How to clear blocked cast iron downpipe - can I drill an access hole in the bottom and stick a drain rod up?

[michael123123]

The main downpipe on the front elevation of my house seems to be at least partially blocked - we often get a drip overflowing from the gutter and we can see that the gutter is full to the brim with water when peering out of the roof velux window.

I don't have a ladder tall enough to get to it from above, and the pipe goes directly into some concrete at ground level. Therefore, I was wondering about the feasibility of drilling an access hole at the bottom large enough to stick a drain rod in and give everything a good poke. I would then install some sort of blanking plate over the access hole to make it good.

Is that reasonable?

 

[freddiemercurystwin]

I think I'd be more inclined to cut it completely and afterwards rejoining it with a coupler, possibly two, so that you can cut a section out, temporarily. That said, I think if you have a house and expect to do some basic repairs a suitable ladder is pretty essential IMO.

That said, you can get access pipes eg https://www.wolseley.co.uk/product/center-68mm-access-pipe/

Or you could bodge something together, cut a hole, clear the blockage, fit a patch over the hole and seal with some sealant which could be riveted or maybe just bonded to the existing hole.

All assuming that you can actually clear the blockage and its not beneath wherever you make your hole.

 

[DiyNutJob]

I like poking ideas. I suggested it in other threads in the past and got banned.

You need a grinder to make an opening. After, hose clamp on a piece of flexible upvc and seal with hybrid polymer. But, don't just poke. Make sure you block falling of the debris to make sure it doesn't cause blockage further down. Cut the access high enough to make rodding easier. Be careful with electricity as your grinder might get flooded by water unexpectedly. This is a rare instance I would want to use battery powered.

 

[noseall]

The main downpipe on the front elevation of my house seems to be at least partially blocked - we often get a drip overflowing from the gutter and we can see that the gutter is full to the brim with water when peering out of the roof velux window.

I don't have a ladder tall enough to get to it from above, and the pipe goes directly into some concrete at ground level. Therefore, I was wondering about the feasibility of drilling an access hole at the bottom large enough to stick a drain rod in and give everything a good poke. I would then install some sort of blanking plate over the access hole to make it good.

Is that reasonable?

How do you know its the gutter DP and not the drain pipe, that's blocked?
It's fairly common for older soakaway pipes to fully silt up, especially those whose DP's run direct, rather than into a gulley.

 

[Harry Bloomfield]

I don't have a ladder tall enough to get to it from above, and the pipe goes directly into some concrete at ground level. Therefore, I was wondering about the feasibility of drilling an access hole at the bottom large enough to stick a drain rod in and give everything a good poke. I would then install some sort of blanking plate over the access hole to make it good.

I would suggest checking where it goes in the ground first, is there a manhole you could check first for blockages?

 

[DiyNutJob]

The blanking plate could be made from a plastic pipe/duct. It will already have the curve you need.

 

[foxhole]

Check gutter first , Down pipe probably clear .

 

[DiyNutJob]

You can locate the pipe blockage using this solution: https://www.diynot.com/diy/threads/swan-neck-restriction.593396/page-2

 

[michael123123]

Thanks for the replies, some good thoughts. I've attached some pictures for reference. The picture of the lamp post (pic 3) is what I had visualised in terms of an access hole that I alluded to in the original post, although I need to think about the advantage of cutting a whole section out and replacing with couplers. As well as thinking about whether the whole thing might be silted up and thus all of this is futile.

We get a lot of moss on the roof and in the gutter. You can see the neighbour has plants growing out of his (pic 2), whilst ours is clear along to the drainpipe (well, relatively, it could do with another clear out which we do from the loft room using a long pole).

And pic 1 is the downpipe going into a concrete base. No manhole nearby to look in.

 

[DiyNutJob]

If you cut off a section, is there risk of the pipe falling on your head? They are heavy.

 

[freddiemercurystwin]

Is it cast iron? It looks like it's been embedded in the render too so that means cutting it is out without screwing up the wall and making a hole is easier said than done. Time for a ladder I'd say. Or get a gutter clearing bloke in to have a look, a lot of window cleaners also do gutters, they'd probably have a look if you get them to do your windows.

 

[Harry Bloomfield]

That dogleg, from the gutter, back to the wall - it looks a prime location for blocking by moss, and would be my first check. You might be able to tap the fall pipe at the ground, gently with a hammer - to detect whether it is full or empty of water/debris.

 

[DiyNutJob]

The first step is to put camera on stick and see from above. Do same during heavy rain. Beware lithium battery will ignite and explode from water.

 

[noseall]

The first step is to put camera on stick and see from above. Do same during heavy rain. Beware lithium battery will ignite and explode from water.

The OP has already observed the gutter during heavy rain (via Velux wondow) and commented that its overwhelmed.
That tells us it's blocked somewhere between the running outlet and the River Trent.

 

[DiyNutJob]

The OP has already observed the gutter during heavy rain (via Velux wondow) and commented that its overwhelmed.
That tells us it's blocked somewhere between the running outlet and the River Trent.

With a garden growing up there, I am not surprised it's overwhelmed. Therefore a closer diagnosis is necessary. Maybe there is no blockage at all. The sky garden could be restricting flow.