When it needs to be done
Repairs to ridge pieces will need to be done if there are leaks, if the mortar is missing (a common problem after a bad pressure wash) or the pieces are loose.
Re-pointing the tiles in areas with diverse weather conditions is not recommended as the grouting tends come lose. There are many products out there to help with flexibility & adhesion which we will cover another time.
How to do it
If the tiles are loose they are going to need to be relayed. Removing the mortar is easy enough work if they are ready to be repaired.
To clean the tiles tap the mortar lightly with a sharp chisel.
Next you need to run a builders line (or use a straight edge) to keep your line.
Lay the mortar 50mm x 50mm away from the edge to avoid the mortar mix falling in the cavity. You can use your old mortar pieces or broken tile bits between ridge pieces to support the mortar.
Start laying at one end and tap the tile lightly a couple of times with the back of the trowel to set it level into the mortar. Continue by laying another bed of mortar either side and installing your next tile, tapping it lightly to set and level it. Patience is the key, avoiding trying to lay to many tiles before neatening up.
Getting the correct water ration is crucial. It needs to be 1 part cement to 3-4 parts sharp sand and a minimal amount of water. If the mix is too wet you will leave many marks and there will be too much slump, making it difficult to use your trowel.
We use a large and small trowel and a 20L bucket. If you are working alone we recommend using 5L containers and using a hoist to pull it up.
If you make the mortar too wet, wait before trying to neaten it up. Let it settle and float it. If you do mess, do not attempt to lightly hose or wire brush the mortar before it has settled.
A last resort to fixing the ridge pieces would be to paint the roof capping in a waterproof paint.