# Forum Home Renovation Roofing  Gutters overflowing backwards onto my eaves and then down bedroom sliding door window

## DaleBlack

Hi 
In high rainfall, a couple of my rooms with sliding doors end up having water streaming down the outside of the glass and some of the eaves have a black discolouring (mold?) 
I assume the gutters are backing up in these areas with water running along the eaves then to the windows. I have been told that because the eaves run right onto the top of the frame, the lintel (metal support spanning gaps in brickwork?) would be sitting on top of the sliding door frame and the water wld follow this path. See 2nd image. 
I intend to put either some more downpipes or multiple simple outlet pipes (not sure the name)that you cut into your gutter and it just disperses the water out on angle onto the ground (obviously this means its not going into a soak well) 
If this extra capacity does not help I was wondering what people thought of diagram 2 in this link, where it says    

> Alternatively flashing can be installed under the roof covering and down  over the fascia provided the front bead of the gutter is below the  height nominated in Table G1 as depicted in Diagram (b);

  I assume i would take the tile off from the first row and fasten the flashing from that batten down into the fascia side inner surface of the gutter. 
Questions -  
1- where could I buy this flashing, what is the material type and exactly how should i fasten it?  
2-  the 1st image shows how tight the tiles to the gutter are as well as the pergola sheets coming down, in fact Ive never seen such a tight gutter - should i consider putting wider gutters in? (a guy who inspected said the pergola should have its own gutters actually?) 
3 - any suggestions in general?

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## PeteV

i'm no plumber, but to me i reckon that gutter is way too small! you need to put a bigger box gutter in with an overflow setup.

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## Danny

Need a bit more info than what has been supplied. 
Size & type of gutter.
Position & size of downpipes & the distance between the downpipes.
Your location. Your profile states Australia! Info needed for ARI.
Both roof areas (plan area).
The area (position) that overflows. 
Have you done a flow test to find the gutter's high point?  *EDIT:*  Are your gutters otherwise in good condition?

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## The Roofer

Dale,
As Danny says - more info - but if the pergola has been added to flow back into the house gutter, it means that the capacity of the house gutter has been over loaded - the gutter will also have a lower back - so the excess water flows back through the eaves. The flashing you speak of will not work if outlets are inadequate and gutter size too small. Highly recommend a roofing plummber to inspect - I would say you need a full length box gutter complete with rainhead & overflow outlet.
You'll probably need something like this:

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## The Roofer

Dale, 
Also forgot to mention any sheetmetal shops, rolformers (Lysaght, Metroll, Stratco, Stramit, Fielders etc) can do the box guuters (and flashings).

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## DaleBlack



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## DaleBlack

Hi thanks for the replies, 
With that picture of the box gutter, what do the red lines mean? that I should cut the tiles and pergola sheeting down? 
Other details (including image above) 
Location Perth: not too much rain but high rain in bursts and coastal sand no clay. 
Roof Pitch 18 degrees according to a plan comment. 
See overhead plan diagram with the red crosses illustrating current downpipes (not the rear stretch only has 1 and long side only 2, but the pergola area which has 2 of the 3 windows suffering water flowing down them actually has 3 downpipes. 
I will attempt to find some broad angle shots of the roof itself, as Iam not currently living there to take them at will. 
Danny: gutters at this place are only average, when i felt under the tile (didnt remove any yet) onto the inner surface of the gutter (fascia side) there were some rusty areas - I assume if its rusty gutters then just adding downpipes to increase capacity will not fix it alone as some water is going to penetrate backwards through potential rust anyway?

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## DaleBlack

Some more pictures I still had on the camera showing the roof condition in general and the area under the pergola

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## The Roofer

Hi Dale, 
Yes, pics help a little - not much room for a bigger section box gutter - but maybe your only choice if you don't want to replace the pergola!
I'd go for a gutter section that sits on the support beams and joins with the house fascia as per: Problem with this is joining existing gutter (have to use a rainhead at downpipes each end)
This would run three sides of the pergola - not an easy job - definately roof plumber - plus they may be able to offer a larger standard rollformed gutter that will fit and save all the hassle. I think WA does a large OG or Quad - may work - plus I'd increase your downpipe sizes on the three sides to at least 90mm round as the ones in photo look like 100x50? If you fit a larger standard gutter - make sure it has overflow slots or holes in the front to prevent backflow into the fascia side.
Good luck!

