Browse Forums Owner Builder Forum Re: Roof Plumbing Plan 2Mar 01, 2014 11:48 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: Roof Plumbing Plan 5Mar 02, 2014 2:32 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: Roof Plumbing Plan 6Mar 02, 2014 8:40 pm SaveH20, again, you are a STAR! Yep, I'm going to have asphalt shingles, and I intend to install myself, so I can ensure the flashing is laid to handle overflow of the gutters. I'll have to take a look at this gutter pumper! I was intending on building the underground concrete water tank myself, since my uncle has built about 3x 10kL and 5x20kL tanks. He has the formwork already made up, and a lot of experience as well. I will definitely be trawling through your posts about water tank design to get some excellent tips. Once again, thanks for taking the time to reply to this thread. It's pretty amazing, to be honest. Well done for contributing to everyone's knowledge. THANKS! Re: Roof Plumbing Plan 7Mar 02, 2014 9:36 pm Oh yeah, also, guess I am being conservative with the 40sqm, rather than the 45sqm. I'm ok with this, if it means my roof doesn't leak! And you're correct, 1:20 ARI is the bare minimum. 1:350 fall on the gutters - I can do that. That's like 3mm for every metre. Surely that is not hard to install, right? Re: Roof Plumbing Plan 8Mar 03, 2014 3:15 am The minimum 1:500 is only 2 mm per metre and so having 1:350 (3 mm per metre) isn't much of a step up. It's the minimum that I would have. Just have the spreaders as close as practicable to the downpipes. You have obviously worked out your best downpipe locations. You don't have to go up much in gutter cross sectional size on the lower roof to be ok for the larger roof area compliance as you are already at 45 sq m. There are many gutters to choose from. Going to the 100 mm round downpipes with the bigger gutters on the lower roof also has other advantages. The fall on stormwater pipes is a minimum of 1:100. Plumbers mostly use (cheap and flimsy) 90 mm stormwater pipe draining to 150 mm DWV, depending on the flow rates. The regs are in section 7 & 8. Read this post re gluing PVC pipe. It is easy to weaken the thin stuff. viewtopic.php?p=941557#p941557 If you get a chance, you should find bashworth's blog full of handy hints and interesting stuff. Well worth a read. http://www.anewhouse.com.au/ Do you know that plumbing in Victoria is strictly regulated? Some other States (and the ACT) allow you to do the work that you are intending but not here. You don't want to get caught out with compliance issues re certificates etc. SaveH2O This will be a quick fire reply as I am way behind with my work and about to go out. The best laid plans of..... 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: Roof Plumbing Plan 9Mar 03, 2014 12:18 pm Hi David, Also check section 5, surface drainage systems - design. Talking about plumbing regulations...Did you notice anything 'unusual' about the information in table 3.3? HUGE hint - 90 mm downpipes and the heading indicating required minimum downpipe sizes. 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: Roof Plumbing Plan 10Mar 09, 2014 6:22 am Thanks SaveH2O. Yes, I've been reading your posts about pipes leaking with interest. I could think of nothing worse than pipes leaking within your slab. It would be a nightmare. I will certainly specify DWV pipes for my stormwater system. This is opposed to "90mm stormwater pipe" that you talk about here: viewtopic.php?f=31&t=68030&p=1098749&hilit=onsite+stormwater+detention#p1098749 I guess I have to be just as vigilant when the plumber installs the pipes for the black and grey water plus vents - make sure they use the DWV and that the joints are done correctly. I wonder how the plumbers will feel with me telling them how to do their job? Will have to discuss it at the quote stage, when everyone is nice! To be honest, my eyes glazed over on Table 3.3. It took me a long time to figure out what was going on, but then only looked at the line that was relevant to me, and moved on. Looking back at it, it has a lot of very similar options, and I tend to wonder why so much detail is needed? AS3500.3 is a very good standard, if you ask me. The examples in there are very easy to follow. But, at the moment, I am wading through Onsite Water Detention. This on the otherhand, is Crazy, with a capital K. I'm surprised how much work gets put into the hydraulics. I shouldn't really be, but I am. Reading up on the cost of OSD is staggering. Thanks for your advice, SaveH2O! Re: Roof Plumbing Plan 11Mar 09, 2014 6:47 am Oh, and I was wondering about the ARI for Melbourne, and how I could get more up-to-date