The message
from (Rodger Whitlock)
contains these words:

One important difference, however, between the load that roofs
are designed for and the load imposed by plant pots, grow-bags,
and such: the latter are a permanent load, whereas snowloading
(the only real weight a roof takes) is transient in temperate
climates, coming and going through the winter. (Heavy snowfall
areas have steeper roofs than low snowfall areas, so the load is
simply shed to the ground.) A load that causes no damage in that
time frame may produce significant settling and warping after six
months or a year or so.


--
Rodger Whitlock
Victoria, British Columbia, Canada
change "invalid" to "net" to respond

The loading you describe is factored down after 30 degrees pitch. Once
it gets to about 55 to 60 it`s practically negligable. However, at 22.5
degree the load is approximately equivalent to 10ft of snow (it dont
happen in england). God knows why they decided to have the load so great
but thats code of practices for you. It`s classed here as a medium term
load and thats the one that timber is designed to and not long term
loadings. All fixing requirements are taken for the reaction in medium
term and not long term.

Interesting subject and you`d have thought that flat roofs would be easy
to design. In fact, they are some of the hardest ones.

--
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