1850 Alice – Overcoming Challenges
By Stanley Coventry | December 7, 2022
Washing windows. It sounds straight forward – grab a squeegee, a bucket of soapy water, and start washing. Now how about washing windows on the outside face of a 12-story building? Things tend to get a little more complicated.
The best time to implement a safe method of washing windows for a large building is prior to construction. A thoughtful exterior building maintenance (EBM) plan will ensure that the maintenance can be completed, both the equipment and building have been designed to support the load and, most importantly, the workers go home safe at the end of their shift. However, in many cases, an older building will not have had an EBM plan incorporated from the start.
That was the case for 1850 Alice, a concrete building constructed in 1962 overlooking Lake Merritt in Oakland, California. D.H. Charles was hired on as a consultant to help with the structural design of the building and the proposed EBM equipment. The variety of equipment for washing these windows and maintaining the exterior of the building consisted of tie-back anchors, outriggers, guardrails, and horizontal lifelines.
Tie-back anchors secure fall protection equipment to protect the workers in case of a fall. Typical tie-back anchors, and the structure that supports the anchors, must be designed to hold a 5,000-pound load applied in any direction. To put that load in perspective the curb weight of a Ford F-150 ranges between 4,000 to 5,000 pounds. Just one of the handful of fun challenges with this project was that the roof slab was only two inches thick, much too thin to support any considerable load. It was also imperative to avoid having equipment protrude into living space below the roof. To eliminate any expensive retrofit work of the building we were able to thoughtfully locate the anchors so that they could be installed directly to roof joists below with concrete adhesive anchors. This avoided loading the thin concrete slab all together, and the need for equipment or anchorage extending below the roof.
At DHC we don’t just like to solve engineering problems, we also like to solve problems our clients’ may face. While drilling for the adhesive anchor rods for the tie-backs, the contractor had multiple areas where they ran into rebar right where the anchor rods needed to be installed. With our in-depth experience we were able to quickly give the contractor guidance on re-positioning the anchors in the field and repairing the un-used anchor holes to their original capacity. OSHA requires that EBM equipment is tested prior to being placed into service. The contractor also ran into a small issue with being able to test the equipment in the field. Once again, we were able to provide our expertise to come up with another way to test the equipment and ensure it is safe to use.
Designing EBM equipment for existing structures can create many challenges such as only having access to limited as-built information of the building and needing to find creative methods for getting older and weaker structural members to support the required loads. However, at DHC we look forward to the challenges of designing EBM and fall protection equipment, and with our extensive background in the industry we take on these challenges effectively and efficiently.