Overview

Arrowhead Lake is a private community located in the scenic Poconos of Pennsylvania. In 2011, a new Adirondack-style community lodge was constructed in the development. The timber-frame building houses a fitness center, billiards room, library and lounge, a lakefront patio and hosts year-round community events.

The Arrowhead Lake Community Association (ALCA) became concerned when they noticed evidence of horizontal cracking in the timber trusses and glue laminated beams in the banquet, lobby and great rooms. Cracking was also occurring in the mechanical and restroom concrete floors as well as the exterior loading dock. In addition, the Association had questions about their mechanical systems and the capacity of their emergency generator. ALCA engaged Entech to provide engineering services for structural, geotechnical, mechanical and electrical investigations for the Lodge.

A limited structural assessment addressed the cracked trusses and beams in the main rooms. A geotechnical investigation was completed to determine the cause of the cracked concrete floors and loading dock. A mechanical investigation reviewed the existing systems to make recommendations to better control the environment in the exposed truss areas and an electrical system analysis was completed for systems connected to the emergency generator.

Structural
Entech determined that the cracking in the trusses was due to excessive humidity and temperature conditions – particularly in the winter months when warm air rises to the ceiling, drying out the beams. Low velocity fans were recommended to cool the area around the tresses while not disturbing the air for occupants in the effected rooms. Since the building is kept fairly warm, resulting in low relative humidity, it was recommended that humidifiers be added which would be engaged when the heating system is in use.

Geotechnical
The Geotechnical investigation revealed that settlement of the building was due to fine-grained soils being eroded due to a fluctuating water table. The relatively high design bearing pressure of the building (4,000 lbs per sf) was directly influencing the settlement.

Entech recommended that control points surrounding the building be used to determine the magnitude of future settlement. In addition, depending on control point monitoring, the geotechnical consultant recommended that underpinning (transferring foundation loads to more competent bearing stratum) could prevent further settling of the building.

Mechanical
The mechanical evaluation revealed that not all systems were being controlled at optimal levels. Temporary adjustments made in the main controls of the system were overriding programmed settings. It was recommended that any short-term temperature adjustments be made at the room thermostats rather than in the main controls, allowing the system to revert back to programmed settings with the next regular cycle.