We've all observed, first-hand, the impact of a leaky roof on the sanctuary below. But what's causing all this? How big are the leaks up there, on the roof?
We are so glad you asked! Your GLC council commissioned several roofing vendors to do an assessment of our leaking roof, and below are some of the most insightful photos they captured. We found a few gaps that are wide-open, and letting water in. But we also found a lot of issues due to the use of incompatible building materials... which cause rust and quicker deterioration.
The "flashing" around the edges of the roof is our main concern. The metal sheeting beneath the tiles should curve up the surrounding walls to create a water-tight seal. In this case, we see some corrosion of the flashing, loose tiles, and an awkward repair attempt using caulking. This is above the Luther Seal window, on the south side of the sanctuary.
This is a gap in the roof joints directly above the choir and organ. We are seeing a crack in the historic metal flashing, which has been inadequately repaired using caulk. This didn't work -- the metal flashing expands and contracts during the seasons, which the caulk cannot do, and this makes the hole even larger. The correct solution should have been to replace the cracked flashing entirely.
The galvanic reaction: the church's original flashings and gutters are copper, which you see oxidized to a greenish color on the right. In the center, flashings were inexpensively replaced at some point with galvanized steel, which rusts and turns orange. These two elements react in the presence of water, degrading each other. The caulking you see is a temporary fix. The hole on the left probably isn't helping either.
Although your council leaders have been aware of some issues with the plaster in the sanctuary for some time now, additional moisture incursion during the winter and spring of 2018-19 seem to have made matters much worse.
What's causing this? We're not 100% sure -- we know that the issues we are seeing are confined to a few specific places on the roof, namely the "parapet walls," or the places where slanted sections of roof join up to a stone wall. There are four parapet joints: above the altar, above the Luther window, above the Luther Seal window, and behind the choir and organ. We're seeing damage in all four places. The damage could be due to ice buildup, deterioration of the roofing materials, use of sub-standard caulking for cheap-and-easy repairs on a historic roof, or other factors we don't yet understand.
Haven't we maintained our roof? Yes! GLC had the sanctuary roof entirely replaced in 1995 by a reputable roofer. But we're not seeing any issues with most of the roof: just the flashings and water-tight joints around the edges. That said, your GLC council did forgo annual roof service visits in 2014-16 due to budgetary challenges at the time, which may have allowed conditions to worsen.
So, could the roof collapse? No. The stone walls and roof joists and rafters of our 1914 sanctuary are intact and have not been compromised. What we are seeing are leaks in the outer roof... and their after-effects in the walls below. We need to re-seal the roof so that no water can enter, and then we will rebuild the plaster inside where it has deteriorated and discolored.
See photos below, taken in March 2019.