Child Item

How much to lay concrete base for carport?

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

Find more posts tagged with

Tools and Materials

Building and Construction

Accepted answers

All comments

EricL

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

Dave-1

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

southpolemonkey

Thanks @EricL and @Dave-1

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.

Dave-1

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

southpolemonkey

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.

Dave-1

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

EricL

Hi @southpolemonkey

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

Dave-1

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

southpolemonkey

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.

Dave-1

@southpolemonkey

hahahahah Thats a nicer looking post! And 100mm fall may be more then I would use safely. Thats a pretty steep fall in a short distance. Are you talking about an overall fall over say 3m or over a smaller distance?

If you are thinking of doing something like that then it would be wise to look into the tensile strength of the bolts (Ive had a google at the info but always feel odd at posting outside sites in here 🙂 ) There is a maximum distance unsupported, Even with the concrete formed around it later on. I am starting to think due to your requirments (steepness/slope on the bottom side) it may be an idea to hit up a builder or talk to the fence/carport people you are purchasing from. That way you will have accurate advice for the product itself.

I have a sloping driveway and you have given me thought on how I would do it myself... Mmm I think Id go for an oversized span so the posts will go into new concrete bases that will be level and specific for the carport rather then try and either cut or level by the way I suggested) If you take a look at my profile you will see a few shots of the driveway and it looks steeper or the same as yours.

Dave

southpolemonkey

@Dave-1

The pebble area is not big enough unfortunately (4.5m in length on shorted side), so the post will sit into the existed concrete.

Found an image similar to what I'm thinking.

Dave-1

Afternoon @southpolemonkey

How about something like this, The blue is for new concrete footings and the red for the supports. It will stretch over and outside the parking area to give more space for the car?

Dave

Child Item