Browse Forums Building Standards; Getting It Right! 1 Nov 01, 2016 8:44 pm Hi all As you will have seen already on this forum this topic has been beaten with a stick over and over again. I draw your attention to rule 3.1.2.3 of the NCC Volume 2 which states: Surface water must be diverted away from Class 1 buildings as follows: (a) Slab-on-ground — finished ground level adjacent to buildings: the external finished surface surrounding the slab must be drained to move surface water away from the building and graded to give a slope of not less than (see Figure 3.1.2.2)— (i) 25 mm over the first 1 m from the building in low rainfall intensity areas for surfaces that are reasonably impermeable (such as concrete or clay paving); or (ii) 50 mm over the first 1 m from the building in any other case. However, in the explanatory notes, the following is stated: The appropriate slab height above finished ground level and the slope of the external finished surface surrounding the slab may vary depending on: 1. The local plumbing requirements; in particular the height of the overflow relief gully relative to drainage fittings and ground level (to work effectively they must be a minimum of 150 mm below the lowest sanitary fixture). 2. The run-off from storms, particularly in areas of high rainfall intensity, and the local topography. 3. The effect of excavation on a cut and fill site. 4. The possibility of flooding. 5. Termite risk management provisions. Does this mean that the rule is subject to the discretion of certifying authorities? I only have 1 metre on each side of my house available and I would not like to slope the concrete pathway 50mm from the edge of the home to the boundary. I am happy to place ample stormwater run-off channel drainage along the pathway. Keen to hear your thoughts and experiences/expertise. Cheers Shanil Re: NCC Volume 2 Rule 3.1.2.3 2Nov 04, 2016 12:08 am The way that I have always read it is that 3.1.2.3 is the minimum and that the slope can vary greater than the minimum if deemed appropriate. The slab's footprint and the surrounding topography should be factored when the site cut and slab is engineered but this is not always done to satisfaction. trooper56 I only have 1 metre on each side of my house available and I would not like to slope the concrete pathway 50mm from the edge of the home to the boundary. The builder is required to have the ground sloped away from the slab during construction. If the builder has adhered to his regulatory requirements, then the concrete perimeter will have a base that is already sloped. If you don't have the minimum slope and there is a problem with the slab later on, you have effectively given the builder a get out of jail free card. 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: NCC Volume 2 Rule 3.1.2.3 3Nov 04, 2016 9:56 pm Thanks H2O...my point was effectively getting at running a 0 slope pathway on the sides of the home 1 metre wide and placing channels drains along the side between the concrete pathway and the brickwork/top of slab. Was wondering whether the explanatory memorandum coveted instances like this. Cheers Re: NCC Volume 2 Rule 3.1.2.3 4Nov 05, 2016 2:02 am Hmmm? Are you a dual account holder? The BCA is often ambiguous and poorly written in part but my belief is that the minimum requirement cannot be overridden and that the explanatory information only refers to variances greater than the minimum that may be deemed appropriate under certain circumstances as per the examples given. That said, it is your property and you can do whatever you like and there have been numerous examples in this forum of non compliant concreting that was done both without the owner being the wiser and also at the owner's instruction. It would not be hard to find a concreter to do what you want but I would not do anything to void any warranties and having a concrete path with no slope and also "placing channels drains along the side between the concrete pathway and the brickwork/top of slab" would do so. What is your soil classification and location? If the builder had proper site drainage during construction, the house would have been handed over with the correct slope away from the slab. 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: NCC Volume 2 Rule 3.1.2.3 5Nov 05, 2016 7:22 am Thanks H2O...H1 slab so clay/reactive soil. I am just concerned that the PCA will not issue the occupation certificate if the pathway does not slope away correctly but I see so many homes on here in breach of the BCA but have occupation certificates issued Re: NCC Volume 2 Rule 3.1.2.3 7Nov 05, 2016 11:16 am Building surveyors miss many things and a lot of non compliance passes through but given that you are on reactive soil, I would not even second think about doing what you are considering. A 1:20 slope (50mm in 1 metre) is not steep, just get a one metre flat straight edge and lay it across a flat surface and you will see. You are in NSW but here in Victoria, the Victorian Building Authority (VBA) recommends using a 70mm (1:14.3) slope over the first metre. The fact that this is not regulated and not stated as such is an annoying oversight but that is another story. See link below. http://www.vba.vic.gov.au/__data/assets ... _FINAL.pdf I read through your old posts to try to find out where you are building and I came across your post about your builder unlawfully refusing your building consultant entry to do a final inspection. I would not be giving your builder any free tickets but it also sounds like you haven't used a building consultant for stage inspections. This is a worry if you haven't, the final inspection is far from being the most important stage inspection. viewtopic.php?f=31&t=85475&p=1633756#p1633756 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: NCC Volume 2 Rule 3.1.2.3 9Nov 05, 2016 1:35 pm An ag pipe cannot connect direct to the stormwater, there has to be a silt pit close to the stormwater junction. You need to check as to whether 100mm would allow you to do this. 