Browse Forums Building A New House 1 Dec 20, 2022 1:30 pm Building a new home and had to get high front quad gutters (without slots) and 100mm downpipes to suit roof area and rainfall calcs from stormwater engineer. I queried overflow at the time (pre-contract) as our KDRB old home used to overflow into the eaves, then checked NCC which has the following solutions, with continuous methods required for the area and flow rates on our roof. Notwithstanding that NCC 2019 applies on our build. Understanding the NCC (abcb.gov.au) Overflow from eaves gutters (hia.com.au) Solution C is the best case. With solution B being next best but causes wavy gutters. This satisfied my query at the time and progressed, assuming they would install to suit the NCC Builders now haven't installed as such, and I've asked what they are going to do. Their suggestion was Solution D or E, both being insufficient with the areas and flow rates we have. We only have 2 end stops (solution D) and that would only allow 1L/s, not nearly enough using the calculator http://www.abcb.gov.au/Resources/Tools-Calculators/GDO-Calculator Using Solution E would require approximately 30 inverted nozzles across the gutters...roughly 1 every 2m. This would cause regular restrictions in flow with any debris in the gutters. I'm fairly set on them refitting the gutters with Solution C, even if it means some fascias visible at the low points. Other options I'm thinking are getting some inverted nozzles (maybe 10 instead of 30) and the end stop weirs then adding the gutter pumper system from saveH2O in the locations where the flow is highest. Would love some feedback or input on my ideas. Re: Gutter Overflow 2Dec 21, 2022 9:57 am I've been given this as a solution - provides for Solution B to be implemented lysaght-spacer-insert-flyer Re: Gutter Overflow 3Dec 21, 2022 10:37 am The example used in the HIA document is unrealistic because it cites a 12 metre x 10 metre roof draining to a 10 metre long gutter. They also haven't stated the roof slope and factored that slope for wind driven rain. What if that roof is an A frame roof? Regardless, you have a good understanding of the practicalities applicable to your own situation. All emergency overflow provisions discharge to atmosphere and factor all downpipes being totally blocked. You have a non compliance issue and have rightly identified the most suitable emergency overflow provision as being the 10mm gap at the back of the gutter. Are the water engineer's specifications/requirements referenced in the plans/contract? For what it's worth, numerous new houses are passed every year with non compliant roof drainage due to plumbers self certifying and the building surveyor accepting the plumber's certificate as proof of compliance. I feel that in this instance, the plumber and builder have been caught out by a knowledgeable client. The boot is on your foot and I would be insisting on the 10mm gap. Alternatively and because you have unslotted gutters which flow faster than slotted gutters, you could just accept what is there. Most gutters overflow away from the downpipes because builders fit downpipes to the end of walls (where the smaller roof areas are doh) but if the water flows faster to the downpipe, the downpipe will handle the higher flow. Re the inverted nozzle, the NCC states that it must have a minimum nozzle size of 100mm x 50mm, i.e. the base is larger as per the diagram. I would nor recommend fitting anything that large inside a gutter. The older inverted nozzles use to be 50mm round and not tapered or rarely tapered if any ever were. A vertical pipe's drainage capacity depends on the height of the water overflowing the weir wall and a 50mm pipe discharges water with heights above the nozzle of 20mm, 30mm, 40mm and 50mm at 0.74 l/s, 0.90 l/s, 1.04 l/s and 1.17 l/s respectively. These rates obviously did not meet the new discharge capacity requirement but all the regulators had to do was increase the 50mm pipe's discharge efficiency by requiring the nozzles to have an additional 3-4 10mm wide slots 10mm under the pipe's crest. Re the Gutter Pumper, it is a super cheap and effective solution that usually drains at 1 l/s withou't discharging excess water to atmosphere but because it is smaller than 100mm x 50mm, you will need a certified Performance Solution if you also require a certificate of compliance. 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: Gutter Overflow 4Dec 21, 2022 10:46 am jas25t I've been given this as a solution - provides for Solution B to be implemented lysaght-spacer-insert-flyer Note how Lysaght have factored the standard 22.5 degrees roof slope. It should be easier to retro fit than the one I have been trying to remember the name 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: Gutter Overflow 5Dec 21, 2022 11:10 am Thanks very much for your feedback. I have a decent understanding, most of which has come from reading your posts and information on your website! We have a 30deg roof, so flow velocities are even faster... Spacers are being installed and I'll look for other overflow opportunities at a later date. Likely a rain head solution as it has the largest outlet and flow. Re: Gutter Overflow 6Dec 21, 2022 1:09 pm A 30 degree roof area has a multiplier of 1.29 to factor wind driven rain. 100mm downpipes have a large drainage capacity. A 100mm vertical pipe with just 50mm of water above the crest will weir flow at 4.67 l/s and at 5.72 l/s with 75mm of water above the crest. I have played around with the idea of directing roof water towards the downpipe to increase flow velocity rather than have falling water communicate at 90 degrees with the water in the gutter, the biggest failing with roof drainage. The design was easily incorporated into a debris guard that performed three functions as the directional turbulence also cleaned the gutter, thereby also eliminating the biggest bugbear of standard leaf guards. It was easy to design but commercialisation is really the realm of a large company to take on. 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: Gutter Overflow 7Dec 21, 2022 3:13 pm SaveH2O A 30 degree roof area has a multiplier of 1.29 to factor wind driven rain. Yeah I also have a concern about the valleys not having the capacity for that reason SaveH2O 100mm downpipes have a large drainage capacity. A 100mm vertical pipe with just 50mm of water above the crest will weir flow at 4.67 l/s and at 5.72 l/s with 75mm of water above the crest. I'm satisfied that the gutters and downpipes have been appropriately sized and located for each roof drainage area (touching on the below comment) just not the overflow. SaveH2O I have played around with the idea of directing roof water towards the downpipe to increase flow velocity rather than have falling water communicate at 90 degrees with the water in the gutter, the biggest failing with roof drainage. The design was easily incorporated into a debris guard that performed three functions as the directional turbulence also cleaned the gutter, thereby also eliminating the biggest bugbear of standard leaf guards. It was easy to design but commercialisation is really the realm of a large company to take on. what a great idea. I'm interested in the design aspect, as surely providing any form of directing it would cause concentration of flow which I guess is the point, but would have an upper limit also at the point of change of direction? Re: Gutter Overflow 8Dec 21, 2022 5:11 pm The water goes through small surface effect part recessed ports that alter the direction of flow. I don't want to go into details even though I won't be commercialising it but the design method was a given. It is very simple. A friend invented the adhesion effect (most say surface tension) Leaf Safe Guttering system but he has retired and so has the business. It worked brilliantly, you can view the archived website by Googling the Way Back Machine and entering Leaf Safe Guttering. It didn't change the direction of the falling water but it did flush the gutter from the front to the back whereas most leaf guards retard flushing. It was a superior system. The most efficient gutters are the half round. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Much a do about nothing. You can see the fall heading to the actual drains. Stormwater ingress will be minimal and it's far better to have the top sitting flush rather… 12 6656 Thanks for that, the PVC pipe is still about 40cm below ground level and it sticks out of the sand with no end cap or anything on it just open pipe, is this the finished… 2 10875 No, I even have sections of narrowness where the tiles won't slide up any further. When I manage some spare time, I might play around with the first DIY part of my… 7 5300 |