On 9 June, 09:08, Tim Lamb wrote:
Is there a recommendation for the maximum roof area to be drained by 4"
plastic gutter?

Building regulations were a distant dream when my Victorian barn was
built and the twin down pipes discharge through shoes onto the narrow
strip of verge next to the lane. There has been some local subsidence of
the foundations as a result.

I am currently building a single story *end* extension and will make
provision to pipe collected rainwater to an existing surface water
system. However, underground piping from the original down pipes is not
practicable.

Could I route the barn water along the new gutter without annoying
building control? The total area drained would be 35m2 in plan.

regards
--
Tim Lamb

I looked into this very recently but blow me I cannot find the
websites I found a week ago, but they are there. I thought the
pavingexpert site had details but seemingly not. It might well have
been one of the suppliers of guttering that was helpful.

You will need to hunt the details up with an appropriate search. One
of the factors is whether the guttering has a fall on it not - factor
of about 2:1 !! If my memory is correct something like 60m^2 if there
is a fall. I know that my 35m^2 is well within spec for the change in
direction I want to do but I will have to adjust the slope. I will
however have to do a 1m^3 rainwater SUDS tank.

Rob

I would be chary about involving the BCO as he will insist on you
putting in an appropriate soak away.