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: NCC Volume 2 Rule 3.1.2.3 10Nov 05, 2016 7:50 pm Hmmm doesn't look like I'll get to do that...my weep holes and DPC are quite high I checked today which allows me to start to concrete a bit higher than the exposed Slab...maybe one brick higher than I wanted which will still give me >75mm clearance from the DPC and >150mm from the internal floors. Let's me slope as required without finishing below the base of the colourbond fence. Re: NCC Volume 2 Rule 3.1.2.3 12Nov 05, 2016 10:23 pm Are you planning on doing the concreting yourself? You seem to know more about the regulations than many concreters. It also appears that your slab and site cut was designed and laid with the appropriate heights which is not always the case. shanil86 Do you think some ableflex should be used between the building and the concrete pathway?? Absolutely. https://www.cornellengineers.com.au/all-about-abelflex/ 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: NCC Volume 2 Rule 3.1.2.3 14Aug 08, 2022 7:24 am [quote="SaveH2O"]The way that I have always read it is that 3.1.2.3 is the minimum and that the slope can vary greater than the minimum if deemed appropriate. The slab's footprint and the surrounding topography should be factored when the site cut and slab is engineered but this is not always done to satisfaction. Hi there, I have been reading through the BCA guidelines and I haven’t been able to confirm the required angle for an outdoor area on the ground floor slab that is covered by the 1st floor slab. The two sliding doors out to this area have built in drains so there will be no step, however I’d like to confirm if I still need a 50 or 100mm fall in the first metre of the covered area if this area is 5 metres deep or is it within the last metre closest to the edge? Thank you in advance!!!! Re: NCC Volume 2 Rule 3.1.2.3 15Aug 08, 2022 1:59 pm You could always commission alternative solution if you have trouble getting OC Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: NCC Volume 2 Rule 3.1.2.3 16Aug 12, 2022 5:35 pm trooper56 Hi all As you will have seen already on this forum this topic has been beaten with a stick over and over again. I draw your attention to rule 3.1.2.3 of the NCC Volume 2 which states: Surface water must be diverted away from Class 1 buildings as follows: (a) Slab-on-ground — finished ground level adjacent to buildings: the external finished surface surrounding the slab must be drained to move surface water away from the building and graded to give a slope of not less than (see Figure 3.1.2.2)— (i) 25 mm over the first 1 m from the building in low rainfall intensity areas for surfaces that are reasonably impermeable (such as concrete or clay paving); or (ii) 50 mm over the first 1 m from the building in any other case. However, in the explanatory notes, the following is stated: The appropriate slab height above finished ground level and the slope of the external finished surface surrounding the slab may vary depending on: 1. The local plumbing requirements; in particular the height of the overflow relief gully relative to drainage fittings and ground level (to work effectively they must be a minimum of 150 mm below the lowest sanitary fixture). 2. The run-off from storms, particularly in areas of high rainfall intensity, and the local topography. 3. The effect of excavation on a cut and fill site. 4. The possibility of flooding. 5. Termite risk management provisions. Does this mean that the rule is subject to the discretion of certifying authorities? I only have 1 metre on each side of my house available and I would not like to slope the concrete pathway 50mm from the edge of the home to the boundary. I am happy to place ample stormwater run-off channel drainage along the pathway. Keen to hear your thoughts and experiences/expertise. Cheers Shanil I Think what you are proposing is better than the standards as long as the plumbing is done by a professional and can cope with a heavy downfall. Just sloping the concrete away from the house either dumps it on the ground next to your paving or dumps it on your neighbour both can have consequences. thanks guys! yes this is how I've exactly raised it with the builder. still awaiting response. 12 6280 Whats in the gap between the fence and the concrete? I assume dirt/plants etc, right? like youve shown in other parts of the pics. Im not sure how familiar you are with… 8 6177 10 years ago was a different software than we use now. it has had a lot of changes over the past years. Improvments to the software and changes to how Nathers models need… 8 2256 |