Gutters and downpipes

[Graeme]

Simple job? Don't be silly. Long story short, blocked downpipe [1], but now need new downpipe. The bottom half is original cast iron, and a short test length of modern plastic 68mm pipe is a bit loose, say 2 or

3mm. Will that matter? Fall is vertical, and I would prefer to retain the bottom six feet, which is cast, and just replace the length from there up to the gutter. [1] Victorian house, mostly still original cast gutters and other fittings. Discovered today that one downpipe is original cast iron for the final six feet, but the eight feet or so above is something I have never seen before. There is a seam at the rear, and the material is metal, possibly galvanised, zinc or similar. Quite thin - trying to remove it, I put my thumb through it.

[nothanks]

As long as the top piece goes inside the bottom piece a slight gap can't matter. If everything else is CI then why not replace this top section with CI? When I replaced some CI I found that the gaps were quite large so I locked-up the joint by tapping-in a strip of lead sheet, then topped-off (flaunched?) the joint with a little mortar to give a run-off.

[tabbypurr]

pack the joint with linseed putty.

NT

[Graeme]

OK, thanks. Ideally the replacement will be CI, but as the only spare length to hand (i.e. in the shed) is plastic, that will do for now.

[Graeme]

Sounds good. I was planning to use whatever silicone sealant I can find in the shed, but am sure I have putty too.

[Brian Gaff]

I'm sure it had a little plaque on it saying fitted by bodgit and run gutter and plumbing experts. The worst ones for such things are the square downpipes.

One of the issues is often the different expansion rates of the materials used, particularly if plastic and cast iron are used. Unless in a conservation area, I think I'd go with a good quality plastic for all of it. Much less hassle in the long run even if it does tick on hot days! Brian

[Harry Bloomfield]

Brian Gaff explained :

The worst for what such things Brian?

All of my gutters and fallpipes are square, I have not noticed any problems particularly since I fitted them around 6 years ago.

[newshound]

Seamed pipe is a post-victorian pre-plastic replacement for cast iron. Galvanized IIRC. Also found in industrial / farming properties, cheaper and much lighter than CI so easier to install in longer lengths.

[Graeme]

In message [e-mail]>, newshound [e-mail]> writes

Thanks for that. Not something I have seen before, and what you say certainly fits. Now repaired, and waiting for overnight rain to ensure it all works!