Yes, you should always remove weeds before sealing block paving. Applying a sealer over existing weeds or moss can trap the problem underneath and prevent you from getting the clean, tidy finish you are looking for.
Here at Swiss Seal, we often get asked whether sealing a driveway will simply deal with weeds. Unfortunately, it is not quite that straightforward. A good block paving sealer can help with weed prevention, but the paving needs to be properly prepared first.
Why do weeds need removing before sealing?
Weeds growing between paving blocks need to be removed before you start the sealing process. This is because their roots and organic matter can remain down in the joints, even if the visible growth has been pulled away.
If you seal the surface without properly dealing with the weeds, you can end up trapping moisture and debris in the joints. New growth may then appear through the sealed surface, leaving you back where you started.
For the best results, block paving weed removal should be part of your preparation rather than something you tackle after sealing.
How should you remove weeds from block paving?
Start by removing as much visible weed growth as possible, including the roots where you can. A stiff brush can be useful for clearing smaller weeds and loose material from the joints.
It is also important to remove moss, algae, dirt and other organic debris. If the paving is particularly dirty, give it a thorough clean and allow plenty of time for the surface to dry completely.
The joints should be checked too. If they have become damaged or washed out, they may need topping up with suitable kiln-dried jointing sand before sealing.
Can sealing block paving help prevent weeds?
Yes, a suitable block paving sealer can help reduce future weed growth, but it cannot replace proper preparation.
Once the paving has been cleaned and the joints are in good condition, sealing helps protect the surface and can make it more difficult for moisture and dirt to penetrate.
A sealed driveway is also generally easier to keep clean, which can help reduce the conditions that encourage unwanted growth.
However, no sealer should be considered a guaranteed weed-proof solution. We always recommend dealing with existing weeds first and making sure the paving is properly prepared before applying any product.
How long should you wait before sealing?
The paving needs to be properly dry before sealing. This is particularly important after cleaning, as moisture can remain within the joints and underneath the blocks.
Don't be tempted to rush the job because the surface looks dry on top. Give it sufficient time to dry out, particularly in the cooler or damper conditions we often get here in the UK.
Good preparation is what makes a sealing job last. Remove the weeds, clean the paving thoroughly, check the joints and allow everything to dry before applying your block paving sealer. Taking the extra time at this stage can make a noticeable difference to the finished result.