How to fix dripping PVC guttering join

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timmmay

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#294051 2-Mar-2022 11:00

I have a leaky join between guttering and the downpipe bit. In the photo it's the bit that's all black / green with the obvious signs of sealer that used to be there.

It's leaked on and off for years. I generally put on some clear silicone inside and outside and it lasts a couple of years, but I'm wondering if there's a more permanent way. I know there is a PVC cement / solvent, but I guess I might have to take things apart for that to work. I don't really want to take this down as typically something will go wrong that will require multiple trips to the hardware store to get parts and take half a day.

Any suggestions how to fix this ideally without taking the guttering down?

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#2877637 2-Mar-2022 11:31

You really want to clean the old gunk off the surfaces first which will be difficult with it in place, but just prying it apart and jamming a bunch of this in should sort it.

If you don't have a gun, you can buy it like this, but it's like triple the price.

timmmay

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#2877639 2-Mar-2022 11:33

Yeah I do clean the gunk off each time I do anything, it builds up as it leaks, it's due a clean. I'll have a look for that stuff at the hardware store thanks.

nickb800

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#2877642 2-Mar-2022 11:39

How long is the spouting run, and are there any expansion joints along the way? PVC expands a lot in response to changes in heat, so generally need expansion joints to allow for that. You could retrofit an expansion coupler somewhere in the middle of the run. My first guess is that you're doing a fine job with sealant, but thermal expansion is ripping it apart over time.

RunningMan

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#2877643 2-Mar-2022 11:45

That will often be a sliding expansion joint so sealant will interfere with it. Perhaps try sloping the downpipe connector section to the left so water doesn't migrate back under the join. Alternatively, lengthen the guttering so it protrudes into the downpipe connector section more.

timmmay

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#2877654 2-Mar-2022 11:56

nickb800:

How long is the spouting run, and are there any expansion joints along the way? PVC expands a lot in response to changes in heat, so generally need expansion joints to allow for that. You could retrofit an expansion coupler somewhere in the middle of the run. My first guess is that you're doing a fine job with sealant, but thermal expansion is ripping it apart over time.

It's a 6m run of guttering with no apparent expansion joint anywhere. Looking in there it looks like there might be a few mm of expansion possible just with the guttering sliding against the outlet, but that's not sealed in any way. There's about 3-4cm of fall across the 6m gutter length.

timmmay

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#2877656 2-Mar-2022 11:58

RunningMan:

That will often be a sliding expansion joint so sealant will interfere with it. Perhaps try sloping the downpipe connector section to the left so water doesn't migrate back under the join. Alternatively, lengthen the guttering so it protrudes into the downpipe connector section more.

If the guttering went further that might work. Sounds like I might need to get a builder / plumber to do something if it needs to be replaced or something. Or maybe I just clean it and bung some more sealent in and hope it lasts another couple of years before I have to do it again.

wratterus

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#2877660 2-Mar-2022 12:03

Looks like whatever sealant was used last time is quite rigid? That roof and gutter stuff is fairly flexible. Would expect you to get at least a few years before it craps out again.

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#2877664 2-Mar-2022 12:09

Normally if the downpipe isn't blocked you wouldn't have any water reaching that sliding joint as it would drop down the header. It usually doesn't need sealing. I think the gutters are cut short so water is able to go backwards through the joint even when there's just a dribble.

You could try getting some sealer in the joint rather than just at the end. The gutter should unclip and lift far enough.

elpenguino

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#2877665 2-Mar-2022 12:10

timmmay:

nickb800:

How long is the spouting run, and are there any expansion joints along the way? PVC expands a lot in response to changes in heat, so generally need expansion joints to allow for that. You could retrofit an expansion coupler somewhere in the middle of the run. My first guess is that you're doing a fine job with sealant, but thermal expansion is ripping it apart over time.

It's a 6m run of guttering with no apparent expansion joint anywhere. Looking in there it looks like there might be a few mm of expansion possible just with the guttering sliding against the outlet, but that's not sealed in any way. There's about 3-4cm of fall across the 6m gutter length.

Look, where the spouting can extend to is marked for you :-)

I suspect your spouting doesn't have enough overlap into the deeper part of the outlet unit.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

timmmay

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#2877684 2-Mar-2022 12:16

Ah, so it has the expansion join but the guy who installed it cut the guttering too short. Great. I understand that part now.

I guess I'll unclip things and try to get some flexible sealer into the joint itself. That might be good enough to last a while.

Thanks all :)

wellygary

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#2877699 2-Mar-2022 12:45

timmmay:

Ah, so it has the expansion join but the guy who installed it cut the guttering too short. Great. I understand that part now.

I guess I'll unclip things and try to get some flexible sealer into the joint itself. That might be good enough to last a while.

Thanks all :)

To be honest the best solution is probably to extend the guttering so its fully over the edge of the downpipe well....

Slice the run just short of the downpipe module, add a joiner and a slightly longer run so it goes well into the downpipe section (but short of the markers)...

I know its a PITA but its probably the only true long term solution..

timmmay

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#2877703 2-Mar-2022 12:55

wellygary:

To be honest the best solution is probably to extend the guttering so its fully over the edge of the downpipe well....

Slice the run just short of the downpipe module, add a joiner and a slightly longer run so it goes well into the downpipe section (but short of the markers)...

I know its a PITA but its probably the only true long term solution..

Agreed, thanks. Next time I have a builder here they can do it as it's a small extra job, as I'm probably going to botch it if I try it. I think I'll do the silicone as a temp fix until I next have a builder / plumber in.

nickb800

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#2877719 2-Mar-2022 13:40

I wouldn't bother taking it apart, I don't think having sealant 'in' the join as opposed to on the end of the join will make much difference. The sealant will end up being super thin (like less than 1mm) and quite wide (like 10mm) which is not an optimal ratio for silicone sealant to act flexibly. In your photos you can see movement of almost 10mm - that's beyond the flexibility of any normal sealant, including roof/gutter stuff.

Honestly, just keep doing what you've been doing to tide yourself over until you get a handyman in. If you end up feeling adventurous, I think the slightly easier (but slightly less aesthetically pleasing) option is to install an expansion coupling next to the outlet coupling. Grab this, cut the spouting say 150mm off the end of the outlet coupling, and glue it in. Then re-glue the spouting into the outlet.

richms

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#2877770 2-Mar-2022 14:12

I would undo the bracket for the trap and move it right so that the spouting reaches the line that its supposed to reach. That will mean it has a bit on the left that misses anything but thats better than a massive leak.

Richard rich.ms

RunningMan

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#2877780 2-Mar-2022 14:30

timmmay:

It's a 6m run of guttering with no apparent expansion joint anywhere.

The bit you have photographed is the expansion joint, but the gutter just doesn't come far enough in to it. Sealant will just interfere with the expansion and shouldn't be needed.

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