Convert cemented in down pipe to open gully

23 May 2008
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United Kingdom
I have just moved in to a house with guttering downpipes that appear to be quite solidly cemented into the ground, presumably connecting to main drainage below the surface. The downpipes are full to a height of about four feet with moss, causing leakage further up. I'll obviously have to remove and clear the pipes but would prefer them to terminate above ground with a gully (think that's the right word, or maybe 'hopper') with a grille over it to catch debris. I'm not sure how involved it would be to convert them - or if it's even possible. Can anyone advise of the steps involved please?
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I will take a punt and say it must be cast iron and not plastic then,
if so then a pipe cutter or an angle grinder
jon92 good evening.

My first move would be to excavate out at the base of the down pipes, in your Original post you do not say if the Down Pipes are Plastic or Cast Iron? or even Asbestos?

Depending on what you find, you will probably have to remove the first length of Down pipe to clear the blockage in the pipe, You may have to rotate the pipe to get it free but then there is the problem of not enough space to lift the length of pipe up out of what will probably be a buried bend so as to free off the length you need to remove. One possibility is the cut the down pipe and using a rubber coupling you can re-join the length of Down pipe once the blockage is addressed.

As for the "Hopper" best known as a "Gully" if you are going to install these, get all the bits you need before you start, that is the gully itself, loads of different types on the market, cut the Down Pipe above ground at a suitable height so you can fit a small bend to deflect the rain water into the Gully, plus a small clearance between the lip of the bend and where your new Gully will be sited, that,s all above ground.

Below ground, remove all of the vertical pipework from the bend to the cut you made and then re-cut this pipe making an allowance for the height of the gully re-fit. then re-secure the above ground pipe to stop it moving at the bend.

Next thing to consider, why did the Moss build up in the pipe in the first place? the moss is obviously present on the roof, you can fit a grating in the rain water gutter at the down pipe, or? fit copper ridging [expensive] or even string bare copper wires horizontally over the roof, the copper stops the formation of moss on roofs, it produces Copper Sulphate in contact with Acid Rain.

Sorry I should have said, the pipes are plastic. Thanks for the comprehensive help, I think you're right that digging down would be a good start to see what I'm dealing with.
If I manage the job and end up with the top of the gully at ground level, should I build something around it? I've noticed that there is usually a little concrete 'wall' around them, presumably to contain any splashes of water.
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jon92 Hi again.

OK Plastic, good because it is far, far easier to work with.

First, I would as carefully cut into the top surface, remember you will have to replace this surface, so if you can keep the cut as square and aesthetic as you can, as an aside, what is the top surface?

The area of the cut above will have to be a space large enough to complete the repair.

Excavate the earth away, leaving for the moment the pipework both above and below ground in place, if you cut the Down pipe now it will loose a lot of stability when excavating below ground.

One tip try to find a makers name on the pipework makes fitting new bits easier so use the brand name on your pipes.

If possible, excavate down to the "bend" which is the transition between the Down pipe and the sloping underground drain, with luck this "bemd" will be between and below ground, I have seen them over a meter underground.

Clear away as much as you can of the earth, to allow you to see the down pipe into the "bend"

Now you can cut the Down pipe, I would suggest that this cut, keep it as square and level as possible about to above ground, a hack-Saw will do this.

Restrain the pipe above the one you have just cut, if you do not then that pipe can fall out at you.

Remove the cut pipe and clear it.

Next remove the underground pipe and clear that.

Now for the measuring bit, get your new gully and measure from top surface to the inner stop for the pipe fitting, if you can cut the pipe square, to get the fit between pipe and new Gully, assemble the old pipe plus the Gully and see how it fits as regards ground level and the top lip of the Gully.

But? If I were to fit the Gully, I would drop the lip [top] level of the gully below the level of the top surface, why? because when you finish off the top surface you should using a fine concrete run the concrete down wards towards the top lip of the gully, it assists in getting any spilled water to run into the Gully.

One final thing. if it starts to rain whilst you are undertaking the work make provision for diverting the rain water coming down at you in the Down Pipe, you can temporary refit the cut Down Pipe, but shed the water well away from the excavation!

Ken thank you very much, I can see this isn't going to be a 10 minute job. The surface is just shingle but I think there is a layer of tarmac underneath - unfortunately I don't have evenings free to work on it but I will start on Saturday. If it ends up needing a metre of digging then I will probably throw in the towel and resign myself to periodic checks for blockages. I will get some sort of grille to put over the guttering as you suggest, at least that will alleviate it.
Thanks again for taking the time to post all the instructions.
Don't know if it is the same all over the country but Thames water say that a down pipe that goes straight into the ground generally means a soak-away. If it has a break, then it goes into a drain.

I get money off my water bill because the house was built with down pipes straight into concrete
Tried to dig down today, there is tarmac under the shingle so I didn't get very far. The downpipe is stuck fast, I tried to twist it out as best I could but not a hint of movement. I might try to break it out of the tarmac when I have a bit more time, on the other hand the whole guttering system needs replacing so maybe I'll just leave it to a professional.
Thanks for the all the help.

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