Repairing patio including removing mould and repointing Post your questions and get answers regarding all areas of drives, pathways and patios

[Mat888]

Hi
I have recently move in to a new flat and want to refresh the garden patio. It has buff coloured tiles which have quite a bit of mould blackspot on. I am going to pressure wash to clean them but then also need to grout them (all of the previous grouting has decayed). The gaps are of varying sizes (approx 5mm to 30mm), can anyone advise the best mix for this? I was planning on using a dry mix with three parts sand and 1 part concrete.
Also the slabs were laid on soil rather than a concrete base. Some slabs are stable however a small number move when i stand on them. Can anyone recommend how I can fix these slabs to the ground e.g. lay them on self levelling compound?. I asked a couple of people to quote for repairing this but got quoted £2k which is outside of my budget.
Thanks
Mat

[stoneyboy]

Hi mat88
Lift the slabs that are moving and use sharp sand to level stabilise them, also try to even out the joints.
Use 4 parts sharp sand to 1 cement for the pointing but since the slabs are laid on soil the pointing will have a short life.
Regards S

[Mat888]

Thanks for the advice!

When you say short shelf life, do you think it will last a few months or potentially even less?

Matt

[stoneyboy]

Hi mat888
It all depends on how firm the ground is underneath the slabs. If you force the pointing down well into the joints this will partly help stabilise the slabs. Assuming you are not going to drive a car over them they should be ok for this year. If we get a period of prolonged cold this winter ground heave will lift some of the slabs so expect to redo some joints next year.
Regards S