This past winter, a southeastern Pennsylvania school district contacted me with an interesting roofing situation, i.e. problem. One of their high schools had been suffering for years with very old roofing systems that had been in place well past their intended lives.
The roof systems were as follows: adhered EPDM single ply membrane on 70% of the area and smooth built-up roof (BUR) on 30% of the area, both installed over the original gravel surfaced BUR, which was directly on the tectum deck. The upper EPDM roof sections were approximately 25 years old and in very poor condition. In fact, these were the oldest EPDM systems I'd seen still in use! The upper BUR roof system was not in much better condition. Also, an infrared scan performed years earlier had revealed substantial moisture within the roof systems. The roofs on this long, linear wing or pod type school were configured with sloped sides into a central valley, hence the main reason for the exceptional longevity of the existing roof system (excellent drainage). This was the good news. The bad news was that the valleys had been leaking badly for years, and the water infiltration onto the roof system was continuing.
The District had been debating the future of this high school for many years, whether to tear it down and rebuild new, renovate, or abandon/close. Because of the lack of a long term commitment to the school, the facility suffered from a lack of significant funds for needed repairs and improvements. This uncertain future was a significant factor in our roof plans and mandated an inexpensive, short-term resolution (five to ten years).
Based on my initial, cursory assessment, the obvious solution was to tear off the existing two roof layers, repair bad deck as required, and install a new roof system. Code issues also seemed to dictate this solution, as a third roof system, i.e. another retrofit roof on top of the two existing roof systems, would not be allowed. Based on my review, I informed the owner such a tear-off and replace plan could could $1 million or more, depending on the new system desired. Obviously, because of the doubtful future of this facility, the owner preferred minimal cost solutions, and in fact had earlier indicated an interest in coating the exposed EPDM and BUR surfaces with one of the liquid systems available from various manufacturers. However, it was apparent to us the surface condition of the EPDM made doubtful the efficiency of any such liquid coating system.
After numerous discussion with the owner (and following our successful response to an RFP for consulting services), we proposed "coating" the existing roof system with a minimum thickness of sprayed polyurethane foam (SPUF) roof system. As a per-requisite to this recommendation, we obtained the approval of the local building code official to consider this a "coating", not a third roof system. The official consented, based on the existing roof structure and the extreme light weight of this proposed SPUF system. The owner agreed to solicit proposals for this system, but also still wanted to consider the liquid coating system alternative. Hence, we bid the project with two base bids, both with ten-year warranties. The project also included identification of current wet areas in the existing roof (by infrared scan) and removal/replacement of these wet materials. It is critical that moisture not be trapped in the roofing system. The resulting bids received in April 2003 supported our SPUF recommendation as the most cost effective solution, and the project proceeded in late June 2003. It was efficiently completed in approximately two weeks, another good feature, as other significant work was ongoing on the site.
For comparison purposes, following are the (approximate) significant numbers:
Total Roof Area = 120,000 square feet
SPUF Coating Cost = $300,000
Liquid Coating Cost = $420,000
Project Schedule: 6/24/03 - 7/7/03
( Note: Due to certain unique circumstance on this project, I adjusted the cost figures to better reflect the current market.)
The resultant roof system (now a layer of BUR, a layer of EPDM, and a "coating" of SPUF) provides this owner with a low-cost solution with a ten-year no leak warranty. Regardless of the plans for this school in the future, the facilities department will be relieved of a major ongoing headache chasing leaks in this scholl for the foreseeable future. SPUF is not the solution for every roof problem, but it can be a very cost effective alternative when properly researched, designed and installed, and it is very versatile in its applications. Based on my many years of PA school experience, I believe there are many districts that could benefit from such a cost saving approach, regardless of the planned life of the affected school facility.
Mr. Mowry is an Emeritus member of PASBO as well as the General Manager at Roofing Resources, Inc. and a member of the PASBO Facilities Management Committee.
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