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## The Roofer

To Danny, 
Would your new device work in this instance?

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## DaleBlack

Hi thanks for the reply. 
I dont particularly love the pergola, it was there when we bought the place, that said if I took it down I would only be thinking later of putting a new one up, so not sure if it would be worth taking down unless a roof plumber decrees its just too hard with it there. 
Your picture shows in those red lines, effectively a gutter with 'wings' almost like a gutter combined with tile flashing as per the other attached picture. You will note I also attached a image I found of the OG and quad profile and they do not have the wings your diagram has?? is this a custom drawing of yours that would need a custom build? 
Also, I notice the OG and Quad profiles both have a higher front side than the rear leaving the water no where to go if gutter capacity is overwhelmed but backwards. This is common today isnt it? as people cosmetically prefer it.

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## The Roofer

Dale, 
Yes, the removal of the pergola may be the best solution - check with a plumber first on cost etc. You may have to replace the gutters anyway if they are rusted + a properly designed pergola will (should) take into account the water flows and quanties. Gutter with higher fronts should have the overflow slots (total) equal to or more in cross sectional area than the downpipe cross sectional areas.  The drawing (sketch) is just a guide and would need on site measuring and then folded in a sheetmetal shop - can be done easily - but needs to allow for fall etc so may need to be tapered if fascia has no fall to outlet positions (as many are). 
Once again - someone should inspect this for you before you decide to do anything.

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## Danny

Hi DaleBlack & The Roofer,   

> Would your new device work in this instance?

  Possibly. We have finished die trials and have done metal safe  adjustments on our outlet die and a second (nut) die is finished except  for sparking the thread. Once we nitride, we will be in production. I  could supply die trial components (F.O.C.) if I thought they were the  answer. I would prefer someone like yourself to have privy so as to be  able to provide unbiased advice.  
I am thrown by the downpipes coming through the eaves well back from the  guttering and I cannot see how it is an optical illusion. How do the  downpipes connect to the guttering?  
The downpipe locations are 'interesting'. With the Perth 1:20 ARI, the  100 X 50 mm downpipes would have a (guesstimated) maximum compliant roof  harvest area of about 44 sq m. The gutter overflow on the wall on the  RHS of the diagram could be explained by the largest area of roof been  between the two downpipes and 4 corners separating both downpipes. I  would also assume that the high point is the top RH corner. The next  downpipe however is very close to this corner. Interesting!
Nevertheless, having downpipes positioned away from the most  concentrated harvest area is common as are gutters that overflow from  high point areas between two downpipes. 
To remedy this area, you need either bigger gutters and downpipes or my  new 'device'. To fit, you drill a 32mm hole in the bottom of the gutter  and (self) lock it in. Once the water depth reaches 20mm, it flows at 1  litre per second through a connecting 20mm PVC pipe that is plumbed horizontally back to and then down the wall. It is very neat. I would supply  them free of charge. 
For the pergola area, a downpipe should have been fitted closer to the  roof valley. The pergola area inner wall guttering is harvesting an  apparently good sized roof area already and the excess from the other  two gutters and valleys feeding from an additional roof area is  obviously the problem. The roof valley corners should be the high  points. Again, the quick easy fix would be for me to send you some  fittings to fit to these areas.  
The Roofer has given you very good advice. It really comes down to cost  as to what you decide. At the moment I cannot publicly give too much  detail for obvious reasons but you would be the first to have the final  (uncoloured) production model. I just ask that you don't publish photos  or comment on design details pre release. Pipe, fittings (elbows etc)   and brackets would cost about $12 for each outlet. You would have to supply these.

