More on Roofs, greening, homeowners

Chris asked me if I had considered a white roof. Yes, I did. But first, consider that there are two subjects here: one is replacing the existing roof covering when it is past its prime, the other is adding something like plant sedums in trays on top of the existing flat roof.

The 100,000 sq ft warehouse I view from my 3rd floor windows was redone two years ago in white. Very reflective. I know white shingles on a sloped roof have a drastically shorter life than black shingles, I dont know if a white flat roof is any shorter lived. If I have to redo my flat roof (coming up in the next year or two, or so I have been saying for a few years ....) I will certainly do it in white or green (better to look at). However, sedum in shallow pots has way more benefits ... its very cooling, its green, absorbs rainfall, and it shades the tar roof itself and effectively doubles or triples its life because sun exposure is the principle cause of roof deterioration.

I am also getting an evaluation of my roofs done for PV solar, unfortunately the best sloped roof already has a big dormer on it and a bank of six skylights, thus reducing the area available to put roof PV up; but I could also put them on the flat roof, even though it has a less ideal exposure (SE rather than SW) but it would be best to redo the flat roof at the same time which adds about 7k to the cost.

The roof is well able to carry the weight of the sedum trays etc as they weigh less than winter snow, so IF i took them all down each fall and laid them on the patio, the roof will hold the snow weight, but will it hold both the sedum and the snow if I leave the sedum up there? Unknown; and high risk too! Plus there is the logistics of putting up and down the trays twice a year.

The base of the municipal water runoff problem is that businesses or homeowners that increase runoff pay the same water /sewer charges as do firms that moderate the flow, like MEC or IKEA, ie there is no reward for the virtuous or punishment (cost) to the extravagant. So, Council should tinker with the pricing mechanism of sewers, not go imposing a green roof "solution" onto those classes of payers they feel are the least able to notice or object to being victimized by a discriminatory tax.

Regardless of municipal policies, my green roof interests are motivated both by environmental concern and my pocketbook: trade off the cost vs the benefits.