Browse Forums Building Standards; Getting It Right! Re: Downpipe Compliance - general discussion 61May 24, 2015 9:39 pm Thanks tlb. I wasn't aware of that. The new AS/NZS 3500.3:2015 replaces AS/NZS 3500.3:2003 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Downpipe Compliance - general discussion 62May 25, 2015 6:28 am SaveH2O goody59 Aurora where I am building have Estate recycled water to a couple of my outside taps, to my two toilets and one in the laundry. We also have solar gas boosted HWS. We had to achieve 6 star rating. You are NOT REQUIRED to have either a 2,000 litre water tank connected to all toilets or a gas boosted solar HWS if you are connected to recycled water. Because you are connected to recycled water, it fulfills that part of the 6 star requirement. If for example a customer wanted an instantaneous gas HWS and the house will be connected to recycled water, a builder is wrong in telling the customer that they must have a solar HWS or else a rainwater tank if they want an instantaneous gas HWS. Did Simmonds homes tell you that you must have either a gas boosted solar HWS or a 2,000 litre rainwater tank connected to all toilets to achieve the 6 star requirement? The builders had a solar has boosted HWS already in package so I didn't need to anything as the estate had rycycled water provided already. Re: Downpipe Compliance - general discussion 63Aug 09, 2015 9:22 am I thought I would post this to renew interest in this thread. I have been generously given a figure from a forum member of what I require for my minimum quad guttering size in cross sectional area for my roof drainage to comply with Code. I advised my builder that the roof drainage was non compliant if they used the industry standard in Victoria here of the 115mm quad slotted guttering that has a cross sectional area of 5,225 mm2. It was commented by our helpful Forum member that my 7 (Seven) downpipes as placed on my plan were all well placed but the issue was the gutter size.
The reply to my concerns from my builder was that they were issued with a building permit so then the roof drainage must be compliant so I should not concern myself. What utter b#**sh^^! I am building on a H2 site, highly reactive clay in the north area of Melbourne. Anyway, to the point of my post. I am trying to do the calculations of roof NOT being Code compliant myself with the help of Google but I am struggling. I wanted to put my figures out there so that I may be assisted in how my roof drainage is not compliant for all to see and learn from. I am in Melbourne(Wollert). What is my 20 year ARI? What is my 5 minute ARI Intensity? I think I require both to use in calculations. I will use the Victorian industry standard 115mm slotted quad guttering in the calculations and I know this has a cross sectional area of 5,225mm2. I will use in my calculations of my 7 apparently well placed down pipes (100mm x 50mm size?) I have a floor area of 223 sq m so I think I multiply that by 25% for a 25 degree pitch so I will add 55.75 for the pitch giving my 278 sq m now plus I have 450mm eaves all round so that area at 25 degrees gave me about another 40 sq metres for roof area. Total of those 3 added up now 318.75 sq m (223+55.75+40=318.75). How am I doing so far? How do I put all this together to give me the result that I am expecting, that is a short fall of gutter cross sectional area in mm2 of 775mm2. My figures should result in my gutters requiring a cross sectional area of 6,000 mm2. Thanks in advance to those that can place this data into a neat display of calculations that all can see. I am also not quite finished with my builder and their dismissive reply to my concerns. I know this roof drainage area of discussion is purely maths and there is only one right answer not just opinions. A roof is either Code compliant or it is not Code compliant. It can't be an opinion of compliance. I have kept all my builders replies and my emails of concern. If they supply a non compliant roof drainage system then it is recorded and will be used in evidence of negligence in any subsequent slab heave issue in an investigation of contributing causes of same. If I was my builder I would rather have a Code compliant roof supplied to clients, especially on a H2 site rather than end up on the wrong side of court action. Re: Downpipe Compliance - general discussion 65Aug 11, 2015 1:31 am goody59 I thought I would post this to renew interest in this thread. I have been generously given a figure from a forum member of what I require for my minimum quad guttering size in cross sectional area for my roof drainage to comply with Code. I advised my builder that the roof drainage was non compliant if they used