Gutters and downpipe requirements

Hoping someone can help.

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C U S T O M. C O R A L. B R O N T E. 43
http://forum.homeone.com.au/viewtopic.php?t=79581

Hey mrsjm. Im not a plumber but I would try putting an end cap on the pipe, they are a couple of bucks from bunnings. It might be that the water velocity is quick enough that because it is open on the end its splashing out of your gutter. They are called spreaders just fyi.

Thanks picto. Much appreciated.


C U S T O M. C O R A L. B R O N T E. 43
http://forum.homeone.com.au/viewtopic.php?t=79581

I guess you would just need to keep an eye on the gutter above the alfresco if you do this. In a massive down pour it could potentially back fill. But if it does I'd just extend the spreader so that it has more holes for drainage.

z

Hahaha yeah they definitely would be. But by the looks of your thread it might be easier to fix it yourself....

I don't have the time right now to give a full reply and there is another thread that has been waiting nearly a week for a reply that has priority but have a read of the Jan 14 2.40 am post and the ones following in the link below for starters.

viewtopic.php?f=3&t=74618&start=20

z

An upper roof area drained to a lower roof area plus any abutting walls that provide additional run off during wind driven rain must be added to a lower roof area's drainage calculations.

Is it a slotted gutter and have you stood back to see where the water is coming from?

Is the red area marked on the diagram indicating areas of overflow?

Does the gutter pool water after it rains?

I can't see an alfresco downpipe indicated on the plan but I logically assume that there is one. Is there and if so, what size is it?

z

Yes, gutters are allowed to retain up to 10mm of water for 3 days after the last rainfall and be deemed compliant despite eaves gutters needing to slope. Apart from slope assisted drainage, damage comes by way of negatively charged accumulated sediments and decaying organic matter interacting with metals which are positively charged.

It would be a massive end cap leak to discharge the amount of water as described and it is remarkable if they were not able to fix this minor defect.

If I was on site, I would first check the gutter slope and use a hose to run some water off the roof for visuals as there is a need to quickly drain the water from the spreader to the diagonally opposite downpipe. To achieve this, a good slope is required. A concentrated flow of water into a slotted gutter with the downpipe seven meters away and a corner in between is poor design.

A downpipe was most probably not installed where the spreader discharges due to aesthetics but this can be worked around by hiding the downpipe.

I was wondering what the downpipe size is, is it the same as the others? Amongst the many weird things that I have seen has been small downpipes fitted to small roof areas despite a larger roof area draining to that roof.

I can't judge what area of upper roof drains to the spreader because I need to know where the gutter's high points are. The high points determine the roof area that slopes either side of the high point and the low point is where the downpipe is fitted. In any case, compliance does not guarantee good design.

Builders not fitting temporary downpipes once the roof is on and also failing to slope the land away from the slab is potentially very damaging if you are on highly reactive soil.

First few things I said to my Draftsman /architect was, want a really good drainage system and extra downpipes put in, 3_4 more than required, have seen way too many water problems due to inadequate downpipe numbers, often causes thousands and thousands of damage internally.

"For a tiled roof, the lower section shall be sarked a minimum width of 1800 mm, either
side from the point of discharge, and extended down to the eaves gutter" refers to AS3500.2 - 2018. clause 3.4.5

What is the meaning of the above requirement?

It comes under AS/NZS 3500.3 Stormwater Drainage, not AS/NZS 3500.2

Do you know what sarking is?

If there is a downpipe discharging water through a spreader from a higher roof area onto a lower tiled roof area, the lower section must be sarked a minimum of 1800mm either side of the point of discharge ( which is the spreader) and extend down to the eaves gutter in accordance with AS 2050. The sarking obviously has to extend to the gutter so that it legally discharges to an appropriate drain outside the roof space.

Hi, sorry to bring up an old thread. Do your gutters still retain water? We noticed this one our gutters on the garage, similar set up to yours. Scares me what is going on upstairs which we can't see. Wanted to see if you've had any problem with this since. We are almost a year in and still chasing Coral.

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