The damaged area has now become the strongest area. Rotten wood is now encased within a square tube of fabric soaked in cement and acrylic.
This test roof has proven the longevity and strength of woven plant fiber as reinforcement for a cement and acrylic roof. This edge design used here for repair is similar to the edge of the three year-old shed roof, which so far shows no indication of any problems. This repair has made the rotten wood edge so strong it is beyond human strength to flex. Judging by the ageless feel at the ridge, the repair has added many years to this first test roof.
End notes :
(1) The ferrocement legs (above left) are cement and steel around a foam core, they are a similar test of design as the fiber surrounding rotten wood and were built about eight years prior to this test.
(2) For comparison, I encased rotten wood stairs with ferrocement in the late 1970's, I have not heard of any problem with this repair.
(3) The end of the larger test roof was repaired three years before the photo below. This end was constructed with a single layer of burlap, it was purposefully built as a non-supporting curtain wall so that the roof planes could be observed through time without support. The larger roof is easily carried by four people but is quite heavy, the end was continuously tested by visitors and soon needed repair from repeated attempts to lift the roof from the end.
Part of the problem with this second test roof was the fabric sagged under the weight of fresh wet cement and created a depression that collects water and leaves. This created an unplanned experiment that proved neither rotting leaves nor periodic freezing and thawing of the standing water is detrimental to the membrane. It is the geometric curve upward that is of insufficient strength for winter snow load and has caused gradual failure of this roof along weight bearing edges.
I repaired the broken corner pictured below in my usual auto meditative mode and was quite surprised to discover the optimum strength reinforcement resembled a human hand. This led to sculpture projects the following summer and the ferrocement.com sculpture manual the next winter.
