water supply to the canal was shut off and the canal emptied, Isaac Blair installed shoring beams so the piers could be repaired. Isaac Blair installed load cells on top of the screw jacks so a digital readout of the amount of pressure delivered was readily available.