How to fix loose paving slabs


If you’ve got an old patio then there is a good chance that you’ve got loose or wobbly paving slabs that can not only be irritating but also a real trip hazard, especially if your loose paving slabs are part of a step. Running a landscaping business, it’s not uncommon to be asked to repair wobbly slabs but the truth is that anyone can do it so I thought why not write a full guide on how to fix loose paving slabs yourself!

I’ve seen many customers try and fix their wobbly flagstones themselves with on the shelf products such as repair mortar as well as simply forcing sand and cement under each corner of the affected slabs hoping that it will fix the problem. And it might. For a while. But unless you are removing the old concrete and replacing it with new cement and not just painting a thin layer of repair mortar onto the bottom of the loose patio slab then it’s only ever going to be a temporary solution.

Which tools will I need to repair my loose paving slabs?

The only downside to repairing your patio yourself is that unless you are already a DIY person with tools to hand then you are going to need to buy some! Luckily, apart from the purchase of a small breaker or an SDS drill with the breaker option then the tools needed are relatively inexpensive! Although manually breaking the old concrete with nothing but a club hammer and bolster chisel is always an option! In short, the tools needed include;

  • Electric breaker (or club hammer and bolster chisel)
  • Dustpan & brush
  • Flexi tub
  • Trowel set
  • Rubber mallet

Aswell as the above, below is a list of the tools needed to repair your loose or wobbly paving slabs with a link which will take you straight to the Amazon website. As an Amazon affiliate partner I make a commission on any purchase made through a link on this website.

Using a breaker or SDS drill with the breaker option is the best tool for quickly and effectively removing the pointing around your loose paving slab and allowing you to lift it. Once lifted you will be able to use the breaker to remove any old concrete that once held the patio slab in place.

If your someone that doesn’t want to spend out on an an electric breaker that you will likely only use once then why not use a bolster chisel? Yes it’s more labour intensive but if you’ve only got the odd slab to repair here and there then it could be worth saving some money. But don’t forget your club hammer!

This may seem a little obvious to some but your going to need to sweep up all that old concrete that you’ve now chisseled away. A dustpan and brush should do nicely.

A flexi tub or gorilla tub is my favourite way of mixing sand and cement for those smaller jobs such as fixing loose paving slabs since they are just so easy to clean afterwards and don’t crack and break like your standard plastic bucket!

From mixing your sand and cement to laying it for your paving slabs your going to need a trowel. I like to use a plastering trowel but here is a full set so that you can find what works best for you!

A rubber mallet may be cheap but it’s the only way to safely tap down your loose patio slab without breaking it!

Which materials will I need to fix my loose patio slabs?

I like a nice and simple heading to write about – This one’s easy! All you need is some building sand and cement. Oh and some jointing compound! But if you’ve only got the odd loose paving slab to repair then you can use your sand and cement to point with.

How to repair loose or wobbly patio slabs

There’s only 1 way to properly fix loose patio slabs and that is to undo all of the work that went into laying them in the first place and starting again. Don’t worry though, the whole process is relatively simple and shouldn’t take too long to accomplish. Just follow the below steps!

  1. Start by removing any old jointing (the cement that sits between the paving slabs). You can do this by using a bolster chisel and hammer or an electric breaker if you have one.
  2. Next you are going to need to carefully lift your patio slab and put it to one side. I use a spade to initially help lift it.
  3. Now it’s time for the most labour intensive part which is to remove the concrete that your loose patio slab once sat on. Again, it’s easier to use a small, handheld electric breaker but a bolster chisel and club hammer will do the job too.
  4. With the old concrete removed it’s time to mix some sand and cement. When laying a new patio I usually mix 5 part sharp sand to 1 part cement (5:1) but when it comes to fixing the odd loose paving slab I use building sand instead of sharp sand due to it being more ‘sticky’. I use a wet mix, much like the mortar you’d see when laying bricks and mix to a ratio of 3 to 1 (3:1).
  5. Using the surrounding paving slabs as a guide to how much mortar needs to be layed, start by shoveling the mortar into the area that’s to be paved. I use a plastering trowel to smooth the area and try to have it sit just above the bottom of the surround patio slabs.
  6. All you need to do now is place your paving slab onto the mortar. If done correctly, your slab should sit just above the surrounding slabs which will allow you to tap it down with a rubber mallet until flush with the rest of your patio. If your paving slab won’t tap down enough then you will need to remove some of the mortar. Making a hole in the centre can also help as it gives somewhere for the mortar to move to when tapping your slab down.
  7. Finally, all you need to do to finish repairing your loose or wobbly paving slabs is to point (also known as jointing) around it. You can do this 1 of 2 ways. The first is to use your ready mixed mortar and a pointing trowel to carefully push the cement into the gap around/in-between the surrounding slabs. Be careful not to use too wet of a mix as it’s easy to stain the paving and always have a damp sponge ready to wipe off any cement from the edges of the slabs. The alternative method is to purchase a tub of jointing compound which uses a stainless resin and comes in a variety of colours. Many of these jointing compounds are as easy as wetting the paved area, sweeping it in and walking away.

My thoughts on how to fix loose paving slabs

Repairing wobbly patio slabs really isn’t that hard and any DIY or hands on person will be able to do it. I’m a professional that gets paid to fix loose paving slabs and here I am telling you to do it yourselves! I would expect each loose or wobbly slab to take no longer than an hour to fix from start to finish and will cost no more than a few pounds in materials either. If however you do get stuck or have any questions before you get started then please do comment below as I am always keen to help!

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