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Interlocking concrete pavement surfaces are not free from maintenance. They hold many benefits over alternative pavement options, but if not designed appropriately they may require more maintenance. Moss growth in between pavers may be a sign of poor drainage or just a project that was constructed in an area with minimal sunlight or lots of moisture present. It could also be a sign that you should be turning your sprinkler system off around your project to reduce the amount of water that is going to come in contact with it. Moss will grow in areas with lots of moisture and minimal sunlight. However, moss growth to all is not a negative thing. In some cases, you may want to embrace the moss growth. This may be the case in a natural stone patio. Regardless, here is what you should do to remove moss from your paver surface and how you can prevent moss growth in the future.
Removing Moss from Pavers
Moss will grow in damp places that does not see a lot of sunlight. The best way to deal with moss growth is to prevent it in the design process of the project. However, if you are reading this then perhaps we are past that option and we are looking at ways in which we can remove that moss growth from your pavers. More than likely the moss is first growing in the joints of your paving stones. This is because the joints represent the lowest point in the surface of the project where water will sit the longest. It is this moisture that the moss will begin to grow and spread from the joints possibly onto the pavers themselves.
There are natural options in order to remove moss including using baking soda, vinegar, or boiling water much like you would to kill weed growth. When it comes to using baking soda or vinegar, you will want to experiment on a small part of the project that is least visible and only try to use it on the moss growth. You will want to let it sit and continue to apply during a time period if it shows that it is working to kill moss on pavers However, you are going to want to keep an eye on the pavers themselves and ensuring that it is not discoloring them. It is important to test this to see if it works before moving onto a larger area so that you do not discolor the entire project. This will take much longer to accomplish, but it ensures that you do not destroy your project. Give the test period a week of consistent application before you move on to a larger area and continue to scale up until the entire project is completed. It may be beneficial to contact the manufacturer of the paver to inquire on applying vinegar or baking soda to their product.
That being said, this is not our preferred method of removing moss.
Preferred Process of Moss Removal from Pavers
If you have moss growing in the joints of your pavers, it may be time to replace the jointing compound as well. If this is what you want to continue with, you can opt to use a pressure washer in order to clean the entire surface of the pavers and to get rid of the moss between the pavers as well. Ideally in this process you would have a hot water pressure washer to speed up the process, but we have been able to use a regular pressure washer with around 2,500 PSI to accomplish this.
When pressure washing the moss from the joints of your pavers, you will want to use the turbo nozzle attachment to the pressure washer that oscillates the water. This is important so that the water is not concentrated in one area for too long as this could destroy the pavers. You will work from the top of the slope and work your way down. It is much easier if you focus on doing a good job in one pass. If you have to opt for a second pass, any dirt or material will be blown into the empty joints as you pressure wash through the entire project.
You cannot pressure wash the joints of your project without having to replace the jointing compound. This is only an option if you know you are going to opt to replace the joint material throughout your project. Though if you are only struggling in a small portion of your project, you could also use a tool to remove moss between pavers. This is a basic sod knife or hook knife that will scrape the joints and remove any growth out of the joints. It works well, but is more labor intensive of a process to remove the moss growth.
If you are experiencing further growth beyond moss, you will want to be careful dedicating your time and labor to going through this process. If weed growth has overtaken your patio, pressure washing will not remove the weeds. You will see that some are removed, but you may push some of the weeds into the joints and make it look like you have removed the weeds. Installing jointing material on top of that will just cause the weeds to regrow. If this is the case for your project, you are likely looking at a full lift and re-lay of the project. In this case you are removing the pavers, replacing the bedding layer, and re-laying the pavers. At this point, it may be beneficial to also lay the pavers at an increased slope up to 2% in order to allow water to drain faster off the pavement surface.
Preventing Moss Growth on Pavers
Unfortunately when it comes to preventing moss growth, there is little you can do once the project has been built. Moss will grow in damp spaces that does not get a lot of sun. If a project is being built in an area like this, then proper drainage is important. We prefer to build our patios at 1% slope which equates to 1/8″ per foot. However, with a patio that is not going to get a lot of sun and remains damp we will opt for a 2% slope which equates to 1/4″ per foot. This is still a completely acceptable slope and is recommended by ICPI. This increase in slope will allow water to run off the patio faster.
Ultimately, increasing the slope may not be the optimal option or it may not even completely solve the problem. It may be something that you may want to embrace with your patio. Some people really enjoy the look of moss and perhaps in a shaded area you should choose a more natural option such as natural stone such as flagstone or a square cut flagstone where you can lean into the moss growing in the joints of the stone to add to the natural appeal. There are also flagstone options for paving stones that create a similar look while embracing the technology of interlocking concrete pavers.