Advice on drainage groove in concrete patio.

[Roy22]

I have a long standing problem with rainwater seeping under the door of a lean-to. The old concrete patio slopes down towards the lean-to and nearby sunken drain for the whole house, but the slope also lets some water seep under the lean-to's door.

My question is about cutting some kind of groove directing water to the drain just to the right of the affected area. It's not a huge problem, perhaps a few litres of water gets in with heavy rain, enough to wet a doormat and slowly rot door posts. So I'm not looking for some major drainage installation, just a groove wide or deep enough to divert this small flow. It'll need to be as wide as the door threshold, at one side angled to meet the wall so it doesn't creep behind the groove, at the other side leading away to the drain. It will be quite visible across the threshold, another reason to be as discrete as possible.

So would cutting a half inch wide channel, maybe an inch deep, be sufficient? Online research suggests using an angle grinder with diamond blade to create the two parallel lines, then a chisel to clear between them, would work. Others say angle the two cuts to form a 'V' groove, so easier to clear.

Any advice or opinions greatly received on how wide or deep to make this groove etc.

[seanandruby]

Sounds like your wanting the nod to do a bodge job. You need a threshold drain proper, maybe a linear drain. Cutting little grooves eventually silt up adding to the problem. some photo's would be handy. Rotting threshold is a major problem.
look here for work arounds

[Roy22]

I'm not looking for a bodge job. But we are only talking about a litre of two of water seeping under a door after heavy rain. A linear drain would be a sledge hammer to crack a nut.

I've lived with the problem for quite some time, replacing sections of rotted lower door post periodically. A working drain groove ought to stop this, clearing the silt out periodically would be a small price to pay.

The workarounds linked to are way too elaborate. I have followed this advice in the past, creating a gravel filled French drain where concrete breached DPC, so I'm no stranger to hard work or robust solutions. But that isn't appropriate here, especially in an old concrete/lean-to area ripe for complete redevelopment by a future owner.

If anyone has some advice on such a moderate solution, please fire away.

[seanandruby]

Is the hardstanding breaching the DPC all along the wall then ???

[seanandruby]

It's not a huge problem, perhaps a few litres of water gets in with heavy rain, enough to wet a doormat and slowly rot door posts.

Sounds like "a huge problem to me." It's "rotting door posts."

[Roy22]

There's no breach of DPC; I was referring to a past job elsewhere, installing a gravel filled French drain. That was appropriate as the DPC had been compromised by too high a concrete level. This problem is rather trivial in comparison.

The end grain of a wooden door post will of course soak up water that reaches it, so even an occasional/light seepage will over years encourage wet rot. That's the nature of wood in exposed places, rather than a major problem.

As installing a Linear Drain would mean cutting a relatively huge trench, with god-knows how many litres capacity, that would be real overkill, especially as I say it's an area past its sell-by date. I was looking for something fairly easy to keep the problem at bay until then.

But if you find this kind of solution too offensive to your standards, as perhaps a professional installer, feel free to leave this thread to those with lower expectations/standards.

[seanandruby]

Listen Brummie, i have given you my thoughts so don't have a go at me. There isn't anyone on this site with "lower expectations/standards," that's why it's called paving expert. Without photo's we can only imagine the job, that is why I asked for some. You have made up your mind about cutting a groove out but you just want us to give you the green light to do it, so why don't you take the advice given and cut the groove ? Cutting a groove so that the water ends up flowing against the brickwork isn't a good idea, forming a channel to the existing drain is better.

[Roy22]

Sorry to disappoint, but I'm not from Birmingham, I just happen to live here right now. But the implied slight is noted.

I wasn't looking for a 'green light' from anyone, just a little practical advice on what has worked for others. It's a solution widely used elsewhere, not something odd I dreamt up.

I think it's abundantly clear I'm not going to carry out a major fix for a minor problem on an old area. Once that point's reached, it's probably wise for the Professionals to step aside having said their piece.

Carrying on and on beyond that point can look just a little like trolling.

[seanandruby]

I really can't see why you posted in the first place, it's gone full circle back to you cutting a groove ??? Good luck to you.

[GB_Groundworks]

your doing a bodge, hence Sean's annoyance, it might work once or twice but any serious rain you'll have water bypass it defeating the point of doing it? fit a cheap ups door and frame? cutting two groves and trying to knock out a small channel is similar in time and work to just cut out a channel and install a linear drain, i did one in front of a garage the other day only took 2 hours to cut out and install 3.5m channel drain.

when we are installing new stable blocks we use a grooving tool to install grooves in the concrete as we trowel it to allow for more efficient removal of urine once rubber mats and straw are down, we do these at 150mm centres running with the fall of the slab to the drain point or out the door



Edited By GB_Groundworks on 1465766694