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Running gutter downpipe horizontally over a felt flat roof.

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Rednadnerb

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Dec 14, 2021, 12:22:33 PM12/14/21
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as above. I need to divert a gutter downpipe over about 5m of a felt flat roof into a different drain.
My best guess would be to have downpipe clips fixed to ply pads that just sit on the felt roof. Would that be the best way to do it?

Martin Brown

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Dec 14, 2021, 12:32:23 PM12/14/21
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On 14/12/2021 17:22, Rednadnerb wrote:

> as above. I need to divert a gutter downpipe over about 5m of a felt flat roof into a different drain.
> My best guess would be to have downpipe clips fixed to ply pads that just sit on the felt roof. Would that be the best way to do it?

It needs some minimal angle of slope or the thing will fill up with
leaves and mud often enough to be a real nuisance. I have no idea what
building codes say but you might be better off running a length of wide
gauge guttering from the down pipe to wherever the water has to go.

Even short going around the weatherboard bits of pipe at 45 degrees
sometimes gum up with bits of fallen roof mortar and leaves so any pipe
at a shallower angle & 5m long stands no chance of working for long.

--
Regards,
Martin Brown

Nick Odell

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Dec 14, 2021, 12:34:30 PM12/14/21
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Is there a gutter around the flat roof? My back gutter comes down
from the main roof and then empties into one corner of the gutter that
runs round all three sides of my porch. The combined output of roof
and porch then pours down the drain on the opposite side.

Nick

Rednadnerb

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Dec 14, 2021, 12:46:42 PM12/14/21
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That is how it is and the flat roof gutter can't cope with the rain in a heavy downpour.

Rednadnerb

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Dec 14, 2021, 12:47:10 PM12/14/21
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Thanks Martin, that is a very good point.

williamwright

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Dec 14, 2021, 1:02:51 PM12/14/21
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On 14/12/2021 17:22, Rednadnerb wrote:
> as above. I need to divert a gutter downpipe over about 5m of a felt flat roof into a different drain.
> My best guess would be to have downpipe clips fixed to ply pads that just sit on the felt roof. Would that be the best way to do it?

The pads should be concrete or brick. Ideally, get some 600x600x50
paving slabs and cut them into four. Stand each one on a sand bed. Put
some fall on the pipe. Maybe use guttering instead of pipe.

Bill

Nick Odell

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Dec 14, 2021, 1:46:33 PM12/14/21
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On Tue, 14 Dec 2021 09:46:39 -0800 (PST), Rednadnerb
<bhar...@hotmail.co.uk> wrote:

>On Tuesday, December 14, 2021 at 5:34:30 PM UTC, Nick Odell wrote:
>> On Tue, 14 Dec 2021 09:22:31 -0800 (PST), Rednadnerb
>> <bhar...@hotmail.co.uk> wrote:
>>
>> >as above. I need to divert a gutter downpipe over about 5m of a felt flat roof into a different drain.
>> >My best guess would be to have downpipe clips fixed to ply pads that just sit on the felt roof. Would that be the best way to do it?
>> Is there a gutter around the flat roof? My back gutter comes down
>> from the main roof and then empties into one corner of the gutter that
>> runs round all three sides of my porch. The combined output of roof
>> and porch then pours down the drain on the opposite side.
>>
>> Nick
>That is how it is and the flat roof gutter can't cope with the rain in a heavy downpour.

I wonder where you are located? I'm in "Wet" Yorkshire and we
certainly get more than our fair share of rain around here.

What I didn't mention before is that my gutters actually drain two
main roofs. We are on a terrace down a steep hill and the downpipes
are shared between two houses. The gutter from the house uphill from
me drains through a short pipe into the end of my guttering and then
all the water comes down the downpipe at the other end. They seem to
cope. Could there be some other problem with your system?

Nick

Andrew

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Dec 14, 2021, 1:50:07 PM12/14/21
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The problem with using a section of gutter is keeping it in
place during strong wind. You might want to position some
1/2 building blocks at 1 mtre intervals, laid flat and make up
some sort of upstand to connect the gutter brackets to,
also taking account of the gentle fall needed.

Rednadnerb

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Dec 14, 2021, 2:10:36 PM12/14/21
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>
> What I didn't mention before is that my gutters actually drain two
> main roofs. We are on a terrace down a steep hill and the downpipes
> are shared between two houses. The gutter from the house uphill from
> me drains through a short pipe into the end of my guttering and then
> all the water comes down the downpipe at the other end. They seem to
> cope. Could there be some other problem with your system?
>
> Nick

I think there were originally two separate downpipes and two drains and the builders of the flat roof kitchen extension diverted one into the other and now it can't cope in a heavy downpour.