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## DaleBlack

Hi guys 
The downpipes are hidden on top of the eaves, there is a rectangular hole in the back face of the gutter and of course through the fascia which then has a pipe that leads across the eave to the pipe attached vertically on the wall. I dont really like the idea as its hard to inspect if they are rusted or leaking themselves. I still need to check this in the roofspace as if they are leaking, then its not so much an overflowing issue afterall or at least not purely overflow. 
I will be contacting a roofplumber or two over here, already arranged so I will see what they say re the whole situation, gutter condition, size, position, also lack of soakwells in the area under the pergola and elsewhere around the house. If i do get new downpipes I might get those hidden existing downpipes replaced and the pipe routed from the outside down to the vertical pipe on the wall. All that would be needed is a small piece of metal riveted and siliconed to the existing holes. 
As for your device, firstly thanks for the offer re new product for now I will await a couple of quotes and onsite discussions. I was told by an insurance inspector who I initially called out (no damage so no claim) and is a builder himself that he would possibly fit 'pissers' in his words. Basically a output you have to cut a rectangular or circular hole in the gutter and then fit by way of rivet and silicone a little pipe fitting angled out away (in his case) from the house. They are supposedly at Bunnings but my first search found none. 
It seems though they would be 'always on', competing with the existing downpipes and thereby throwing water on the ground when it could be wisked away by the proper downpipes. 
Your device without wanting to preempt something, appears to effectively be purely an overflow gadget ie. water reaches a certain height then it cuts in to reduce gutter water volume but not before or always on. Only thing Iam unsure of is anything that directs water back to the wall, is that bad for the foundations? or given its only for overflow 'emergencies' its not an issue.

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## Danny

I guessed that the drainage method you described would be the only way possible. Interesting. 
Our outlet is actually designed to supplement the downpipe during downpours and is not designed to replace a downpipe. Piped water will generally be fed into the downpipe but it can be directed anywhere through larger ground level horizontal PVC pipe if need be. Unless blocked, a downpipe never contains less than two thirds air.  
I don't like the concept of the 'pissers'. Any water falling as a solid mass to a surface will have an erosive effect.   

> Only thing Iam unsure of is anything that directs water back to the  wall, is that bad for the foundations? or given its only for overflow  'emergencies' its not an issue.

  The pipe is directed horizontally to the wall and then down the wall to a discharge point, usually the downpipe.

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## DaleBlack

> Hi Dale, 
> Yes, pics help a little - not much room for a bigger section box gutter - but maybe your only choice if you don't want to replace the pergola!
> I'd go for a gutter section that sits on the support beams and joins with the house fascia as per: Problem with this is joining existing gutter (have to use a rainhead at downpipes each end)
> This would run three sides of the pergola - not an easy job - definately roof plumber - plus they may be able to offer a larger standard rollformed gutter that will fit and save all the hassle. I think WA does a large OG or Quad - may work - plus I'd increase your downpipe sizes on the three sides to at least 90mm round as the ones in photo look like 100x50? If you fit a larger standard gutter - make sure it has overflow slots or holes in the front to prevent backflow into the fascia side.
> Good luck!

  Hi Roofer, all 
A question specifically in regards to this part of the thread. 
Box Gutters VS continuing the std gutter around the pergola (see pergola images further up) 
Iam slowly in the process of obtaining quotes, one guy has recomended a box gutter design not disimilar to your drawing.  He says I could sit outside in a 20yr rain storm and no water will intrude anywhere. Another guy feels adament that its engineering overkill and just extending say quad gutter (which is larger than the style on there now) all the way round would be fine -(I would use overflow slots). 
The other piece of info since i started this thread is that the pergola area where 2 out of 3 of my overflowing into the eaves issues began, has 3 downpipes. I thought they were all working... One was sealed off from the gutter system, so only 2 out of 3 and anothers internal eave pipe is almost horizontal. These issues fixed even on just new std guttering would surely make an improvement. 
I am not one to be cheap necessarily I just like to weigh up the benefits of going all the way to a box gutter setup which is more costly.

