I am about to re-point the front of my Victorian (1895) house which has soft red bricks.
Is a 4:1 ratio of sand to cement suitable?
I have read that cement can force the moisture though the bricks and cause issues, and therefore some people suggest lime instead of cement.
What colour sand is most common for the mortar in this case?
Do people tend to use red sand, or a dye of some sort?
Best Answer
Please don't let a cement based mortar go anywhere near your house! Definitely use a lime based mortar. I won't get into specifics as it's very location dependent, but a quick google search of the options available in your area should find a nearby supplier. Usually either a tubbed putty or a bagged powder mixed with sand or if you're lucky, a complete pre-mixed mortar ready to use from the tub after a mixing to liven it up.
A basic lime:course sand mix would be around 1 lime to 3 sand. Sometimes a little stronger 1:2.5 or so.
The sand needs to be clean and well graded, not too many large stones/grit. I sieve my locally available sand as it's mostly a little too coarse for the fine joints I encounter.
It's a big subject though, with more than a few do's and don'ts. Firstly make sure the joints are actually ready for re-pointing. If you need to rake out lots of mortar to get a nice deep joint then maybe it can wait a few years (cracks excepted).
Secondly, clean out the joints and moisten them well before packing in the dryish mortar. Keep the finished pointing protected and damp for a week or more. Slower the better.
There is some good stuff on the thisoldhouse dot com website.