Tim Lamb

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Dec 14, 2021, 3:01:47 PM12/14/21
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In message <30e8448e-30e2-406d...@googlegroups.com>,
Rednadnerb <bhar...@hotmail.co.uk> writes
6" gutter and 4" down pipe? Bit agricultural for a domestic application
perhaps.

--
Tim Lamb

Rod Speed

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Dec 14, 2021, 3:43:53 PM12/14/21
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Rednadnerb <bhar...@hotmail.co.uk> wrote

> as above. I need to divert a gutter downpipe over
> about 5m of a felt flat roof into a different drain.
> My best guess would be to have downpipe clips
> fixed to ply pads that just sit on the felt roof.

I wouldn’t because it would sag between the ply pads.

> Would that be the best way to do it?

I'd not use ply pad and fix the clips thru the felt roof
to the timber under that. Not so easy to do tho.

Rod Speed

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Dec 14, 2021, 3:50:53 PM12/14/21
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williamwright <wrights...@f2s.com> wrote
> Rednadnerb wrote

>> as above. I need to divert a gutter downpipe over about 5m of a felt flat
>> roof into a different drain.

>> My best guess would be to have downpipe clips fixed to ply pads that just
>> sit on the felt roof. Would that be the best way to do it?

> The pads should be concrete or brick. Ideally, get some 600x600x50 paving
> slabs and cut them into four. Stand each one on a sand bed.

Still going to sag between the pads.

> Put some fall on the pipe. Maybe use guttering instead of pipe.

Yeah, pipe on a flat roof is going to block up with leaves if there are many
of those.

Peeler

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Dec 14, 2021, 5:13:10 PM12/14/21
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On Wed, 15 Dec 2021 07:50:44 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

<FLUSH the abnormal trolling senile cretin's latest trollshit unread>

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Peeler

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Dec 14, 2021, 5:14:04 PM12/14/21
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On Wed, 15 Dec 2021 07:43:45 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

<FLUSH the abnormal trolling senile cretin's latest trollshit unread>

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williamwright

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Dec 15, 2021, 12:40:51 AM12/15/21
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On 14/12/2021 20:50, Rod Speed wrote:
>> The pads should be concrete or brick. Ideally, get some 600x600x50
>> paving slabs and cut them into four. Stand each one on a sand bed.
>
> Still going to sag between the pads.

For a 5" pipe I'd put supports every two foot.

Bill

Rod Speed

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Dec 15, 2021, 1:12:31 AM12/15/21
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williamwright <wrights...@f2s.com> wrote
I wouldn’t bother with supports, have the pipe directly on the flat felt
roof.

Better still an open wide gutter so the leaves can be removed if a problem.

Peeler

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Dec 15, 2021, 4:23:04 AM12/15/21
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On Wed, 15 Dec 2021 17:12:21 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

<FLUSH the abnormal trolling senile cretin's latest trollshit unread>

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Brian Gaff (Sofa)

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Dec 15, 2021, 5:45:56 AM12/15/21
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I'd have a gentle slope in the pipe by having stand offs of differing sizes.
One tends to get crud from the gutters building up in the horizontal bit
otherwise.
I used to see a lot of clever ideas, even a second gutter along the edge of
the flat roof and the downpipe feeding into that, or course no telling what
constitutes flat, since you need a slope or you end up with a roof lake.
Brian

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newshound

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Dec 15, 2021, 5:57:38 AM12/15/21
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+1 for gutter, and that seems an excellent idea to me. Also, easy to
move if the felt needs replacing.

Tim Lamb

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Dec 15, 2021, 7:35:25 AM12/15/21
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In message <spch0v$v5d$1...@dont-email.me>, "Brian Gaff (Sofa)"
<bri...@blueyonder.co.uk> writes
>I'd have a gentle slope in the pipe by having stand offs of differing sizes.
>One tends to get crud from the gutters building up in the horizontal bit
>otherwise.
> I used to see a lot of clever ideas, even a second gutter along the edge of
>the flat roof and the downpipe feeding into that, or course no telling what
>constitutes flat, since you need a slope or you end up with a roof lake.

Upthread, the OP says the flat roof gutter is overwhelmed in heavy rain.
Could the problem be insufficient fall on the new flat roof gutter or
downpipe obstruction due to leaf filter etc?

--
Tim Lamb
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