Browse Forums Building A New House Re: Downpipe at facade 2Aug 19, 2021 6:32 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 at facade 3Aug 19, 2021 7:02 pm Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Downpipe at facade 6Aug 19, 2021 8:11 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 at facade 8Aug 19, 2021 11:59 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 at facade 9Aug 20, 2021 4:20 am SaveH2O boang Is it ok to remove this downpipe? Because our builder says we cant. I'll first explain the roof drainage regulations and will also assume that you are in Sydney metro. Roof drainage regs for eave gutters are based on a 1:20 year storm event referred to as either an Average Recurrence Interval (ARI) or an Intensity Frequency Duration (IFD). Your 1:20 is most likely to be 200 mm/hr which is based on an average 5 minute intensity of 3.33 mm/minute and it is this 5 minute average intensity that determines qualification as a 1:20 storm event. The regulations also factor your roof pitch for wind driven rain and your 24.5 degree roof pitch has a multiplier of 1.23 that determines the roof harvest areas. In other words, 10 sq m is calculated as being 12.3 sq m. These figures are used to determine the maximum roof area serviced by each downpipe and the gutter's cross sectional area plus the downpipe size. Downpipes are positioned at the gutter's slope lowest point, the slope's high point determining the areas of roof draining to each downpipe. Note that I can only assume where the gutter's high points are and so I am unable to absolutely determine the exact factored roof harvest areas draining to each downpipe. If you remove the downpipe, the gutter would pool water, dam debris and probably overflow. To help prevent this, the gutter would need resloping, a not too difficult problem. There are 8 flow restricting corners between the two nearest downpipes and the current downpipe is positioned with 4 of those corners on either side. This is good but the balcony downpipe will receive little water from the RHS and is poorly positioned for best function. HOWEVER, if the downpipe was removed and the gutter resloped with the high point at the sitting room and B1 intersect, the factored roof area draining to the B1 downpipe would be about 10 sq m in excess of compliance. If the high point was moved further along B1 wall to make the roof harvest area draining to the B1 downpipe compliant, you would then have 5 corners and about 8.5 metres of guttering plus minimal roof harvest area compliance from the high point to the sitting room downpipe. The high point between the sitting room and the B3 downpipes could however be moved closer towards the balcony to ensure harvested roof area compliance for the sitting room downpipe if needed. Thanks Very Much SaveH20! This very informative. So you mean to say that we can remove the balcony downpipe, do gutter resloping and maybe add 1 downpipe at the sitting side? like this(see picture) Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Downpipe at facade 10Aug 20, 2021 11:12 am NO. It would be easier to alter the gutter's high point. Firstly, I don't know your gutter's cross sectional area but I am confident in the minimum gutter size used as per the BCA table 3.5.3.2a. You might however have larger gutters than required but that is highly unlikely unless you have specifically optioned them. It is unlikely that the builder has used the Australian Standards over the laxer BCA regs which I have assumed he has used but nevertheless my answers (which are per the BCA) and the gutter's high points need checking to determine the roof harvest areas currently draining to the front three downpipes before resloping can be done. This is easy when on site. Rainwater currently collected by the balcony downpipe will have to be collected by the B1 and sitting room downpipe if the balcony downpipe is removed and the gutter resloped. The current downpipe is functionally good because it allows for an uncompromised gutter slope which is important when there are a lot of corners but the price is paid in lost aesthetics. B1 downpipe. I don't know where the current front high point is but it is (logically) more likely to be at B1 left front corner (inline with the WIR wall) rather than the corner at B1 and the sitting room in order to comply with the maximum roof harvest area allowed to drain to this downpipe. If this (assumed) current high point is retained, then there would be 5 corners between the high point and the downpipe at the sitting room which isn't good but if the high point was moved to the B1 and sitting room corner (which will also deliver less water to the sitting room downpipe which is good), the B1 downpipe would most likely be draining a non compliant roof harvest area. This could most probably be overcome by moving the high point between B1 and the ensuite further towards the front. Sitting room downpipe. This will also be collecting more water but the high point between the sitting room and the downpipe at B3 can be moved closer to the front as an adjustment if necessary which would also address the BCA reg below. 3.5.3.5 Downpipes — size and installation Downpipes must— (a)not serve more than 12 m of gutter length for each downpipe; and (b)be located as close as possible to valley gutters; and (c)be selected in accordance with the appropriate eaves gutter section as shown in Table 3.5.3.2a to Table 3.5.3.2c. Explanatory information: A maximum 12 m gutter length served by each downpipe is to ensure effective fall and adequate capacity to discharge all water anticipated during a storm having an average recurrence interval of 20 years. The applicable roof drainage regulations are found in the BCA at 3.5.3 which is Part 2 of the NCC. This document can be downloaded free of charge. 