the industry standard in Victoria here of the 115mm quad slotted guttering that has a cross sectional area of 5,225 mm2. It was commented by our helpful Forum member that my 7 (Seven) downpipes as placed on my plan were all well placed but the issue was the gutter size. The reply to my concerns from my builder was that they were issued with a building permit so then the roof drainage must be compliant so I should not concern myself. What utter b#**sh^^! I am building on a H2 site, highly reactive clay in the north area of Melbourne. Anyway, to the point of my post. I am trying to do the calculations of roof NOT being Code compliant myself with the help of Google but I am struggling. I wanted to put my figures out there so that I may be assisted in how my roof drainage is not compliant for all to see and learn from. I am in Melbourne(Wollert). What is my 20 year ARI? What is my 5 minute ARI Intensity? I think I require both to use in calculations. I will use the Victorian industry standard 115mm slotted quad guttering in the calculations and I know this has a cross sectional area of 5,225mm2. I will use in my calculations of my 7 apparently well placed down pipes (100mm x 50mm size?) I have a floor area of 223 sq m so I think I multiply that by 25% for a 25 degree pitch so I will add 55.75 for the pitch giving my 278 sq m now plus I have 450mm eaves all round so that area at 25 degrees gave me about another 40 sq metres for roof area. Total of those 3 added up now 318.75 sq m (223+55.75+40=318.75). How am I doing so far? How do I put all this together to give me the result that I am expecting, that is a short fall of gutter cross sectional area in mm2 of 775mm2. My figures should result in my gutters requiring a cross sectional area of 6,000 mm2. Thanks in advance to those that can place this data into a neat display of calculations that all can see. I am also not quite finished with my builder and their dismissive reply to my concerns. I know this roof drainage area of discussion is purely maths and there is only one right answer not just opinions. A roof is either Code compliant or it is not Code compliant. It can't be an opinion of compliance. I have kept all my builders replies and my emails of concern. If they supply a non compliant roof drainage system then it is recorded and will be used in evidence of negligence in any subsequent slab heave issue in an investigation of contributing causes of same. If I was my builder I would rather have a Code compliant roof supplied to clients, especially on a H2 site rather than end up on the wrong side of court action. I have this info regarding rainfall intensity in melbourne somewhere from memory it was 125 in 20 years. I will search for you. But remember the guttering requirements and the rainfall intensity don't rule the other out unless they are using a 'deemed to comply' method from an engineer Re: Downpipe Compliance - general discussion 66Aug 11, 2015 1:32 am goody59 I thought I would post this to renew interest in this thread. I have been generously given a figure from a forum member of what I require for my minimum quad guttering size in cross sectional area for my roof drainage to comply with Code. I advised my builder that the roof drainage was non compliant if they used the industry standard in Victoria here of the 115mm quad slotted guttering that has a cross sectional area of 5,225 mm2. It was commented by our helpful Forum member that my 7 (Seven) downpipes as placed on my plan were all well placed but the issue was the gutter size. The reply to my concerns from my builder was that they were issued with a building permit so then the roof drainage must be compliant so I should not concern myself. What utter b#**sh^^! I am building on a H2 site, highly reactive clay in the north area of Melbourne. Anyway, to the point of my post. I am trying to do the calculations of roof NOT being Code compliant myself with the help of Google but I am struggling. I wanted to put my figures out there so that I may be assisted in how my roof drainage is not compliant for all to see and learn from. I am in Melbourne(Wollert). What is my 20 year ARI? What is my 5 minute ARI Intensity? I think I require both to use in calculations. I will use the Victorian industry standard 115mm slotted quad guttering in the calculations and I know this has a cross sectional area of 5,225mm2. I will use in my calculations of my 7 apparently well placed down pipes (100mm x 50mm size?) I have a floor area of 223 sq m so I think I multiply that by 25% for a 25 degree pitch so I will add 55.75 for the pitch giving my 278 sq m now plus I have 450mm eaves all round so that area at 25 degrees gave me about another 40 sq