Browse Forums Building Standards; Getting It Right! Re: Downpipe Compliance - general discussion 21Dec 11, 2014 7:37 pm 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 22Dec 11, 2014 8:49 pm ------------------------------------------- Build Thread - Mainvue Emporio ER430 KDR https://forum.homeone.com.au/viewtopic.php?f=31&t=76790&p=1332227&hilit=mainvue#p1332227 Re: Downpipe Compliance - general discussion 23Dec 13, 2014 3:26 pm 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 29Dec 28, 2014 11:58 pm 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 31Jan 13, 2015 10:03 pm 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 33Jan 14, 2015 2:40 am This should interest a few. Storm water (roof) drainage compliance does not guarantee good design, in fact, a good design may not necessarily be compliant. An example of a very common bad design that is nevertheless (often) still compliant can be seen in the photo below. Who's going first with some answers? 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 34Jan 14, 2015 7:16 am Let me try... 1. Sections of roof that drain to a lower section of roof must be included in the calculation for the drainage needs of the lower roof area. 2. Run-off from walls must be included in drainage design 3. There are inadequate downpipes on the Garage Re: Downpipe Compliance - general discussion 35Jan 14, 2015 11:14 am tlblhayward 1. Sections of roof that drain to a lower section of roof must be included in the calculation for the drainage needs of the lower roof area. 2. Run-off from walls must be included in drainage design Both of the above are correct but let's assume that both calculations were included in the roof drainage design as required by the regulations and the roof area harvested is compliant. tlblhayward 3. There are inadequate downpipes on the Garage Very close. You cannot see a downpipe but the downpipe is frequently at the end of the gutter (LHS in this instance) and often around the corner. I will try to get a better photo when I have time. BAD DESIGN: (previous photo) A downpipe drains an upper roof area to a spreader that discharges the highly concentrated flow to a small section of gutter on the RHS. The water hitting the abutting wall during wind driven rain travels as a concentrated flow down the wall - garage roof intersect to the end of the gutter on the RHS. Logically, the downpipe should be fitted at the gutter's RHS but because aesthetics often subjugate function, the builder/architect/designer will position the downpipe away from the front to maximise the street appeal. This is a common 'trick' used on display homes but the "design" is then carried over to the customer's house. The result is that during heavy rain, the gutter will overflow where the concentrated flow discharges to the gutter. I see it all the time. Compliant?...YES. Good design?...NO. The photo below shows good design. Not too hard to do...and it still looks good! 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 37May 18, 2015 10:11 am tlb, because the plans you have posted do not show the gutter's high points, the harvested area of roof that each individual downpipe drains cannot be determined. Each individual roof area harvested to each downpipe must be compliant with each State's applicable regulations but compliance is ignored by numerous builders in Victoria when they use the technically inferior and cheaper to install BCA alternative solution. As per what I have already posted in this thread, Victorian roof drainage compliance is clear cut: SaveH2O "Plumbing practitioners in Victoria are required to install roof drainage installations in accordance with AS/NZS 3500.3 Plumbing and drainage Part 3: Stormwater drainage the relevant section of AS/NZS 3500.5 Plumbing and drainage Part 5: Housing installations as prescribed in the National Construction Code Volume Three - Plumbing Code of Australia (PCA) along with HB39 – 1997 Installation code for metal roofing and wall cladding and SAA/SNZ HB114:1998 Guidelines for the design of eaves and box gutters as prescribed within the Plumbing Regulations 2008. This is as a result of the VBA implementing a Victorian variation within the PCA under Part D1to remove the BCA as a Deemed to Satisfy requirement for roof drainage installations." SaveH2O The BCA was developed to replace local and State regulations and evolved to a performance based document about 15 years ago. In 2008, the PCA (2004 edition) was adopted into the Plumbing Regulations (2008). The PCA (2004 edition) made no reference to the BCA as a DTS provision for roof drainage systems. On May 1 2011, the PCA was introduced into the National Construction Code (NCC) as Volume 3. At the time of adoption, Victoria introduced a variation into the DTS provisions of Part D1 to exclude the BCA as a DTS provision for roof drainage systems. Note: The National Construction Code (NCC) brings together the Building Code of Australia (BCA) volumes 1 & 2 and the Plumbing Code of Australia (PCA) volume 3. Since 2011, there have been no changes made to the Victorian variation contained within Part D1 of the PCA and it currently still excludes the BCA as a provision of Part D1 of the PCA. In other words, Victoria has at no time adopted the BCA as a DTS provision for roof drainage systems. The BCA DTS provision for roof stormwater drainage is inferior to AS/NZS 3500.3 Plumbing and drainage Part 3: Stormwater drainage and the variation to exclude the BCA as a DTS provision for roof drainage systems was IMHO a wise decision. The BCA deemed to satisfy solution is technically inferior and I have also explained why in this thread. 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 38May 18, 2015 11:07 am Thanks SaveH20... words of wisdom (as per usual!). Re: Downpipe Compliance - general discussion 39May 20, 2015 8:05 pm I have a proposed dwelling to be built by Simonds homes. Building in Wollert Melbourne in Aurora Estate. 223.4 square metres floor area but have 450mm eaves all round, colourbond with 25 degree pitch. I will assume the proposed guttering will be the standard and so will the downpipes. I have 7 downpipes on the plan I have but the final plans and engineering of slab and drains are not complete. Soil test and land contour survey being conducted in the next week or so. So seven downpipes, am I looking ok at this amount or will I require additional? I have a PDF of all my plans but there are a number of pages and I have no idea how to break it up and just post floor plan page of the total file. Re: Downpipe Compliance - general discussion 40May 21, 2015 2:23 am Hi goody59, The roof area when looking at a house plan is the roof circumference that also includes the gutters. Because houses are usually not singularly rectangular in shape, it is not possible in this instance to state the actual roof plan area but this is easily calculated if the plans are available. 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. 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 4933 For anyone that comes across this issue in the future - Just did what aussieta said and found a plumber to inspect it and sign off on it. Was difficult to find someone to… 3 7044 |