What bears more weight NCC or Aus Stds?
Browse Forums Building Standards; Getting It Right! Re: Hierarchy 2Sep 28, 2015 7:01 pm The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Hierarchy 4Sep 28, 2015 8:24 pm The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Hierarchy 6Sep 28, 2015 9:13 pm The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Hierarchy 8Sep 30, 2015 1:21 am 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: Hierarchy 11Sep 30, 2015 10:36 pm Crazyk Go figure this. VBA plumbing technical dept say that NCC does not apply in Vic ! I explained this in my last post! The BCA is Part 1 and Part 2 of the NCC. The PCA is Part 3 of the NCC. Please read my last post again. NOTE: Allowing plumbers to use "their best judgement and experience instead of a calculated method" is an exercise fraught with peril as is evidenced by your situation...and of course they then sign off on their own work that is subsequently blessed by a surveyor who works for the builder. 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: Hierarchy 12Oct 01, 2015 6:30 am Sorry I skipped straight over that reference. I might also add that I probably wouldn't win in VCAT because although sections 5.4 &5.5 are contradicting each other they have in fact complied with one section meaning they are able to sign off. Doesn't matter that it's technically not going to work. I argued with him and said I'm happy with the experience and best judgement bit, however if I was a plumber there is a really quick sanity check. Min grade 1:100 Discharge capacity DN100 - 480l/m for approx 240m2 of catchment So if I have 330m2 I'm going to be in a bit of trouble. He said good point. Case closed, plumbers are just like the rest of them and try to save literally $50 in a $5000 and sign off undersized (not non compliant) systems In any case the Concreter doing my new footpaths was nice enough to put in an additional kerb outlet so I'll just connect that in at a later date. Re: Hierarchy 13Oct 01, 2015 1:53 pm Crazyk I might also add that I probably wouldn't win in VCAT because although sections 5.4 &5.5 are contradicting each other they have in fact complied with one section meaning they are able to sign off. Doesn't matter that it's technically not going to work. Exactly. The referenced Australian Standards are poorly written and AS2200 not being referenced is a bad oversight. AS2200 should be legislated, it is staggering that it isn't. As is, it is left to the builder's and plumber's social conscience (and best judgement) as to whether the right thing is done...provided they know what the right thing is of course and how can the use 'best judgement' if they don't reference AS2200? The time and money they save themselves by installing below capacity yet 'compliant' drainage is not much and at some stage, you will experience a 1:20 or greater ARI...and you won't have to wait 20 years for it either! I think that you could argue that the design is not competent because AS2200 was not referenced, regardless of whether AS2200 was referenced or not in the contract. You also need to check your roof drainage for AS compliance. Most builders in Victoria wrongly reference and use the lesser BCA regulations even though they are not permitted in Victoria. A large number of building 'professionals' also misunderstand how to understand the BCA references, making the installations even worse. I would love to know whether your roof drainage is compliant and whether the builder's plumber and surveyor have passed it as compliant. Crazyk ...however if I was a plumber there is a really quick sanity check. Min grade 1:100 Discharge capacity DN100 - 480l/m for approx 240m2 of catchment So if I have 330m2 I'm going to be in a bit of trouble. He said good point. The builder probably didn't know until you told him...after all...he is not a "qualified drainage engineer". A competent plumber should reference AS2200 when 'designing' a stormwater system...regardless of the Standard not being referenced in the contract. The DN 100mm pipe's performance will depend on the gradient and one other factor... The AS2200 figures are based on DN but the SN6 DWV 100mm pipe has an internal diameter (ID) of 104mm. A 100mm ID pipe has a volume of 7.854 litres per metre. A 104mm ID pipe has a volume of 8.495 litres per metre. This means that the 104mm ID pipe holds about 8% more volume. If you multiply 480 lpm x 1.08, we get an adjusted flow rate of 518 lpm but the pipe will also have less friction loss and so the adjusted flow rate is greater than 518 lpm. HOWEVER...your 330 sq m roof catchment discharge during a Melbourne 1:20 ARI (based on a 5 minute average rain intensity of 2.1666 mm per minute will be 330 x 2.1666 = 718 