metres for roof area. Total of those 3 added up now 318.75 sq m (223+55.75+40=318.75). How am I doing so far? How do I put all this together to give me the result that I am expecting, that is a short fall of gutter cross sectional area in mm2 of 775mm2. My figures should result in my gutters requiring a cross sectional area of 6,000 mm2. Thanks in advance to those that can place this data into a neat display of calculations that all can see. I am also not quite finished with my builder and their dismissive reply to my concerns. I know this roof drainage area of discussion is purely maths and there is only one right answer not just opinions. A roof is either Code compliant or it is not Code compliant. It can't be an opinion of compliance. I have kept all my builders replies and my emails of concern. If they supply a non compliant roof drainage system then it is recorded and will be used in evidence of negligence in any subsequent slab heave issue in an investigation of contributing causes of same. If I was my builder I would rather have a Code compliant roof supplied to clients, especially on a H2 site rather than end up on the wrong side of court action. I have this info regarding rainfall intensity in melbourne somewhere from memory it was 125 in 20 years. I will search for you. But remember the guttering requirements and the rainfall intensity don't rule the other out unless they are using a 'deemed to comply' method from an engineer Re: Downpipe Compliance - general discussion 69Aug 11, 2015 8:20 am See this document put out by the VBA in June 2015:
http://www.vba.vic.gov.au/__data/assets ... ainage.pdf On the first page second column it states: Part D1: Roof Drainage Systems – D1.2: General Requirements (incorporating Victorian variation): The design, construction, installation, replacement, repair, alteration and maintenance of a roof drainage system must be in accordance with AS/NZS 3500.3 or Section 5 of AS/NZS 3500.5 as appropriate. It states under Section 3 Roof Drainage Systems - Design: Clause 3.3.3 Meteorological Criteria - General (2003) This Clause has been rewritten to be mandatory, "Roof drainage systems shall be designed for the appropriate average recurrence interval (ARI)". SaveH20 wrote about this on this thread in a post dated Dec 29 2014 12.58 am Re: Downpipe Compliance - general discussion 70Aug 11, 2015 8:31 am Thanks Liliana. I would be looking for compliance then to Code and AS. I am a H2 site so that is why I have concerns and am not happy with my dismissive reply from my builders re this issue. Re: Downpipe Compliance - general discussion 71Aug 11, 2015 8:48 am The builder's reply is nonsense. Permits and certificates mean nothing unless they can prove compliance and often important things get overlooked. Our house was issued with a building permit even though it couldn't be built as drawn and it was issued with an Occupancy permit when it didn't comply with the Building Regulations so I wouldn't accept the builder's argument. goody59 I would be looking for compliance then to Code and AS. As far as roof drainage is concerned, my understanding of the VBA's position is that you would be looking for compliance with the Australian Standard, not the Building Code. Re: Downpipe Compliance - general discussion 73Aug 12, 2015 4:19 pm Liliana: Good posts. goody59: The answers to the questions you asked can be found earlier in this thread. goody59 The reply to my concerns from my builder was that they were issued with a building permit so then the roof drainage must be compliant so I should not concern myself. What utter b#**sh^^! I acquiesce your succinct summation. Your builder is living in the land of the fairies! Many thousands of new Victorian houses are built with non compliant roof - stormwater drainage every year and wrongly passed as compliant. The issue is endemic and not restricted to Victoria. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Downpipe Compliance - general discussion 74Aug 12, 2015 5:17 pm Firstly, SaveH20 posted the answer in a previous thread. Cut and pasted from the answer post by SaveH20 Given that the floor area is 223.4 sq m and the house has 450mm eaves (plus gutters), the roof area will be considerably more than 223.4 sq m. For this exercise, I will determine the Victorian roof drainage compliance for a 223.4 sq m roof plan area with the stated 25 degree pitch roof. Downpipes are located at the gutter's low points. The gutter's high points determine the gutter slope and the roof area drained to each downpipe. Downpipes DO NOT drain equal areas of roof. The 25 degree pitch roof is subject to a multiplier of 1.23 to allow for wind driven rain that results in more rain falling on one