How to fix cracked concrete patio?

Question

Got a coloured concrete patio that has some cracks and unevenness. The slope towards the drain also isn't perfect, some pooling on rainy days, though it isn't too bad. Possibly soil movement has caused it, nothing severe but enough that I can't really enjoy the space as is.

Trying to figure out the cheapest realistic DIY path. Two ways I'm thinking:

Option 1: Leave the concrete in place and build over it. Patch it up and level things out, then either pour something like concrete, an outdoor resurfacer, or an overlay on top, or lay pavers/tiles straight over the existing slab. Need to know how to prep the current concrete for another layer on top, and how to sort levels and slope properly.

Option 2: Rip the whole thing out and start again. Assuming this costs more/more work so not my first preference, but keen to know what it actually involves if it comes to that.

What I actually want to know: what's realistic here given the condition, what's the actual process for each option start to finish, what tools and materials would I need, and if anyone's got good YouTube videos or guides showing the real process (not just a before/after), that'd be great.

EricL · Answer

Hello @TheIndianBunny

Thank you for sharing your questions about your concrete patio. The difficulty of breaking up the concrete patio will depend on its thickness and size. If the patio is over six meters long, two meters wide and over 100mm thick, it will be a challenging demolition. You'll need an electric or air powered concrete breaker to demolish the concrete base. It will also be necessary to hire a skip to get rid of the debris. As to the level of the soil, it will get addressed when redoing the base prep as you mentioned.

Your list of steps such as breaking up the slab, base prep, getting the drainage slope and levels right are spot on. You don't need anything too special when it comes to tools except maybe the concrete breaker. Since you'll be replacing it with pavers and pebbles, basic garden tools would be handy, a shovel, builders line for creating guides and a spirit level to make sure your base is slopping in the right direction.

I suggest having a look at these guides - How To Lay a Base For Pavers and How To Lay Pavers. These guides will give you a very good idea of the tools and equipment you'll need to prepare the soil base and laying of the pavers. I've placed a sample image using AI to give you an idea of what it could look like. If you can provide a full photo of the patio entrance area, we can provide a better render for you.

If you need further assistance, please let us know.

Eric

TheIndianBunny · Answer

Hi Mitchell,

Thanks so much for the detailed response, really useful. Cracks have grown wider in recent months and the movement seems ongoing, and water's probably been seeping in through them too, so I want to get this sorted soon.

Your response lines up with what I was already thinking, that the slab needs to go. I've decided not to replace it with concrete and am instead thinking of a mix of pavers/outdoor tiles and some use of pebbles. I'm comfortable with tools and would call my DIY skills average to good, so the two big questions are: First, is this a realistic DIY project for someone at my level doing it solo? And second, since the soil movement has been ongoing, does it need a pair of professional eyes on it, or is that something that gets fixed as part of redoing the base prep anyway?

Worth mentioning, there are no trees nearby and the cracks are limited to the patio and maybe a couple of mtrs around it. So my guess is it's mostly weather and water damage over time since it's old.

Lastly, if I do take this on, what's the actual process involved and materials required like breaking up the slab, base prep, getting the drainage slope and levels right, and what tools would I need for all that?

Appreciate all the help so far.

-TheIndianBunny

MitchellMc · Answer

Welcome to the Bunnings Workshop community @TheIndianBunny. It's terrific to have you join us and many thanks for your question on concrete cracks.

Looking at your photos, there are several structural cracks running through the slab, which suggests there has been some movement in either the slab itself or the ground beneath it. Because of that, I'd rule out virtually any coating, resurfacer or tiles bonded directly to the existing concrete. While they might look good initially, the underlying movement is likely to cause them to crack as well.

If you wanted to leave the slab in place, I'd be looking at floating finishes rather than bonded ones. One option is to use deck tiles, which can simply be laid over the existing surface to dramatically improve the appearance while disguising the cracks underneath.

Laying pavers over the existing slab is another possibility, provided you can accommodate the additional height and maintain suitable drainage away from the house.

If you decide the slab really needs to be replaced, the process would generally involve:

* Breaking up and removing the existing slab.
* Investigating and rectifying the cause of the movement if required.
* Preparing and compacting a new base.
* Installing formwork and reinforcement.
* Pouring and finishing a new slab with the correct falls towards the drain.

It's certainly the more expensive option, but it gives you the best long-term result if the existing slab is continuing to move.

Given you've mentioned some unevenness and ponding, I'd also be trying to determine whether the movement has stabilised or is ongoing before committing to any new surface finish.

Have the cracks changed noticeably over time, or have they looked much the same since you first noticed them? That will help determine whether the movement is likely to be ongoing.

Please let me know if you have any questions.

Mitchell