Regularly blocked hopper

[Potatan]

Hi,

I live in a flat in a large regency house where the drainage hopper from the roof regularly blocks up with leaves/twigs etc.

Picture of front of house:

The entire roof space (maybe 20mx20m?) drains into leaded gulleys which then, as far as I can tell, empty into one hopper at the back of the house.

As you can see, there are many large trees at the property, and the hopper regularly becomes clogged with twigs/leaves etc. and it then overflows spectacularly and noisily for the duration of any rain storm or even light shower until the maintenance company go up and clear it out.

I'll try and post a picture of the hopper later, but in the meantime I'm wondering if there is a solution to this, other than calling the maintenance company every time it blocks? I've been trying to think of ways of creatively using chicken wire etc. but all the ideas I have would appear to shift the problem to elsewhere on the roof which could be more disastrous to the upper floor occupants.

Thanks in advance.

 

[Nige F]

when it overlows...does it pour out of a specific pipe ...there used to be overlows built in for the very purpose..as a warning. But I have a feeling these houses weren`t meant to be surrounded by trees, just a theory of mine .They stand "foursquare" and the garden is @ a distance . No one left to ask now though

 

[SurreyRoofingEstimator]

There is a product that may be what you are looking for, it's called the Hedgehog Gutter Brush, just do a google search and you'll find it easily

 

[noseall]

It sounds like a design issue to me, as if the current system is easily overwhelmed.

People often underestimate volumes of water, under the illusion that water is free flowing, relatively low viscosity so it will get away. I have seen many failed soak-aways and patio drains because of this misunderstanding.

Either bigger pipes or more pipes/spouts are needed.

 

[Potatan]

Okay, I now have the pictures - see below.

Nige F - the overspill is from the hopper itself, none of the pipes appear to be leaking (at least not noticeably compared to the torrent from the hopper during rain).

SurreyRoofingEstimator - thanks for the suggestion, but the roof drains into 18" or 24" lead-lined channels around the roof perimeter, with a two foot parapet all round on the outside - they'd have to be pretty big hedgehogs

Noseall - you're possibly right about it being a design issue, but as the roof and guttering were designed about 200 years ago, it's a bit tricky to change now.

Anyway, here's the hopper as viewed from ground level:

Untitled

• Potatan
• 22 Jan 2010
• 1

Close up of hopper (also indicating the height of the parapet - the hopper is roughly flush with the leaded gulley):

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• Potatan
• 22 Jan 2010
• 1

None of these pipes or the gulley are leaking, but it shows how complicated things can get further down :

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• Potatan
• 22 Jan 2010
• 1

Finally, this is what can happen if you have a regularly overflowing hopper cascading the whole surface area of a big regency house 40-odd feet down onto a small flat roof (this is the state of my bathroom 2 days ago when the ceiling collapsed):

Untitled

• Potatan
• 22 Jan 2010
• 1

The last picture is also why I am trying to find a better solution, or advice about hopper types and sizes, or better methods to prevent build up of debris in the hopper.

Many thanks.

 

[noseall]

Bigger hopper, bigger down pipes, more downpipes, me thinks.

 

[RedHerring]

.

the overspill is from the hopper itself, none of the pipes appear to be leaking (at least not noticeably compared to the torrent from the hopper during rain).


Noseall - you're possibly right about it being a design issue, but as the roof and guttering were designed about 200 years ago, it's a bit tricky to change now.

Anyway, here's the hopper as viewed from ground level

Are you confident that the pipes are not blocked?

Which hopper overflows, the upper one or the lower one? Because, as I see it the upper feeds into the lower after a couple of 90 bends. A favorite place for blockages.
If the original design was so in-efficient I think it may have been changed by now. Perhaps any additions may have caused the problem rather than the original layout.

 

[Potatan]

It's the upper hopper that overflows when it is clogged up. When it is clear, the water runs beautifully down the pipes and into the drains. The problem only occurs when the hopper is blocked with leaves/twigs (or in one case, a bit of old felt or plastic or something that one of the roofing contractors left behind).

 

[RedHerring]

Is this your responsibilty or that of your landlord?
1 Regular cleaning/clearing forays on the roof before the hopper gets blocked,
2 Some/several contraptions of chicken wire around the channels to catch the twigs before they reach the hopper,
3 Reduce the height of the trees,
4 Modify the flat roof to accomodate the torrent of water.

 

[Potatan]

Now that it's raining, I've grabbed a video. Note that this is very light rain - the whole thing looks more like Niagara Falls when it rains a bit more heavily:

http://www.youtube.com/watch?v=vgGR3SVKIRE

 

[RedHerring]

Back to Noseall's comment of design but not limited to design of rainwater goods.
Also design of all water into one hopper, design of garden to allow such twigs etc to reach the hopper, design of the roof to be subject to such torrent in cases of overflow, etc.

It's not doing the brickwork much good either. It needs to be sorted.

Back to my question: who's responsibility?
and to my previous suggestions.

 

[Nige F]

Bigger hopper, bigger down pipes, more downpipes, me thinks.

Indeed.. maybe a custom made lead one with a overflow spout , and a lid. and into a 110mm soil pipe . Can`t look any worse among that existing lot

 

[justlead1]

Hi. You mention drains, Can you lift a man hole and check flow and destination?
As i has come across a similar situation where a soakaway/water table could not cop with the discharge and the pipe backed up. Also the size of property / roof being served by one 4" outlet /hopper is more than stretched to the limits.
If you were to be up on the roof during rain and witness the amount of water trying to get through and into the hopper, it may help to find a solution. I must say i am amazed water has not backed up and in the property via the drips. Good Luck

 

[Potatan]

Thanks for all the suggestions and comments. The hopper was full with mostly moss, apparently, and there was more on the roof. The maintenance/management company were apparently supposed to sweep the roof twice a year, but this hasn't been happening. It will from now on (even though I don't think it's quite often enough, but it's a start).

Cheers

 

[ladylola]

Last year I worked on the roof at Caulke Abbey in Derbyshire where they had a similiar problem. Lead roof and once or twice in very heavy rains the outlets had blocked and water had entered the building by backing up through the lead drips (joints). As the building houses some valuable items the NT were keen for it not to happen again.
A survey decided that whilist the design was ok 200 years ago changing weather patterns and heavyer rainfall meant that at times the design would fail.
The end result was that we had to put in a new additional outlet and change the fall on several of the lead bays.
That's a pretty expensive way to go about your problem and whilist it would undoubtly work I would suggest that you follow the advice given by others and increase maintenance especially in the autumn when the leaves are falling.