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 at facade 11Aug 20, 2021 11:31 am SaveH2O NO. Firstly, I don't know your gutter's cross sectional area but I am confident in the minimum gutter size used as per the BCA table 3.5.3.2a. You might however have larger gutters than required but that is highly unlikely unless you have specifically optioned them. It is unlikely that the builder has used the Australian Standards over the laxer BCA regs which I have assumed he has used but nevertheless my answers (which are per the BCA) and the gutter's high points need checking to determine the roof harvest areas currently draining to the front three downpipes before resloping can be done. This is easy when on site. Rainwater currently collected by the balcony downpipe will have to be collected by the B1 and sitting room downpipe if the balcony downpipe is removed and the gutter resloped. B1 downpipe. I don't know where the current front high point is but it is (logically) more likely to be at B1 left front corner (inline with the WIR wall) rather than the corner at B1 and the sitting room in order to comply with the maximum roof harvest area allowed to drain to this downpipe. If this (assumed) current high point is retained, then there would be 5 corners between the high point and the downpipe at the sitting room which isn't good but if the high point was moved to the B1 and sitting room corner (which will also deliver less water to the sitting room downpipe which is good), the B1 downpipe would most likely be draining a non compliant roof harvest area. This could most probably be overcome by moving the high point between B1 and the ensuite further towards the front. Sitting room downpipe. This will also be collecting more water but the high point between the sitting room and the downpipe at B3 can be moved closer to the front as an adjustment if necessary which would also address the BCA reg below. 3.5.3.5 Downpipes — size and installation Downpipes must— (a)not serve more than 12 m of gutter length for each downpipe; and (b)be located as close as possible to valley gutters; and (c)be selected in accordance with the appropriate eaves gutter section as shown in Table 3.5.3.2a to Table 3.5.3.2c. Explanatory information: A maximum 12 m gutter length served by each downpipe is to ensure effective fall and adequate capacity to discharge all water anticipated during a storm having an average recurrence interval of 20 years. The applicable roof drainage regulations are found in the BCA at 3.5.3 which is Part 2 of the NCC. This document can be downloaded free of charge. Thanks Very much for the information. Really appreciate it SaveH20. Im asking our builder what gutter specs they are using for the build. What gutter specs is it needed in order to remove that downpipe? or is there no other way/option to remove that downpipe. Thanks very much save for all this info and answering all my queries. Re: Downpipe at facade 12Aug 20, 2021 11:38 am boang What gutter specs is it needed in order to remove that downpipe? or is there no other way/option to remove that downpipe. Changing gutters is expensive, you have what you have. Two high points would need to be moved and more than likely the third one on the front as well. Download the BCA which is Part 2 of the NCC, everything is there. 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 at facade 13Aug 20, 2021 12:25 pm SaveH2O boang What gutter specs is it needed in order to remove that downpipe? or is there no other way/option to remove that downpipe. Changing gutters is expensive, you have what you have. Two high points would need to be moved and more than likely the third one on the front as well. Download the BCA which is Part 2 of the NCC, everything is there. Hi Save, I current draw the gutter length(in yellow hightlight) apparently i got Total length of 12220. If ill adjust the down pipe a little bit to have below 12meters. Is this good enough for the standard? Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Downpipe at facade 14Aug 20, 2021 12:51 pm It also comes back to the maximum roof harvest area allowed which is the most important. Read my posts again in conjunction with BCA 3.5.3.5 but the plumber will have to check the roof harvest areas and the gutter high point positions.to map changes. 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 at facade 15Aug 20, 2021 12:54 pm SaveH2O It also comes back to the maximum roof harvest area allowed which is the most important. Read my posts again in conjunction with BCA 3.5.3.5 but the plumber will have to check the roof harvest areas and the gutter high point positions.to map changes. Ok sorry, ive been reading the BCA 3.5.3.5 sorry ive missed out some infos ill try to ask my builder about this one Re: Downpipe at facade 16Aug 20, 2021 4:22 pm The tables for your 1:20 ARI and corresponding maximum roof catchment areas are 3.5.3.2a and 3.5.3.2b. Just remember that the roof "catchment" area is the area calculated after multiplying by 1.23 to allow for wind driven rain on your roof slope. The roof slope multiplier is shown in AS3500.3 which the BCA refers to. 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 at facade 18Aug 20, 2021 4:40 pm You have to buy it, it is expensive. Try Googling "eaves gutter catchment area slope factor". Page 3. https://www.vba.vic.gov.au/__data/asset ... system.pdf Note that the other calculations in the VBA pdf are all done to the Australian Standards as Victoria has never adopted the inferior BCA as a Deemed To Satisfy (DTS) provision for roof drainage systems. 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 at facade 19Aug 20, 2021 4:52 pm SaveH2O You have to buy it, it is expensive. Try Googling "eaves gutter catchment area slope factor". Page 3. https://www.vba.vic.gov.au/__data/asset ... system.pdf Note that the other calculations in the VBA pdf are all done to the Australian Standards as Victoria has never adopted the inferior BCA as a Deemed To Satisfy (DTS) provision for roof drainage systems. ill have to calculate my roof plan area. so that I can get the total roof catchment area 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 Dear Members I have to decide the Facade column size. My custom builder standard is 350mm with rendering, but i asked for 470mm plus stone or tiles and yet to get… 0 7508 |