Will the 7/8 parts sharp sand, 1 part lime mix, and 1 part OPC and the surface pointing mix be strong enough to hold it's shape on the decorative stringing, and yet be fully breathable? I know that the pointing of this will have to be done in a few stages. No need to worry...there's no way I'm going to put on a hard mix....that's botch job area!
I'm just wanting to clarify that this is the porch I'm talking about here. Mix should be able to retain shape ie.ridgety (opc).
The other thing I was on about was a seperate plain wall of the building which I thought the original mix was the victorian 3-1, so was planning to use the same.
1st Mortars with any amount of cementous binder will not 'breath' as well as pure lime receipts, the will store water and diminish capillar activity to dry out rain.
2nd Sharp sand has to few fine parts to get a good adhesion, the main thing before the carbonisation will make it harder.
3rd The cement and its typical gypsum additive will build up ettringite needles in the pores which will bring more water and crack risk in the structure.