Quote Originally Posted by andy
Iam confused abut putting polycarbonateon the roof my slat house.the polycarbonate supply state the material lets 20% light how do I figure what shade cloth i need to achieve a 50% shade for my vandas and cats.
to work out the shade cloth needed to get to 50% shade when using polycarbonate with a 20% rating as a start :-

no shade = X,lets say 100

we are wanting to get 100 / 2 = 50

100 - 20% = 80

shade cloth comes in 25-30%,50% and 70-75%

25% of 80 = 20
30% of 80 = 26
50% of 80 = 40
75% of 80 = 60

so 80 - ? = 50
so 80 - 30 =50
from above it can be seen that there is no shade cloth that has the percentage that we require.

I would personally go to the 50% in this case as it is better to have slightly less light than what would be the ideal of 50%,which would give us 60% shading where as 30% would give us 46% shading