Steve wrote:
Hello.

I am totally confused! I need to do some repointing on my Edwardian semi.
From investigation I'm led to believe that lime based mortar would have
originally been used. However, there seems to be lots of, often
contradictory, information about the type of mortar I should use.

OK, a few basics.

There are 2 basic types of mortar: lime, and cement. (Lime & cement
mixes are all of the cement type.)


Cement mortars on soft brick cause 3 problems:

1. Bricks breaking due to normal movement. Lime mortars are softer and
will crack instead of breaking the brick, which is very much
preferable. Also lime mortars self heal by recrystallising across the
cracks.

2. deterioration of bricks due to freeze damage.
Lime evaporates damp from the wall, cement doesnt, so water at the
brick surface freezing causes bricks to slowly disintegrate in some
cases.

3. Damp: lime allows the evaporation of damp, cement does to a much
lesser extent.


So lime mortar is much preferred, although cement will work.

Cement mortar: there is only one reasonable choice, 1:1:6. 1:2:9 is now
known fail prematurely.


Lime mortar:

You can mix hydrated bagged lime into a putty, store it in a closed
container for a few weeks and use it 3:1. This is easy and cheap. Other
options are buying lime putty or using bagged lime and water without
storage. Cover the job for a while so hard rain doesnt wash it out
before its hard.


Sand: use whatever the heck you want. From your pic, use the gritty
sand, and add some lil bits of chalk if you can find it and want it to
look the same. What you have is lime mortar, cment will never match it.


NT