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Hi Bunnings community members.
I'm looking to concrete a 16sqm area for future carport build.The previous owner put gravel for aesthetic purpose but get slippery and cause trip hazard.
I've removed most gravel myself.
To get the area concreted 100m depth with steel mesh, how much would I expect to pay a professional?
I'm based in Sydney.
Many thanks
Hello @southpolemonkey
Thank you very much for sharing your question about laying a concrete base for your future carport.
Although it may seem like it is an easy process of digging into the ground, building formwork and putting reo into the ground. There are some very important things that must be taken into consideration before the concrete is poured into place.
Any mistakes made in weight bearing calculation, foundation preparation, drainage and drying process will cause your slab to crack and buckle. Because you are laying down such a large surface, I don't recommend it as a D.I.Y. project. I suggest engaging the services of a Professional Concrete Driveway contractor. They will have the experience and knowledge to build it correctly and make it last.
Each contractor will have their own way of quoting your project. Some will insist that they build the formwork for you so that it will have the proper fall. Others will want to use only certain types of materials for the assembly. I suggest doing a quick search online and getting several quotes for the area in question. I strongly suggest putting in Everhard 3m EasyDRAIN Polymer Grate And Prejoined Channel. It will divert any water that might fall away from the slab and prevent it from washing the soil underneath.
The most critical part aside from all that I've mentioned is access for the cement truck. If the truck can't back up into your driveway or it seems like your current driveway is not able to accommodate the weight of the concrete truck. A concrete pump will need to be added to your quote.
It's much better to get a quote as you will see exactly what you are paying for rather than just getting a dollar figure for a square meter of concrete.
Let me call on our experienced members @Dave-1 and @diy_hausdesigns for their recommendations.
If you need further assistance, please let us know.
Eric
Good afternoon @southpolemonkey
Now thats an interesting looking driveway you are adding to 
My way of thinking is definently along the lines of @EricL's suggestion.
I can see a drain that terminates or is burried under the gravel sectioon at the back, do you know where the water falls to?
Something to consider is the drainage of water from the retaining wall. If you concrete all that pebbled area that may stop some of the subsurface water traveling across under the ground. It kind of looks like the water drains from the pebbels toward sthe existing yellow concrete? Id suggest to have a look at some of the metal sheds and their recomendations for the depth of concrete to bolt to (Just to kind of factor in future proofing the slab even if you dont intend to put a structure over it)
I just had a google at the Australian standards recomended for a garage area and its seems to be somewhere between 100mm - 150mm. It makes me think that a professional will know a lot more about weight bearing and factor in the right jhand side of your new area that looks like it drops away?
I really like the style of your retaining wall by the way And does it have any cracking or settling in it?
Dave
The existed grate drainage isn't going anywhere. I guess the original thinking was to collect water from high side (retaining wall, pebble area). But it didn't turns out great, pebble and leaves block it and has been crushed by car tyres several times.
It's a tricky spot indeed. The pebble area is 5.4m and 4.5m by length, and 3m by width. To put a standard single carport on it, two posts would need to sit on existed concrete slope.
I got a quote for $3300 including excavation (without rubbish removal), framework and pour 100mm 32mpa concrete. Sounds a bit high to me, but I guess this is not a big job so they charge high per sqm.
@Dave-1the previous owner did the hard work to build the sandstone retaining wall. Some capstone are loosen and I need to repoint sometime.
Afternoon @southpolemonkey
Ouch to the drain being crushed 😕
$3300 for that sized area actually sound slow to me and thats just from workmates referencing work that they have had done without anything specific.
Does it include reo in the concrete?
One thing to note and possibly why your drainage dosnt work is that yellow part of the concrete and its patchwork of holes (I thought it was decorative) looks kind of like someone has been hunting pipes and repairing them underneath that slab...
Good news is that the driveway dosnt look too long so a concrete truck could potentially stay on the road and use their chanel to move it across so you dont chance cracking that yellow concrete
Dave
Thanks @Dave-1
Good to hear your opinion about the quote.
Are you referring to the sandstone paver? I think they are for aesthetic purpose.
One thing I'm still uncertain is how to install post anchors on the slope yellow concrete. I'm thinking use a angle grinder to cut a square, dig a hole and fill in with new concrete, that should sit the anchors.
Would love to hear some thoughts.
Afternoon @southpolemonkey
yeah those decorative pavers? I thought they were cut out sections of the yellow concrete that had been filled in (love figuring out how something was done and then asking why )
Post Anchors - Id probarly try and drill in an unseen spot to judge the depth to start with, just to see how thick the concrete is. Then would drill the holes for the bolts for the posts in at the angle to keep the post verticaly, put in the bolts and have them standing straight up. Even if the area is slopped this should work. The idea would be to put in 4 bolts or 2 and then you put a nut and washer half way down and the same the other side, keep the post vertical and then add washers then nuts to tighen it down so the post is verticle but the ground will be angled . You then concrete around it in a square so it looks like a plinth. (one side will be taller then the otherside) You shouldnt need to cut a section out of the concrete this way.
Dave
Before you begin, I suggest checking your local council's rules and regulations regarding building a carport. Because it is a large weight bearing structure, I suggest engaging the services of an engineer or drafts person. They will be aware of the rules when drawing the plans for your carport. In this manner should the council require a plan, you will have one ready.
In order to lower your quote for the driveway, I suggest doing all the heavy lifting. That includes removing all the gravel and digging down to the required depth requested by the driveway contractor. You can also purchase your own materials for the formwork and drainage and all the specialist has to do is to assemble it.
My only other suggestion is to inform the driveway contractor of your plans to install a carport.
If you need further assistance, please let us know.
Eric
Morning @southpolemonkey
I was picking up a coffee and spotted what I was trying to describe Here is what I mean by the bolts poking out of the concrete and then the nuts on the underside can be adjusted to make the post vertical. This way a sloped slab can still have vertical posts on it.
I was going to get down and take a shot underneath but too many people were about
Dave
Morning @Dave-1
Interesting technique, would it work for a big fall say 100mm?
I noticed the other day of how thing was done in a local park. Looks like the same technique you've described.
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