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## The Roofer

Hi Dale, 
This highlights a problem with the capability of the plumbers giving quotes -   

> Another guy feels adament that it's emgineering overkill

  . Feeling adament is not enough - all they have to do is work out the exact catchment area, pitch etc and the gutter size is then worked out. This site has got a gutter calculator (it doesn't tell you where to put the drops) but will give a good reference to check the plumbers - go to SteelSelect® or another one is excellent that Danny linked in another thread - Ken Sutherland CV . 
You will have to work out the cross section area of the gutter, roof area draining into that section of gutter, drop pipe sizes, wind direction, and the calculator does the rest. Ask the plumber to work out the flow rates in a 1 in 20 year rainfall event? If he doesn't know - get another plumber to quote. 
Sorry I sound so negative on this, but any plumber should know how to work these calculations out without putting the questions back to you. Have a read of the 2nd link above by Ken Sutherland - there is heaps of good explanations on this subject to arm you with knowledge when receiving quotes and advice. 
I just did a rough guess on your roof - the calculator comes out with below 
<TABLE style="BORDER-BOTTOM: #c2c2c2 1px solid" border=0 cellSpacing=0 cellPadding=0 width="98%" height=300><TBODY><TR><TD style="BORDER-BOTTOM: #c2c2c2 1px solid; BORDER-LEFT: #c2c2c2 1px solid; BACKGROUND: #f5f5f5; BORDER-RIGHT: #c2c2c2 1px solid" class=content vAlign=top width="100%">Product Selection *OG Gutter (large capacity) - Generic profile selection* 
</TD><TD style="BORDER-RIGHT: #c2c2c2 1px solid" vAlign=top rowSpan=4 width=150 align=middle> </TD></TR><TR><TD vAlign=top><TABLE style="BORDER-LEFT: #c2c2c2 1px solid; BORDER-RIGHT: #c2c2c2 1px solid" border=0 cellSpacing=0 cellPadding=0 width="100%"><TBODY><TR><TD class=gutter_table align=middle>Maximum Gutter Area </TD><TD class=gutter_table align=middle>Gutter Freeboard </TD><TD class=gutter_table align=middle>Effective Gutter Area </TD></TR><TR><TD class=content height=60 align=middle>*7300 mm2* </TD><TD class=content align=middle>*10 mm* </TD><TD class=content align=middle>*6640 mm2* </TD></TR></TBODY></TABLE></TD></TR><TR><TD><TABLE style="BORDER-LEFT: #c2c2c2 1px solid; BORDER-RIGHT: #c2c2c2 1px solid" border=0 cellSpacing=0 cellPadding=0 width="100%"><TBODY><TR><TD class=gutter_table align=middle>Maximum Gutter Discharge Area </TD><TD class=gutter_table align=middle>Downpipes Required
(total catchment area) 
</TD><TD class=gutter_table align=middle>Downpipe Utilisation </TD></TR><TR><TD class=content height=60 align=middle>*44.6 m2* </TD><TD class=content align=middle>*5* </TD><TD class=content align=middle>*90%* </TD></TR></TBODY></TABLE></TD></TR><TR><TD><TABLE style="BORDER-LEFT: #c2c2c2 1px solid; BORDER-RIGHT: #c2c2c2 1px solid" border=0 cellSpacing=0 cellPadding=0 width="100%"><TBODY><TR><TD class=gutter_table align=middle>Downpipe Area Required </TD><TD class=gutter_table align=middle>Downpipe Type </TD><TD class=gutter_table align=middle>Minimum size required </TD><TD class=gutter_table align=middle>Downpipe Discharge </TD></TR><TR><TD class=content height=60 align=middle>*4285 mm2* </TD><TD class=content align=middle>*Square* </TD><TD class=content align=middle>*100x50 mm* </TD><TD class=content align=middle>*1.83 litres per second* </TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE> 
I used these figures below *Rollformer Selection:* 
Generic profile selection *Gutter Profile:*
OG Gutter (large capacity) *Slope/Wind:* 
Gutter Slope: >= 1:500 
Wind Conditions: Medium  *Catchment*: 
Roof Pitch: 15 degrees 
Catchment Area: 200 m2  *Rainfall:* 
State: WA
Location: Perth
Rainfall Intensity: 148 mm *Downpipe:* 
Downpipe Style: Square 
Hope this helps a bit?  :Biggrin:

