Mortar seems to be earth/soil?

[dextermanly]

Please help!

I am preparing my external house walls for repainting and have discovered that some of the mortar is soft. Upon investigation, when I scrape it away it seems to be a rather black soil! My house was bombed during WW2 - might they have used an earth-based mortar (is there such a thing)? When I moved into the house there were damp issues and I had a chemical damp-proof course put in about 10 years ago.

The earthy-mortar is only present up to about five or so feet from ground level - but has obviously been present quite a while as it is behind the earliest layer of paint as far as I can see.

Any ideas?!

 

[JohnD]

I have seen this below ground level in damp or wet soil where pipes or drains have been leaking long-term. I have assumed that the soft lime mortar washes away and mud fills the gap.

In my case I usually wash out the mud with a hose, in small sections, and pack the joint with stiff mortar, rammed all the way in and packed tight. Let the bricks dry out enough that they do not turn the mortar to slop. You may need to dig down to repair all the damage. Do this in small sections to avoid undermining the wall and giving it the chance to move.

When it's underground, it does not matter if the mortar is untidy. If on show, consider a mortar-pointing gun, which injects the mix into the gap and can be used to give very neat results.

 

[dextermanly]

Many thanks - very helpful!

 

[vinn]

Do you have solid or cavity walls?
What kind of paint is on the walls - a heavy plastic paint or a masonry wash? "layers of paint" would seem to indicate heavy coatings of paints.
Why not post photos of what you have exposed?

Its very doubtful that "mud" has made its way five feet above ground level.

 

[r896neo]

Mortars made from fly ash and other nasties appear very black and can be very weak and crumbly. I wouldn't describe them as being like mud though...?