How do I stop my conservatory roof going green?

Question

I have a conservatory with a clear polycarbonate roof. It very quickly goes green with algae/mold. How do I stop this happening?

Answer 1

To answer your questions in order: 1. Moss growth on roofs seems to me, as well, to be much more common than it was years ago, although I haven't been observing for quite 50 years the way you have. Changes in average roof pitch and acid rain may be two of the contributing factors in this phenomenon. Older homes, I think, have drier roofs (and, thus, less moss growth) because they tend to have steep slopes. Rain runs off such a roof quickly and the shingles dry in a hurry. Moss needs moisture to thrive and a dry roof simply doesn't provide this important condition for growth.

Roofs on more modern homes are generally pitched at shallower angles. (That seemed to be the trend, anyway, for quite a few years; but steep roof designs appear to making a bit a comeback.) These low-sloped roofs don't dry as quickly as steeper roofs. The shingles tend to hold moisture for a longer period of time, offering suitable growing conditions for mosses and lichens.

It is also worth pointing out that shade from overhanging trees and deteriorating shingles that retain water can encourage moss growth on a roof of any pitch.

Moss may also be getting a boost from acid rain. Just as it needs water to grow, moss requires an acidic soil or growing medium. Acid rainfall can provide this condition in soil, and on roofs. A horticulturist I know has been noticing an increase in mossy conditions in lawns recently and says this also may be a result of acid rain.

2. Moss can shorten the life of a roof by holding moisture against the shingles. Most older shingles are made with an asphalt impregnated organic mat that contains wood or other fibers. As long as the asphalt excludes water from the mat everything is hunky dory. But long exposure to moisture (a likely condition under a heavy growth of moss), can soak the mat, cause the fibers to swell, and eventually break the shingles apart.

3. The best way to get rid of moss that already has a toehold is probably to spray it with a commercial chemical such as De-Moss, made by Ortho. After the moss dies, it should be removed from the roof, if possible, to avoid a regrowth. Old, dead moss will hold moisture against the shingles as surely as will live moss, and the conditions can quickly become suitable for regrowth. A pressure washing and a light brushing can assist in this removal process, but you need to be careful not to damage the roof while cleaning it.

4. Several products have come on the market in recent years that claim to prevent moss growth on roofs. They are zinc strips that come in coils 50 or so feet long, and several inches wide. You slide the strips under a layer of shingles close to peak of the roof, leaving two inches of the metal exposed, nail it in place. They need to be placed every 15 feet up from the bottom to protect the whole roof and then nature does the rest. Rain and snow melts dissolve some of the zinc and send it down the roof where it apparently kills moss and fungus.

Answer 2

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RE:
How do I stop my conservatory roof going green?
I have a conservatory with a clear polycarbonate roof. It very quickly goes green with algae/mold. How do I stop this happening?

Answer 3

After cleaning very well then put copper strips on the roof hear the top. The rain will oxidize the copper and it will run down the plastic. Copper oxide is poison to the algae.

Works on many kinds of roof and has been used for over five hundred years.

Answer 4

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Answer 5

you must have trees or large bushes nearby....they don't go greennormaly without vegetation around ..i have to wash my roof with a broom with a long handle and i use hot water and a good dollop off flash or Mr muscle

Answer 6

spray diluted bleach over it

Answer 7

i wash mine with hose try that.

Answer 8

clean it more often.lol