The ground moves. Patios move. The first casualty of this movement is usually the cement joints in between the patio or paving slabs.
Repointing need not be the huge dilemma a great many of our users have found it to be. For example there is no need to point it as you would do a brick wall.
Brickwork pointing is designed to go hard quickly and is not at all flexible as you can see by cracks in many new houses.
If you have a patio which has been pointed this way then follow our pointing brickwork project as the principle is the same. You may need to match the sand and cement for the right consistency colour and we have a matching mortar project for that as well.
Clean out the Existing Patio Joints
For new patios, or patios and paving where there is not a lot of the existing pointing left, its better to cut out all of the old stuff and start again. A hammer and bolster chisel are the best tools for this, along with a plugging chisel (images below) for tight joints.
Do not attempt to use an angle grinder unless you are used to handling one as they can quite easily skid across the surface of your slabs, marking them badly.
Repointing Patio Joints
Once all the joints are clear you can start pointing. The mix of sand and cement you will use will depend on the width of your joints. Pointing of all kinds should be carried out on a dry day and when your patio itself is dry.
For joints which are less than ½ an inch (13mm) you should use silver sand. This is more commonly called playpit sand. The sand is mixed with cement at a ratio of 1 to 1 and spread out to dry thoroughly. Do not mix on the patio.
Using a bucket, sprinkle this mix along a couple of joints. Using a soft brush, brush carefully sweep it into the joint. Make sure the joint is absolutely full even to the point of tamping the mix down with a piece of timber.
The most common cause of patio pointing failure is when voids are present either within the joint or under it. These are easily formed when a lump of sand clogs up the joint and it may look as though this joint is full but in fact it is not. Water soon gets into these voids and with a freeze-thaw action soon destroys the rest of the joint.
When the joints are full, brush any surplus off the surface and leave. The moisture in the air, plus the moisture from the ground underneath will send the jointing hard in a while.
This slow hardening process keeps the joint flexible and, providing you have filled the joints up, they will not crack.
Patio Joints That are Wider Than Half and Inch
If the joints are wider than ½ an inch, the same procedure can be followed. This time use sharp sand and make sure it is dry and ALL the lumps are squashed. This should be mixed at 3 sand to 1 cement. This makes it slightly leaner and even more flexible. It should be left to dry in the same way.
Patios can be pointed quite quickly using this method and providing everything is dry there need be no staining of the slabs associated with ordinary pointing.
It is now possible to purchase bags of premixed patio jointing sand so that all you have to do it empty the contents onto the patio surface and sweep it into the joints. Your local DIY store should stock a range of these.
All project content written and produced by Mike Edwards