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Guttering Droppers

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  1. #1
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    Default Guttering Droppers

    Hi all,
    I've just had a nice man replace all of the guttering on our house. As it two story on a slope (nearly 6 m) I decided against doing it myself.

    Anyhoo, I had him install 90mm droppers but now I find that when adding the downpipes, 90mm downpipe is not even a loose fit, its down right sloppy!

    Obviously I've missed something. Do I just bang it on and screw it to keep it up there! Or is there a fitting I have missed.

    Ralph

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    1K Club Member Godzilla73's Avatar
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    G'day, are you using metal or pvc? Either way one end is flared to take another section. On pvc it's easy to see, metal on the other hand is less so. Only other thing it could be is they used 75mm outlets. Most outlets have a bit of a rib for a snug fit on all ones i've done.

  3. #3
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    Hi, thanks,
    Metal droppers. I suspect they've used 75mm (at least on the corner I am adding the PVC pipe to).

    Ralph

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    1K Club Member Godzilla73's Avatar
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    Hmmm, bugger. Hopefully you can find an adaptor of some sort.

  5. #5
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    I think you'll find they've used 75mm. Having some, but limited. experience in storm water works, in 'standard household' guttering profiles even 75mm outlets (or 'pops' as I've called them - don't know where I got that term from ) are a tight fit especially considering the wider flange that goes on the inside of the gutter to help the seal and to hold them there. I used 75mm downpipes and converted to 90mm at ground level.

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    Quote Originally Posted by r3nov8or View Post
    I think you'll find they've used 75mm. Having some, but limited. experience in storm water works, in 'standard household' guttering profiles even 75mm outlets (or 'pops' as I've called them - don't know where I got that term from ) are a tight fit especially considering the wider flange that goes on the inside of the gutter to help the seal and to hold them there. I used 75mm downpipes and converted to 90mm at ground level.
    Yep,
    That's what I reckon. 75-80 mm pipe here I go!

    Ralph

  7. #7
    1K Club Member Godzilla73's Avatar
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    Yeah 90mm can be a pain to fit into std quad type gutter, takes some bending and stuffing about. Be a bit strange if they've mixed 90 and 75 though.

  8. #8
    4K Club Member ringtail's Avatar
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    All the standard metal droppers are a much smaller o/d than the 90 mm pvc i/d. Just stick a short roofing type screw through the lot or use a decent rivet.

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    I see you are from Brisbane and I hear that storm water plumbing is Rafferty rules up there as the Brisbane City Council considers it an unregulated activity. Nevertheless, it should still come under the building code (maybe?).

    First step is to contact the nice man who installed your guttering. After that, it is up to you!

    You need to be aware that the pop size (or whatever it is called up there) is what determines the downpipe's flow rate. Water enters the pop as 'weir flow' and the cross section area is critical. A 90 mm metal pipe has a cross sectional area of 6,364 sq mm whereas a 75 mm pipe is only 4,420 sq mm. The pops will be smaller again! If the roof area harvested to each downpipe requires 90 mm downpipes (i.e. pops), the gutters will have severe overflowing problems if the pops are only 75 mm, no matter how big the downpipes are.

    If there is anyway you can measure the size before you contact him, it would pay to do so.

  10. #10
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    Quote Originally Posted by ringtail View Post
    All the standard metal droppers are a much smaller o/d than the 90 mm pvc i/d. Just stick a short roofing type screw through the lot or use a decent rivet.
    Yup, it's true.
    Luckily, the nice man is back again tomorrow to pick up his planks and trestles so I'll ask and confirm for sure. Other than that, a sturdy screw it is!

    Ralph

  11. #11
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    You will find that the quad gutter here in Brisbane is bigger than the quad in Vic.
    Standard Down Pipe drops up here are 90 mm and the 100x75. since early retirement a few years ago they have invented a down pipe drop that fits both square and round yes strange indeed. If he has used one of these it may be the reason it feels so sloppy.
    It would be pretty unusual that he put in a 75 mm dropper.
    In 10 years of putting up gutter here in Bris I would have installed 10, 75 mm droppers compared to the hundreds of 90mm and 100x75.

    Down pipes won't hang there on their own just wack a screw in it.

    Like you said , when he comes back just ask. And also don't forget that the expanded end of the pvc will make it seem even looser.

  12. #12
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    Thanks Fishnmick,
    I didn't think that 75mm would be the case either! We have repeatedly discussed 90mm, as I have gone from old 4"x3" and decided against 100x75 as I have a few bends and turns to achieve at a few of the corners (to get to the storm water pit covers). Maybe you are right with the square and round gismo! I'll keep you posted.

    Ralph

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    Quote Originally Posted by Danny View Post
    I see you are from Brisbane and I hear that storm water plumbing is Rafferty rules up there as the Brisbane City Council considers it an unregulated activity. Nevertheless, it should still come under the building code (maybe?).