information, if I were using obsolete data. I think the data in AS3500 is from the Annual Rainfall and Runoff Study from 1987 (AR&R87). This data is available in a much easier format on the Bureau of Meteorology's website, plus more data from 2013! http://www.bom.gov.au/water/designRainfalls/ifd/ I couldn't figure out why the 2013 data I was getting, was so far off the 1987 data. I just realised that I have to multiply the X min duration by 60/X to get mm/hr. For instance, a 20yr ARI, 5min duration in the 2013 data for my latitude/longitude is: 5%, 5min = 11mm x 60/5 = 132mm/hr. Have I figured this out correctly, SaveH2O? Re: Roof Plumbing Plan 12Mar 09, 2014 4:36 pm akapacker But, at the moment, I am wading through Onsite Water Detention. This on the otherhand, is Crazy, with a capital K. I'm surprised how much work gets put into the hydraulics. I shouldn't really be, but I am. Reading up on the cost of OSD is staggering. Are you are required to have Onsite Stormwater Detention (OSD). Yes/No. If Yes, then the first thing to do is find out from the council the maximum discharge rate allowed. This is usually stated as litres per second (lps). If the maximum is given as let's say 5.5 lps, then the maximum overflow rate will be 330 litres per minute (lpm). If your 1:20 ARI roof run off is calculated as let's say 640 lpm (I haven't read back to get an accurate figure), then a hydraulic engineer will calculate the detention capacity (detention compartment) needed to absorb the 310 lpm excess flow with a safety margin. It must be understood that the roof run off will most likely already be in excess of the overflow capacity prior to the rain intensity reaching a 1:20 ARI status. In the above scenario, the detention capacity required may be 2,500 litres. An above ground detention tank has a small overflow pipe at the bottom of the detention compartment and a larger overflow pipe at the top. The smaller pipe's flow rate increases as the detention compartment fills because it operates with a variable hydraulic head. If the smaller overflow outlet is meshed and the mesh gums up, the upper pipe will be a safety valve of sorts. I say "of sorts" because the overflow capacity will not match the inflow. The upper pipe is fitted to give a safety margin in case there is a prolonged storm, not because of any consideration given to the smaller pipe's mesh clogging but this scenario must be considered in a well designed system. It is best to use a flap valve that allows the smaller overflow pipe to discharge into a junction fitted to the larger overflow pipe connected at the top. You can see in the above photo that a 90 mm stormwater overflow pipe drains into a 100 mm DWV fitting. The smaller detention overflow pipe drains into an invert taper that connects to the DWV fitting. EDIT: Can you clear up the reference to OSD and your intended use of the buried concrete tank thanks. I had assumed that this was going to be a retention tank. If the concrete tank is in fact intended to be a detention tank, then a whole lot of new dynamics apply such as slope, pipe locations etc. The concrete tank's overflow cannot be additional to a detention tank's hydraulic plan if it is intended to be a retention tank. Have you read the link below that mentions nominal Vs actual pipe sizes and AS2200 flow rate compliance? For your roof area, '90' mm uPVC stormwater pipe would be borderline for compliance anyway. viewtopic.php?p=1145148#p1145148 SaveH2O Talking about plumbing regulations...Did you notice anything 'unusual' about the information in table 3.3? HUGE hint - 90 mm downpipes and the heading indicating required minimum downpipe sizes. Answer: The second column's header states: "Internal size of vertical downpipe mm". These figures refer to the MINIMUM size! The internal diameter of most 90 mm uPVC stormwater pipe is 86.2 mm! 3.3 is easy to read, the gutter's cross sectional area is on the left side. Once you know that, you just look at the RHS for the downpipe size. Just make sure you look in the 1:500 slope or greater column. Re the ARI, the BOM announced a while ago that they were moving to a new system to determine a Intensity Frequency Duration (IFD). I like the old ARI system as it is easier to explain and quicker to look up but the IFD system is more zone specific. AS/NZS 3500.3 stormwater drainage compliance still refers to ARI, the Standards haven't changed. The links below lets you work out your area's IFD. Note that AS/NZS 3500.3:2003 Appendix D states the guidelines for determining IFDs. http://www.bom.gov.au/hydro/has/cdirswe ... webx.shtml Click "Create an IFD". The link above is off bashworth's blog...a gold mine of information. http://www.anewhouse.com.au/category/su ... ity/water/ akapacker I couldn't figure out why the 2013 data I was getting, was so far off the 1987 data. I just realised that I have to multiply the X min duration by 60/X to get mm/hr. For instance, a 20yr ARI, 5min duration in the 2013 data for my latitude/longitude is: 5%, 5min = 11mm x 60/5 = 132mm/hr. Have I figured this out correctly, SaveH2O? Yes. Well done. 