How to replace metal downpipes with PVC?

Hello, I want to replace my old metal downpipes with new PVC ones.

I have many questions, so I'll just blurt them out.

1. What are the pros/cons of PVC vs metal?

2. To me, it makes sense to replace my existing downpipes with square PVC. But what about round? Is there a special reason to use round? Is it better? Flow better? Is it worth the extra effort?

3. @EricL I've seen you comment on these sorts of projects, if you are able to, I'd really appreciate your input here.

4. With PVC, I assume the 'main' part of the downpipe should just be one piece? As you can see in the photos, many of my old metal ones are multiple pieces (don't know why).

5. What is the best way to recreate the above connection type using PVC?

6. What is the best way to recreate this 'angled' bit using PVC connectors?

7. When installing the pops, is it possible to do this without pushing back the roof tiles? The reason I ask, is I had the tiles painted, and if I push them up, it will scratch off the paint.

All the downpipes go into 90mm round stormwater drains.

Any advice about which products to use etc is most gratefully received!

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Comments

EricL

Hello @Yabbie

Just a friendly reminder that it might be necessary to engage a licensed plumber to complete this work. If in doubt consult your local building authority before you begin.

The number one advantage of PVC is that it won't rust and is much easier to handle and cut. The drawback of course is that it does not have the strength of steel so an errant brush with the whipper snipper could lead to snapping or cracking.

A round downpipe has less chance of creating a blockage and creates better overall flow.

Due to the configuration of your metal downpipe, the PVC downpipe will need to be configured in the same manner. If a plumber were to assemble this, it's probable that they would use shallow angle bends like 15- or 35-degree bends and join two together to copy your current configuration.

In regards to the pops/dropper, I don't think it will be necessary to change it, as an adapter such as the Holman 100 x 80 x 90mm PVC Stormwater Downpipe Adaptor can be placed at the start of your assembly.

However, if you do decide to change the pops/dropper it would be easier to move the roof tiles rather than uninstalling the gutter, incorrect re-installation can lead to pooling and poor drain flow.

To hold the 90mm pipe to your wall, I propose having a look at the Kinetic 90mm DWV Pipe Saddle Clips - 4 Pack. It can be mounted to your brick wall using Ramset 8 x 50mm Universal Anchor.

If you have any other questions we can help with, please let us know.

Eric

Yabbie

https://www.workshop.bunnings.com.au/discussion/comment/37567#Comment_37567

Thanks for the reply @EricL .

Just to clarify (and based on the links you've provided), you'd suggest to use adaptors and then round down pipe for the "main" part down the wall?

I have a few that go directly into the ground like above. Into concrete. So I don't believe I can use the round pipes (without some serious adapter usage).

If I wanted to stick with square PVC, are there 15 and 35 degree angle bends? If possible, could you please provide links to the materials I'd need?

Also, without removing the existing pop, is there a trick to installing the downpipes? Because (it's a bit hard to describe), but I'd have thought you'd install them from the 'bottom up', with the pop being the last thing installed?

Yabbie

https://www.workshop.bunnings.com.au/discussion/comment/37567#Comment_37567

Overall, would you recommend using PVC these days, or metal still? When you consider cost, longevity etc.

MitchellMc

Hi @Yabbie,

Can I ask why you want to replace your metal downpipes? they are perfectly serviceable and only require a lick of paint to rejuvenate them.

You'll find our whole range of PVC downpipes, connectors and adaptors on the Bunnings website. There are no 15 or 35-degree angle bends, the closest would be 45 degrees. Your metal pops have likely been installed from the top down.

Both metal and PVC downpipes are perfectly functional, metal being the more durable option to impact, though susceptible to rusting over a long period.

If there were no downpipes, you might like to go with PVC, but if you have metal, then there's no significant reason I can see to change to PVC.

Please let me know if you have any questions.

Mitchell

Yabbie

https://www.workshop.bunnings.com.au/discussion/comment/37617#Comment_37617

Damage. Damage. Rust. Rust. Ugly. Ugly. Rust. Rust.Hi @MitchellMc,

Many of the metal downpipes leak and have dents in them. There are rivets that are rusted and things like that. If I was going to take them down to try and fix them, I thought it _might_ make more sense to replace them with PVC.

Rust/moisture at joint.Rust/moisture at joint.Adaptor damaged.

Yabbie

https://www.workshop.bunnings.com.au/discussion/comment/81048#Comment_81048

@MitchellMc as you can see in the photos in my previous comment, many of the downpipes are damaged and/or leak.

What would you suggest? Try and repair them? Replace sections? Replace the whole lot in metal? Replace the whole lot in PVC?

Many thanks.

CC: @EricL

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/105186#Comment_105186

Fair enough, @Yabbie. If their appearance is quite aged, then that would be a reason to replace them. Those joins and pop rivets are all part of having metal downpipes; they need to be cut to get the angles. The rust is likely just on the surface, so it could be cleaned up with some sandpaper. You'd then just need to paint them while in place with Dulux Weathershield.

If the dents bother you, fresh PVC downpipes would certainly be an upgrade. If you were to install new metal downpipes, they'd still need to be cut and pop-rivets placed in similar locations. It sounds like PVC would be your best choice for a nicer looking installation.

Mitchell

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