    First step is to contact the nice man who installed your guttering. After that, it is up to you!

    You need to be aware that the pop size (or whatever it is called up there) is what determines the downpipe's flow rate. Water enters the pop as 'weir flow' and the cross section area is critical. A 90 mm metal pipe has a cross sectional area of 6,364 sq mm whereas a 75 mm pipe is only 4,420 sq mm. The pops will be smaller again! If the roof area harvested to each downpipe requires 90 mm downpipes (i.e. pops), the gutters will have severe overflowing problems if the pops are only 75 mm, no matter how big the downpipes are.

    If there is anyway you can measure the size before you contact him, it would pay to do so.

    Hay Danny, Do you do house calls to Inverell? My gutters always overflow in a half descent gully raker. I'd love to be able to cure that.

  14. #14
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    Quote Originally Posted by fishnmick View Post
    Standard Down Pipe drops up here are 90 mm and the 100x75. since early retirement a few years ago they have invented a down pipe drop that fits both square and round yes strange indeed. If he has used one of these it may be the reason it feels so sloppy.
    Hi Fishmick,

    Ok, this has really got me! The 100x75 is rectangular, how can the same drop also fit a 90 mm round? Are you able to link a website with a photo or similar? Is it rigid or flexible?

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    Fishnmick,
    A side discussion, what's your thoughts on connecting to the stormwater?
    Currently I have a number of 150mm bolted trap screw covers. My options are to remove them and use 100 to 90 reducers and connect the downpipe or (my pref) is to replace the bolted trap screw covers with grates and stop the downpipe short.
    I don't care either way, just reckon it'll look flasher with grates.

    Ralph

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    Quote Originally Posted by Danny View Post
    You need to be aware that the pop size (or whatever it is called up there) is what determines the downpipe's flow rate. Water enters the pop as 'weir flow' and the cross section area is critical. A 90 mm metal pipe has a cross sectional area of 6,364 sq mm whereas a 75 mm pipe is only 4,420 sq mm. The pops will be smaller again! If the roof area harvested to each downpipe requires 90 mm downpipes (i.e. pops), the gutters will have severe overflowing problems if the pops are only 75 mm, no matter how big the downpipes are.
    Thanks,
    I haven't bothered to calculate anything! I am working on the more is better principal. The house was built in the 70's in a non mains water area.The gutter was falled for all the roof to exit from 3 drops (pops) on one side of the house (tanks). In that time (including the great Gap storm and recent rains) it has seemed to handle it or overfow out not in. I am getting the gentlemen to install a drop on every corner and fall accordingly. I reckon I'll be right with 75's if they are indeed 75's.

    Cheers
    Ralph

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    Quote Originally Posted by mark53 View Post
    Hay Danny, Do you do house calls to Inverell? My gutters always overflow in a half descent gully raker. I'd love to be able to cure that.
    Afraid not. I actually work in new product research and development but your prayers will soon be answered.

  18. #18
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    Ralph , I really can't comment about storm water connection as my licence was only for roof, gutter and wall cladding and it stopped at the ground.

    But ,With my place and the very old stormwater pipes couldn't handle a down pour and used to flood the gutters and down pipes. I ended up putting a grate on the ground stormwater connection and have an open down pipe spilling on to that.Now when the stormwater backs up it just spills on to the grass. Many houses in Bris still have down pipes spilling onto the grass.

    The down pipes drops that suit 90mm round and 100 x75 are available up here at Stratco. They call them a "universal" drop.

  19. #19
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    All cool,
    I asked the nice man, he showed me the droppers and they are indeed a 90mm dropper. I just used a short gal tec screw and now everything is fine and dandy!
    Thanks for all the help and advice!
    Ralph

  20. #20
    4K Club Member ringtail's Avatar
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    Thats all you need man. Its only a downpipe. If you want to get really anal you can put a reducer into the end of the 90 pipe ( non flared) to get a tighter fit, but I'll tell you, no plumber will do it. Screw or rivet, thats it. As long as its up against the bottom of the quad you cant tell anyway. Biggest mistake people make - plumbers included ,is installing the dropper from the inside of the quad and gooing it up, forcing the water to fill up and over the goo mound. This also leaves water sitting in the gutter.

  21. #21
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    Quote Originally Posted by ringtail View Post
    Biggest mistake people make - plumbers included ,is installing the dropper from the inside of the quad and gooing it up, forcing the water to fill up and over the goo mound. This also leaves water sitting in the gutter.
    I am so smart! I asked this question of the nice man, and he said (I watched from the ground) that he only uses pop rivets to hols the droppers in. There are two or three on each dropper. Chuffed!

    Ralph

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