Browse Forums Building Standards; Getting It Right! Re: Protecting your Slab 541Apr 02, 2020 4:54 pm Clause 40 of the HIA contract requires Australian Standards to be followed. In this case AS 2870-2011 requires the builder to rectify the water pooling site defect. The clause in your contract you quoted refers to your responsibility to provide suitable drainage with landscaping after handover. It does not apply to the construction period when they are responsible for the drainage on your site. They cannot avoid their obligation to follow Australian Standards. Re: Protecting your Slab 542Jul 19, 2020 8:34 am Hi All,
This thread is full of useful information and I will be applying most of the things I learned here on my landscaping soon. I just need to get my head around some things to better communicate my plans to my suppliers. I basically want a concrete apron around the house. I need some advice on my planned drainage for my side access. I have two levels on our main side access. The higher level is 1.3m wide and the lower level is .9m wide - the difference in level heights is around 500mm. I have two stormwater pipes sticking out on the side access, one for each level and are around 450-500mm from my brick walls. My questions are the following: 1. My pest controller told me that the concrete needs to be below the bricks. But after reading on this forum, I've learned that it might probably need to be lower - the standard is 75mm below. I am just not clear if that is below the weep holes, damp proof sheet, or the other sheet I found slightly sticking out on the slab toe. In my photo below, I have highlighted yellow the damp proof sheet (I think), but what do you call the one highlighted in Green - is that the termite barrier of some sort? And where do I measure the 75mm from? I worry that the deeper they dig, the more danger it poses to my buried pipes. Should I ask for this to be dug by hand? Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 2. Regarding drains suitable for my situation. I am assuming I can just use a combination of channels drains and silt pits. My plan is to install channel drains at the edge of the concrete aprons (1300mm and 900mm wide) and install silt pits where the SW pipes stick out. My side access will have retaining walls near the boundary, so I'm not even sure if the channel drains would fit at the edge because the concrete sleeper posts auger holes are 400mm wide. Can I do away with just a silt pit for my 900mm wide section? I am not sure about the silt pit locations (highlighted below) either as they will be both halfway the width of my concrete aprons? Do I just need to slope around the area where the silt pits will be located instead of continuously sloping down to the channel drains? Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 3. How thick will the concrete be on the aprons? Do I need to specify other things as well like MPA, surface sealing, and joints seal (where my brick wall or slab meets the concrete)? Is the slope of 50mm on the first 1m formed during excavation or concreting? If on concreting, does this mean I need to specify around 100mm (or 75mm?) on the thinnest side of the concrete? 4. I'm just wondering if there any cheaper alternatives. Is there a readily-available durable plastic layer like PVC quality that can be laid above compacted roadbase and below some pebbles and stepping stones? Thanks in advance. Re: Protecting your Slab 543Jul 19, 2020 9:11 am Hi John, I can offer some assistance from experience having recently built but I’m sure others (such as Norfolk etc) will have more scientific references than I. The yellow line appears to be your termite barrier, granite guard if I’m correct. The green line is your initial brick/slab layer. The concrete apron needs to be 100mm thick if only foot traffic, and I personally would have the reinforcement bars drilled into your house slab to minimise apron movement/dropping. Always run the water away from the house. But I can see you are on top of that already. You may want to discuss whose responsibility for the retaining wall belongs to, as fencing is 50/50.if you are on a zero lot block your neighbours garage may crack and drop a few mm. Re: Protecting your Slab 544Jul 19, 2020 10:04 am The yellow line is the DPC. 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: Protecting your Slab 546Jul 19, 2020 12:30 pm GLO Hi John, I can offer some assistance from experience having recently built but I’m sure others (such as Norfolk etc) will have more scientific references than I. The yellow line appears to be your termite barrier, granite guard if I’m correct. The green line is your initial brick/slab layer. The concrete apron needs to be 100mm thick if only foot traffic, and I personally would have the reinforcement bars drilled into your house slab to minimise apron movement/dropping. Always run the water away from the house. But I can see you are on top of that already. You may want to discuss whose responsibility for the retaining wall belongs to, as fencing is 50/50.if you are on a zero lot block your neighbours garage may crack and drop a few mm. Thanks for the reply. Yes, must be the termite barrier. I really thought that the aprons shouldn’t be connected to the slab just in case any of them would move? Could you please clarify? I have sw pipes in the middle of the footpath. Not sure what’s the best option to do this. Do I slope to the the pit or slope to the edge? If I slope to the edge, I need a channel drain I think. The Zero lot garage will be Retained. The retaining wall will be 450mm offset from garage Re: Protecting your Slab 547Jul 19, 2020 2:36 pm Yes connected paths is best. Just make sure your concretor knows what he is doing and is licensed. Don't use some weekend warrior or someone's old mate. See screenshot from QBCC document https://www.qbcc.qld.gov.au/sites/defau ... 