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Posted: Wed Nov 07, 2012 11:40 pm
by niallcook
First post here so please be gentle. I have an open surface water drain (called a "dry area" I think) running along the length of my house where the external ground level is higher than internal. It is of concrete/metal construction with heavy slotted grates resting atop. It discharges surface and roof water into the "normal" drains at either end and appears to do its job quite well as long as it is kept clear.
The problem is that it is ugly as sin (it's a Listed property) so I was wondering if I could just remove the heavy metal grates and fill the lot with gravel - or will this restrict the flow of water too much? If this is a possibility how would you experts go about it (gravel size, etc.).
Thanks in advance.
Posted: Thu Nov 08, 2012 5:21 am
by Dave_L
I guess you could fill it with a 40mm clean limestone without impairing the water flow too much.
How far away are the exits for the water from the downpipes as this is where most of the water flow wil come from?
Posted: Thu Nov 08, 2012 7:52 am
by niallcook
Dave_L wrote:I guess you could fill it with a 40mm clean limestone without impairing the water flow too much.
How far away are the exits for the water from the downpipes as this is where most of the water flow wil come from?
Thanks for the response. The length of the drain is around 28m, and there's a small section of lean-to roof that discharges directly into it. One downpipe is directly above the end where it gets taken away and the other is about 6m from that. The rest I presume is more to keep and surface damp or rain away from the house wall.
Any further advance most welcome.
Posted: Thu Nov 08, 2012 7:59 am
by GB_Groundworks
It will block in a year or two given the wash of drebris from the roof etc, so not advisable, you'd need to protect the outfall as well with geotexttile.
Is a new grating top an option? Pictures would help, host them online then link back here if not email them me and I'll post them up.
Posted: Thu Nov 08, 2012 9:49 am
by niallcook
GB_Groundworks wrote:It will block in a year or two given the wash of drebris from the roof etc, so not advisable, you'd need to protect the outfall as well with geotexttile.
Is a new grating top an option? Pictures would help, host them online then link back here if not email them me and I'll post them up.
A new grating top could be an option, but it is rather wide (at least 12" I would say, so not sure what is available to fit).
Picture of the grating below.
Posted: Thu Nov 08, 2012 6:25 pm
by Tony McC
That looks overly wide to be a pure drainage channel. It looks like the sort of thing that is a combined drainage and ventilation yoke. On some properties, a structural engineer will recommend ventilation to the external masonry as one compnenet of an anti-damp strategy, and in such cases, it tends to be a 200-450mmm wide channel rather than the more usual 100-150mm drainage channel.
If that is the case, then filling it with gravel will hinder the ventilation, so I'd say leave well alone.
I'd also go with Gi's suggestion: get a different grating. There are some very attractive ones available nowadays such as these
Posted: Thu Nov 08, 2012 6:37 pm
by niallcook
Tony McC wrote:That looks overly wide to be a pure drainage channel. It looks like the sort of thing that is a combined drainage and ventilation yoke. On some properties, a structural engineer will recommend ventilation to the external masonry as one compnenet of an anti-damp strategy, and in such cases, it tends to be a 200-450mmm wide channel rather than the more usual 100-150mm drainage channel.
If that is the case, then filling it with gravel will hinder the ventilation, so I'd say leave well alone.
I'd also go with Gi's suggestion: get a different grating. There are some very attractive ones available nowadays such as these
Thanks for the advice. I agree that those grates would look very good - although not sure they would be wide enough for our "yoke". But certainly gives us a starting point.