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: Roof Plumbing Plan 13Mar 11, 2014 9:34 pm Hi SaveH2O, Once again, thanks for the advice. I might start a new thread for Onsite Stormwater Detention, to keep this thread pure. I'm beginning to understand why you recommended against underground water tanks. But, I'll elaborate more in the new thread. Re: Roof Plumbing Plan 14May 02, 2014 11:33 am Hi akapacker, Just to let you know the spreader bars are a great idea as I often see the asphalt shingles deteriorate prematurely where the water off the main roof is let to run off the roof below. However, the MOST IMPORTANT thing is to use the best underlay. IKO Roof guard premium synthetic underlay will last a lifetime. Even if the shingles start to deteriorate the underlay will stop any water from entering. We have stopped using the asphalt saturated felt paper because it breaks down easily and can leak. It is just PAPER with an asphalt saturant coating. It is worse in the areas where water builds up. If your whole roof is covered in the synthetic underlay and the valleys are lined with IKO Armourguard rubberised membrane you will never have a problem. I am replacing a block of ten units where no underlay was used on a 10 degree pitch - huge mistake. Low slope roofs need "Rubberised Membrane" between 8.5 and 18.5 degree pitch & valleys. All other areas need premium Synthetic underlay - like IKO Roof Guard synthetic underlay. Kind regards, Richard. Richard Larner - Asphalt Shingle Roofing Expert. Supplying DIY roofing advise tailored to Australia's unique conditions. Re: Roof Plumbing Plan 15May 10, 2014 1:01 pm I've been reading this thread with interest as I'm in the process of doing the same as akapacker and have worked out my downpipes pretty much the same. One thing I am confused with though is the slope factor. Any of the slope or pitch factor charts I have seen say that a roof with a pitch of 25º has a slope factor of 1.103 not 1.23 ? I'm about to work out the slope factor for my roof which is 15º and accordingly the SF should be 1.036 or is this the wrong figure ? I thought it was as simple to work out your actual roof area by multiplying the plan area x the SF. What am I missing here ? Stewie Re: Roof Plumbing Plan 16May 10, 2014 1:11 pm Stewie D One thing I am confused with though is the slope factor. Any of the slope or pitch factor charts I have seen say that a roof with a pitch of 25º has a slope factor of 1.103 not 1.23 ? Hi Stewie, AS/NZS 3500.3:2003 Section 3, table 3.2 is my reference for eaves gutter roof area factoring. 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: Roof Plumbing Plan 17May 10, 2014 2:34 pm The former Victorian Plumbing Industry Commission (PIC), now incorporated into the new Victorian Building Authority (VBA), had a technical solution sheet that explained the factoring by example. It now simply refers to AS/NZS 3500.3 and HB114...a handbook! Go figure!!! I checked the NSW Office of Fair Trading website and they now also use the 'upgraded' technical solution sheet. http://www.pic.vic.gov.au/__data/assets ... water3.pdf Nevertheless, if you calculate the roof plan area, you will find that it is 185 sq m (two areas of 10 x 15 & 5 x 7). If you then add up the catchment areas shown, they total 222 sq m. The roof pitch is still stated in the linked document as 23 degrees. This is factored by 1.21 as per AS/NZS 3500.3 (calculation example no longer shown on technical solution sheet) but the doc still states that the maximum roof area drained to the indicated gutter's cross sectional area and downpipe size is 47 sq m. Given that the average of the 5 roof catchment areas shown is 44.4 sq m, you can see that the 23 degree roof pitch shown in the example has had a factoring of 1.21. 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: Roof Plumbing Plan 19May 10, 2014 3:17 pm Stewie D Aha ! 15º Roof slope factor = 1.13 Correct. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. In my experience roof is essential element of the building envelope and hence a common property and should be covered by owners corporation however a detailed review of… 3 6199 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 7078 5 3795 |