lpm. The QLD Govt. link below is now dated (2003) but it should interest you. http://www.statedevelopment.qld.gov.au/ ... er/136.pdf The following text is pasted from another thread where I also linked the QLD stormwater drainage document. Note that the AS2200 charts now indicate DN 100mm pipe as having a flow rate of 480 lpm with a 1:100 gradient, not the 450 lpm figures as shown in the QLD document that I used as my reference. Also note that the document calculates the roof area by using a multiplier based on the roof pitch to allow for wind driven rain, the formula used for determining gutter and downpipe sizes as per AS/NZS3500.3. They have also used this formula to determine the stormwater drainage pipe sizes. This is necessary where a number of downpipes drain into a single stormwater pipe on one side of the building as an allowance 'should' be made by a plumber for wind driven rain but the amount of rain falling on the total roof area is determined by the plan area, not the factored roof area that allows for wind driven rain on one side of the roof slope. You will understand after reading it why there are greater issues with DN 90mm pipes. The 100 mm uPVC SN6 DWV pipe has an internal volume (8.53 litres per metre) that is about 46% greater than the common use 90 mm uPVC stormwater pipe with 1.8 or 1.9 mm walls and an internal volume of 5.84 litres per metre. This is because the 90 mm stormwater pipe has an internal diameter (ID) of 86.2 mm whereas the much stronger (3 mm thick walls) 100 mm SN6 DWV pipe has an ID of 104.2 mm. AS2200 requires the nominal diameter 100 mm uPVC DWV pipe to have a maximum flow rate of 450 lpm (which is 0.88 metres per second) whereas the flimsy nominal diameter 90 mm uPVC stormwater pipe is mandated as 360 lpm (which is 1.03 metres per second). A bit strange one might say! When you do the calculations for pipes with a true 90 mm ID and a 100 mm ID, the respective internal volumes are 6.36 and 7.86 litres per metre.This in turn equates to respective flow rates of .94 and .95 metres per second when flowing at 360 and 450 litres per minute. Taking this further... If the 90 mm (86.2 ID) uPVC stormwater pipe was mandated for a maximum flow rate of .94 metres per second, the litres per minute flow rate would be 5.89 x .94 x 60 = 332 litres per minute, not 360! If the 100 mm (104.2 ID) uPVC SN6 DWV pipe was mandated for a maximum flow rate of .95 metres per second, the litres per minute flow rate would be 8.53 x .95 x 60 = 486 litres per minute, not 450! It is my opinion that the calculations for 90 mm ID and 100 mm ID uPVC pipe should not be transposed to nominal sized 90 mm uPVC stormwater pipe and 100 mm uPVC SN6 DWV pipe. The standards should, in my opinion, apply to the pipe's true ID and not their nominal ID, indicated as DN. The pipe's strength should also be taken into account. Farcical situations such as highlighted here where thin walled DN90 (actual ID is 86.2 mm) PVC stormwater pipe is understood to have a 17% higher velocity rating (1.03 metres per second) than the considerably stronger DN100 (actual ID is 104.2 mm) PVC DWV pipe (.88 metres per second) should never happen. 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: Hierarchy 14Oct 01, 2015 5:48 pm @SaveH2O yes I saw that QLD govt document which was instrumental in giving me basic foundation understanding of the stormwater system. It's a good learning guide but must be used in conjunction to all the other references made. My report to the builder based its structure on that and also on some empirical formulas to back up the general nature of that document. The one thing erroneously wrong with that, for Vic anyway, is the roof pitch factor. The AS is totally different and doesn't have a factor that big. Much smaller in fact. Re: Hierarchy 15Oct 01, 2015 7:04 pm Roof pitch factoring as per AS/NZS 3500.3 is the same for every State. The QLD document referenced AS/NZS 3500.3. If a stormwater drainage system is to be correctly designed, the designer has to have a credible reference to the pipe's flow rates over set gradients. AS2200 provides credible references regardless of whether the Standard is referenced. Plumbers shouldn't just make unknowledgeable guesses...but they do and they get away with it as a result of poorly written (and dumbed down) regulations. I would have asked the builder to see the hydraulic calculations and references used to design the system as they were either erroneous or non existent. 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: Hierarchy 18Oct 11, 2015 8:52 pm Great thread and lots of info. Out of interest why are those storm pipes so high? 'It's not the size of the dog in the fight, it's the size of the fight in the dog.' |