side of the roof. This means that the example's 223.4 sq m roof is factored as 275 sq m (rounded up) when determining eaves gutter compliance. The 7 downpipes would therefore drain an average factored roof area of 39.3 sq m in our example. If the house is in the Melbourne metro area, the 1:20 ARI (used to determine eaves gutter compliance) is 130 mm per hour, based on a 5 minute rain intensity. This is an average rain intensity of 2.166 mm per minute for 5 minutes. This example will also use the commonly used 115mm quad slotted gutters that have a cross sectional area of 5,225 sq mm. The cross sectional height is taken from 10 mm below the slots. In Victoria, if you have either 100 x 50mm rectangular or 90 mm round downpipes, the maximum factored roof area that can be drained to each downpipe in a 130mm per hour ARI with the gutter, downpipe and roof pitch combination used in this example is approximately 37 sq m to be compliant. To increase the maximum roof area drained to each downpipe as per this example, larger gutters are required. End of cut and paste. So what I take from that is that my 7 downpipes to be compliant will only drain by design to be compliant 37 sq m each. A shortfall for me of 2.3 sq m per downpipe so multiply that by 7 is 16.1 sq metres short fall for my roof drainage. Have I got that right SaveH20? I know I needed gutters with cross sectional area of 6000sq mm to have my roof drainage compliant. Regards Re: Downpipe Compliance - general discussion 76Aug 12, 2015 6:12 pm Trying to work out if my downpipes are compliant. I'm using the same builder as Goody I think, so I dare say mine won't be compliant either... How do you work out how much of the roof area each downpipe is draining? Is it possible to work it out based on the plans? Here is the plan showing my downpipe locations: https://dl.dropboxusercontent.com/spa/7 ... v07d7k.png Re: Downpipe Compliance - general discussion 79Aug 12, 2015 7:51 pm tom_air Trying to work out if my downpipes are compliant. I'm using the same builder as Goody I think, so I dare say mine won't be compliant either... How do you work out how much of the roof area each downpipe is draining? Is it possible to work it out based on the plans? Here is the plan showing my downpipe locations: https://dl.dropboxusercontent.com/spa/7 ... v07d7k.png Is that 7 downpipes? What is roof pitch? metal or tiles for roof? Do you have eaves? Save H20 has calculated that my roof drainage in non compliant. I would require a quad gutter with a cross sectional area of 6,000sq mm for my roof drainage to be compliant. I am on a H2 site too so that makes it even more important to have a roof drainage compliant roof. Re: Downpipe Compliance - general discussion 80Aug 12, 2015 8:25 pm goody59 So what I take from that is that my 7 downpipes to be compliant will only drain by design to be compliant 37 sq m each. A shortfall for me of 2.3 sq m per downpipe so multiply that by 7 is 16.1 sq metres short fall for my roof drainage. Have I got that right SaveH20? Yes...but the figures aren't exact because I didn't know the exact roof area...but the drainage will come up short because the figures will be close and the discrepancy is large. The calculations factor the maximum roof area that can drain to each downpipe, it is not the average drained to each downpipe because downpipes invariably drain different size roof areas. Your builder will (if willing) be able to tell you the roof space area and the roof catchment (factored) area. If you return to fzxbeetle's opening post on this thread, you will see that he has posted his roof areas as given to him by his builder. Note that the builder (Henley) were wrong with their drainage calculations as per those figures because they basically didn't have a clue. The VBA technical solution sheet 0.04 that I have linked below also discusses roof drainage compliance with an example. Note that the technical solution sheet is a re-vamp of a former Victorian Building Commission technical solution sheet but it is a poor attempt...some things like the roof slope factoring isn't properly addressed and they have even left a downpipe off the last house diagram on page 6! Good on 'em. I give it a 4/10. http://www.vba.vic.gov.au/__data/assets ... mwater.pdf 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Building Standards; Getting It Right! It's all good. You can get both wye piece and the coupling with or without thread. The cost difference is negligible and means the plumber only has to carry the single… 1 5197 I can totally relate to your shed project struggles—I recently tackled a similar ordeal, and it was quite the journey. Navigating through all those regulations and hoops… 4 8602 |