Above shows just how effective windblown rain is at eroding the mortar and dashing on an exposed site.
- large holes need to be cleaned out using a long screwdriver or thin trowel
- take back to sound mortar – dont over do it as aged mortar is soft
- brush out recesses
- first pile in mortar
- do not have deep holes full of mortar – fill with appropriate depth stone – big first and over lapping to knit everything together
- I use mallet with steel chisel to make a sound filler – do gently
- fill with smaller stone to outside
- now get thin springy trowel and work more mortar in
West facing gable – notice wall has only been repointed where mortar is missing – there is oold dashing above cleaned up part of wall so the mortar should be ok but if is in anyway soft I tend to take it off as it eventually will fail and drop off.
I filled all the holes on the outside of the walls – this adds to the walls integrity and prevents easy access by wind blown rain from coming inside.
This is the other gable and is facing east – so is much more sheltered then the west facing gable that takes the brunt of the weather and the hot sun in summer ( some years that doesnt happen though)
Dashing that I use is NHL 3.5 and mix is strong – 1:2.5 – for me it provides a strong bind and is similar in some respects to a cement mortar – not as strong but breathable.
I use this mix inside as well for inside dashing to provide a good grip for plastering over