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## The Roofer

Apologies Dale - I didn't answer the question directly. 
If none of the gutters and downpipes work in the calculators - then I would recommend going to the fabricated box gutter. 
Cheers

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## DaleBlack

Thanks Roofer, obviously just by looking at the attached images further up I can see a box gutter to be larger in carrying capacity, plus I assume using the std guttering with overflow slots would mean, my eaves wouldnt flood but water would pour out during a heavy downpour all into that paved are below making sitting there quite hard - then again I am often inside during storms so the main point is simply a system that does not overflow into eaves.. 
 The box gutter advocate as mentioned made a point you could sit there during a 1 in 20 yr storm. Not that you would want to pay a large amt just for that but he was obviously making the point if I take that option I will almost 100% have no problems. 
Are these box gutters able to be rolled or made in colourbond steel? as that will be what the rest of the guttering is. Or will it be zincalum that i will have to paint to match. 
Thanks for doing the calc and the other link.

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## Danny

The Roofer,
Good post! 
DaleBlack,
  Some notes.   

> The box gutter advocate as mentioned made a point you could sit there  during a 1 in 20 yr storm. Not that you would want to pay a large amt  just for that but he was obviously making the point if I take that  option I will almost 100% have no problems.

  I would hope so considering that standard roof drainage guttering has to be compliant with an area's 1:20 ARI and unless I am seriously mistaken, the compliance calculations for box gutters are generally calculated for a 1:100 ARI. This guy would more than worry me! 
A 1:20 ARI is calculated on a 5 minute rainfall intensity. For your area's 148 mm per hour ARI, you could experience a 1:20 year storm but perhaps get less than 15 mm of rain for the hour. 1:20 ARI's should be expected every 2-3 years.   

> (I would use overflow slots)

  Water overflowing through overflow slots is still considered overflow. Slotted gutters are recognised as non-continuous overflows in AS/NZS3500.3 (2003) Appendix G. The BCA 2007 also advised that "in heavy downpours a slotted gutter may be inadequate". I can, if needed, link test results for many manufacturers products that show their overflow slots to be hopelessly inadequate. 
Overflow provision should be made between the gutter and facia as required by the BCA unless the gutter front is lower than the back, which is now uncommon.  
Box Gutters... These generally require a 1:200 fall. You need to factor this slope re current distance between downpipes. 
A lot comes back to the roof area harvested as explained by The Roofer. You really need to know where the gutter high points are so that the people you ask to come around for advice/quotes are not guessing. It is rare for tradesmen to come around and donate their time to do water flow tests so that they can accurately find the solution to the problems. 
Figure 5 in the link below shows a diagram of a house with the downpipe locations and gutter high points shown. This is a Victorian Plumbing Industry Commission document but some of the information given should benefit you. Don't pay too much attention to the diagram in total though as some downpipe locations are not compliant with the BCA! A sad state of affairs.  http://www.pic.vic.gov.au/resources/...tormwater3.pdf  *EDITED* reference to slotted gutter compliance, too much conflicting advice from different regulatory bodies and manufacturers.

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## The Roofer

*     EDITED reference to slotted gutter compliance, too much conflicting advice from different regulatory bodies and manufacturers.
			
