How do I choose a suitable mortar for pointing masonry?
Firstly, as a basic principle, the mortar should always be weaker than the surrounding masonry. Issues such as substrate type and condition, site exposure, time of year, ease of use and compatibility with existing mortars must also be considered. The choice of aggregate is also an important factor. Sharp, well graded concrete and building sands are generally used in lime mortars for most pointing where mortar joints are 10mm or wider, a sharp concrete sand is usually appropriate.
