On the other hand, any per-unit retain certificate (other than capital stock) which is redeemable only in the discretion of the cooperative association, or which is otherwise subject to conditions beyond the control of the patron, shall be considered not to have any fair market value at the time of its issue, unless it is clearly established to the contrary.
Composition roof lifeAsphalt shingles are rated at 20, 25, 30, or 35 years. The average roof life is 5 to 10 years less, depending on climate conditions in your area. The life of any asphalt shingle roof is effected if Algae and Mildew is allowed to grow on it.
20 Year shingles rarely last 20 years without leaks. In my area where it is very hot in the summer and exposed to a lot of sunshine in all seasons, 20 year roofs are good for about 12 years usually. There are maintenance things you can do to prevent leaks, but not a lot you can do about aging of the shingles.