		  * 
This comment highlights the lack of unity in Australian plumbing regulations - worthy of a seperate thread - sorry Dale to highjack this - but this problem is very common all over the country where the simple hydraulics of water flow from roof tops  to guuters, to downpipes and stormwater are simply ignored, not checked, and it involves rollformers, the Steel Industry bodies, the plumbing Industry, BCA and Australian Standards. Most of the time is is bought up through customer complaints and in forums such as this - where it should never have been a problem in the first palce. 
A load bearing beam is stipulated and calculated by engineers depending on the locality Australia wide - but why doesn't the same sort of professionalism apply to rain water distribution from roof area????  
Thanks Danny for your insight into the box gutter problem above. 
P.S. Dale - please let us know how you go with this?<!-- google_ad_section_end -->

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## DaleBlack

Roofer, I will do, basically Ill end up with new guttering either way, maybe quad gutter which has a bigger cross section than whats on there or the box gutter as far as the patio area goes. Like i mentioned further up, I did find one of the 3 downpipes totally blocked off from the current system, so it was only running on 2.. One of those 2 has a eaves snorkel thats almost horizontal so further worsening drainage.

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## DaleBlack

Well my guttering and downpipes and patio roof is done, but i cant upload my images to show you! error message says ' exceeds limit quota by 2.92m' or something. What do I do? delete old attachments?

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## watson

What size are your pics Dale??

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## The Roofer

Looking forward to the pictures Dale!

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## DaleBlack

Hi all, I resized the pics to 800*600 and now they upload, a little unfortunate because i made a compilation image with before and after (1600*1200) and it may now be too small to view. See how you go. I am surprised even 1024*768 was deemed too big. 
The very first image has the old pics along the top and new replacement images on the bottom row. Click on them to view in their own screen. 
Anyway, I went with the box gutter around the patio, plus new colorbond sheets interspaced with wonderglass on the small patio roof. I may have to upload further images but the box gutter combined with the new sheeting cut to the right size has allowed a huge space for waterflow. Just so you know there are 3 downpipes servicing that small patio. If you look closly at the photos (particularly 3rd one along) you will see they actually cut a notch into the wood to fit the box gutter so a slightly different design to the one suggested in above posts. ie. it has a wide flat bottom but still with wings. 
I also ended up replacing every single gutter around the whole house with colorbond quad style which is slightly wider and bigger than the HK gutter it replaced.
Every existing downpipe was also replaced. In terms of extra capacity, one new downpipe was added along the rear run (see plans in earlier posts) and a spout in btw the 2 existing gutters on the long side run and another spout at the front of the house. 
Some valleys were also replaced. 
So far it seems a success, the people living there have not reported any overflowing issues since completion. In a while Iam on to the soakwell side of things.  
Let me know your thoughts including on whether they could have done better if you can see any issues or drawbacks.

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## The Roofer

Hi Dale, 
Really nice job - with the box gutters & big wings - plus 3 d/pipes - you won't have a problem - just leaves etc - but will be easier to clean now! The whole new pergola looks great also. The plumber did a good job fabricating the gutters plus the connection to the old one - professional.

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## DaleBlack

Hi Roofer 
When you saw the box gutter connecting to the 'old' one, its actually a new one as well. Outside the patio area all the gutters are brand new colorbond quad. When you look at the images you can see they are as new as the box gutter actually. The quad has a larger carrying capacity then the old HK stuff as well.

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## The Roofer

After nearly 5 months - I hope your gutter system is still working well! 
The only reason for this reply is the fact that most gutter systems being installed today in Australia seem to give problems in regard to overflow!
Since October last year I have investigated this problem extensively and only found one site that can give information on this problem! I have been in the roof and gutter industry for many years - yet the details provided on Gutters Overflowing is second to none - including all the ASA and other government groups. 
Why this big wrap out of the blue? Because the instigator of this site, comments on this forum and I have yet not to learn something on every post he makes. Many here will work out who this is - and acknowledge this fact. In the short time I have been a member - I have appreciated his valuable input and learnt so much on all his comments. 
If I had a large commercial guttering problem - this is where I would go to for help - and yet he posts here for nothing!  :2thumbsup:  :2thumbsup:

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