20Home.pdf Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Protecting your Slab 548Jul 19, 2020 2:44 pm sweetswisssteel Yes connected paths is best. Just make sure your concretor knows what he is doing and is licensed. Don't use some weekend warrior or someone's old mate. See screenshot from QBCC document https://www.qbcc.qld.gov.au/sites/defau ... 20Home.pdf Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Thank you for the very helpful information. I’m having a hard time looking for a reputable concreter in NSW. Each time I speak to them, they don’t Know around half Of what you are talking about. Where do I look really? My search continues. Re: Protecting your Slab 549Jul 19, 2020 2:52 pm Just make sure they are well regarded, are licenced etc. Maybe go to a few new housing estates and ask around or work your way through the master builders index of concretors. Say things like "I want my pathways dowelled into my slab". They might make more sense to the guys you are approaching. Cheers Re: Protecting your Slab 550Jul 19, 2020 3:24 pm John0322 SaveH2O The yellow line is the DPC. Thanks. Is this where I measure my 75mm to my concrete apron? Or is it from my termite barrier? Yes. The 75mm minimum gap applies to non permeable surfaces unless you are in a low rainfall intensity zone. The damp propf course is always at the bottom of the weep holes. 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: Protecting your Slab 551Jul 19, 2020 3:29 pm sweetswisssteel Yes connected paths is best. Just make sure your concretor knows what he is doing and is licensed. Don't use some weekend warrior or someone's old mate. See screenshot from QBCC document https://www.qbcc.qld.gov.au/sites/defau ... 20Home.pdf Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ . Re: Protecting your Slab 552Jul 19, 2020 3:52 pm Correct drainage of course. I have strip drains myself. The 75mm is negotiable if you have sufficient slope and drainage from the slab and good visual on the termite barrier. It's only an issue if you can't justify it. Common sense should always prevail. Re: Protecting your Slab 553Jul 19, 2020 4:17 pm SaveH2O John0322 SaveH2O The yellow line is the DPC. Thanks. Is this where I measure my 75mm to my concrete apron? Or is it from my termite barrier? Yes. The 75mm minimum gap applies to non permeable surfaces unless you are in a low rainfall intensity zone. The damp propf course is always at the bottom of the weep holes. Thank you. Does this mean though it’s okay to go above my termite barrier which sits below my dpc? Re: Protecting your Slab 554Jul 19, 2020 4:34 pm [quote="insider":2s27heh4][quote="sweetswisssteel":2s27heh4]Yes connected paths is best. Just make sure your concretor knows what he is doing and is licensed. Don't use some weekend warrior or someone's old mate. See screenshot from QBCC document https://www.qbcc.qld.gov.au/sites/defau ... 20Home.pdf[img:2s27heh4]https://uploads.tapatalk-cdn.com/20200719/8adfa55199cd9824a749caa381ce69a3.jpg[/img:2s27heh4] [/quote:2s27heh4] The only problem I have with this set up is that the water is dumped at the edge of the path which can cause the soil to wet up and heave therefore lifting the edge of concrete path and sloping it back towards the house. My preferred method is to have the spoon drain on the edge of the concrete path or have the path sloping towards storm water drain inlets spaced along the middle of the concrete path. I know this is not what the standards say but from my experience it is the most effective design to reduce the chances of excessive water reaching the foundations.[/quote:2s27heh4] Thanks. This might be applicable for me. Just to clarify, are you referring to something similar to below? Can I have a spoon drain just around 200mm wide? Personally, I prefer spoon drains as they are easier to maintain. I also haven’t figured out yet how I can concrete a drain adjacent to my retaining wall. I won’t be able to dig At the edge of the footpath as my wall auger holes are 400mm in diameter and concreted. Perhaps I can make the base of my retaining wall deeper so they level with the base of my spoon or channel drain? Adding another course of sleepers sounds expensive and might go beyond to what I have specified in the Engineering design I submitted for DA. [img:2s27heh4]https://imgur.com/gallery/Qcmn70L[/img:2s27heh4] Re: Protecting your Slab 555Jul 19, 2020 4:38 pm That would be your best option. Next time buy a better block haha. Cheers Re: Protecting your Slab 556Jul 22, 2020 1:51 pm Hi All, I have begun talking to concreters for the installation of my footpath. Most concreters told me that they don't excavate and they let the landscapers sort out the levels before they start. So I will be talking to my landscaper and I'm just trying to get my head around what to tell them. 1. First, is the grading done on soil or the concrete - please check illustrations below. And does it have to be compacted? Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 2. Second, will the following design work? And is it being done? Can I have a footpath with no slope away from the house and with ends that are higher so the water won't seep on the edges (see illustrations below)? I have a retaining wall on one side of the footpath. So alternately, can I just seal the space where the footpath meets my concrete sleepers? As for drainage, I'm planning to have two pit drains and channel drains running mid-width along the 22mm length of the footpath. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Protecting your Slab 557Jul 22, 2020 2:53 pm Engage a licenced structural landscaper and possibly a plumber first, work out all the finished levels that you will need for the concretor and then pour away. As long as the overall structure results in good drainage and adequate inspection etc then you can push it a bit on your 75mm. Ultimately you can also get the plan approved prior by a structural engineer. Cheers Thanks for the insights, that makes perfect sense, and yeah, I will be leaning on the experience of the excavator operator entirely. 6 16289 4 6231 The concreter will take and reuse. In my case I bought structural LVLs and scraped them back and used them as joists. 1 5215 |