How to lift, relay, and repair sunken block paving

Time needed: 4 hours.

1. Determine which area of the block paving needs refurbishment

   Sunken block pavings are relatively easy to identify, especially when it’s raining, and puddles start to form in the low spots. It’s important to note that choosing to remove a few extra blocks from around the actual sunken spot, makes the process of screeding the bedding layer easier. 
   

2. Lift and remove the uneven blocks

   The fastest and easiest way to remove a block is by using the aptly-named block extractor tool, also known as a block grab. It works by inserting blades into the joints on either side of the block, and then, using the handles in a scissoring motion, you can grab and wiggle it loose from the rest of the pavement. From then on it’s easy to remove the other uneven blocks and, ideally, a couple around them as well. This will help you to level out the bed afterwards.
   
   If you don’t have a block extractor tool, you can use trowels, chisels, and your strength to remove the first block. This is usually the more difficult way to do it, so be patient and persistent.
   

3. Clean the lifted block paving 

   Once removed, the blocks will have jointing and bedding sand on the edges and the base. Make sure to clean them from all remaining sand, using the blade of a trowel and a soft hand brush. This is vital, otherwise the sand will disrupt the proper relaying of the pavement. Cleaning the blocks ensures that they are tight against the other blocks, levelled with the new laying course, and even with the paving pattern.

4. Level up the uneven bed 

   Next, you need to remove the existing bed, and replace it with fresh bedding material. This is optional, but still highly recommended, because over time and due to traffic, the grit sand becomes crushed and thus the grading won’t be as good. If the laying course has silt or an organic material on it, then the best option is to replace it entirely in the area of the repair. The sand might be compacted or even solid, making it difficult to remove. You can use a brick hammer to break it up and aid the process. Keep in mind that the sub-base shouldn’t be removed unless the settlement is more than 20mm deep. 
   
   Once you have removed the old bedding material, pour the fresh grit sand, and use a float or a trowel to level it out. Always use grit sand instead of building sand, since the former provides better drainage, ensuring better support for your pavement, whereas the latter will just get soggy. Use the original sand bed in the outer area, where the blocks were not sunken, as reference for evening the bed on which the blocks will be laid. Some believe that the area should be leveled out 3mm to 5mm higher than that, which will be evened out in the following weeks of usage. Experts, however, advise that this is only suitable for public areas, where the traffic is greater than what you would expect for a private driveway.
   
   Before proceeding to the next step, make sure that the bed is leveled out at each point by placing a block in different areas and checking it against a straightedge rested upon the blocks surrounding the gaps.
   

5. Re-laying the patio

   Once you have evened out the new bed, it’s time to put back the blocks. If some of the blocks are cut, then start with the ones that are full, working your way to the cut pieces. To achieve the best results, leave no more than 2-5mm of space between the blocks. You can use a rubber mallet to assist squeezing blocks into tight spaces.
   
   Sometimes when a sunken block paving area that includes cut pieces is re-laid, the blocks do not fit as well. This happens because over time blocks shift slightly under the weight of the traffic, thus opening up the joints. If that is the case with your block paving, it’s a good idea to cut new pieces to ensure a tight pavement.
   

6. Final touches with jointing sand

   When you have re-laid your blocks, sweep the area to remove any debris, such as small stones, which might get stuck between the joints. To consolidate the blocks, use a rubber mallet, and give them a few bangs. If you have repaired a larger sunken block paving area, perhaps a more time-effective option would be to use a vibrating plate compactor to consolidate the pavement. 
   
   Next, the area needs to be re-jointed using kiln dried sand. Make sure that the blocks are dry before starting the process in order to allow the sand to flow freely into the joints. Pour your kiln dried sand generously over the repaired block paving area, allowing it to fill up the joints. Then, sweep the excess dry sand to the side, and use the rubber mallet, or the vibrating plate contractor, to lock the blocks and the sand into place. If you see that some of the joints are low on sand, sweep the sand on the side into them. 
   
   Et voila! Now you have successfully refurbished your sunken block paving!