Stone footing repair

[mark b]

Hi,
I have a problem with the stone footings on 1 side (North) of my 1920's built home. When we bought the house, most of the mortar between the stones had fallen out and following advice, I used a sand (local washed creek sand, lime and cement mortar to fill in the holes, smooth off and then paint. 5 years later the mortar is beginning to fall out again. The stones are also quite crumbly in places. I think I must have bridged the damp course (a 10mm thick layer of black sand???) in one place resulting in some fretting of the stonework above. Can someone advise as to how to permanently fix this problem. Would concrete and form work be the best solution?

Thanks for any sound advice
Mark

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[ozwinner]

Your damp course has hit its use by date.
The black sand is mortar with bitumen in it.

Try this stuff. http://www.techdry.com.au/rising_damp/rising.htm

No affiliation etc, but ive used it on my own place with good results..

Al

[mark b]

Hi Ozwinner,
Thanks for your feedback. Apart from the small section of wall where I reckon I bridged the damp course with mortar, the wall above is sound with no sign of moisture or fretting. The inside walls show no sign of paint lifting or moisture. The problem seems to me to be in the stone footing below the damp course. Why do you think that the damp course would cause them to decay as they have? I can't really see how using the tech-dry product would stop this.

Mark

[ozwinner]

Hi Ozwinner,
Thanks for your feedback. Apart from the small section of wall where I reckon I bridged the damp course with mortar, the wall above is sound with no sign of moisture or fretting. The inside walls show no sign of paint lifting or moisture. The problem seems to me to be in the stone footing below the damp course. Why do you think that the damp course would cause them to decay as they have? I can't really see how using the tech-dry product would stop this.

Mark

The dampcourse is set too high, its the salts in the ground that rise up into the stone that causes the "weathering" effect.

If you inject the damp proof lower down it will stop this, although some blocks look past their use by date.

Maybe you need to get some sort of architectural survey done to asses the problem properly.

Al

[mark b]

Thanks Al.

Looks like the problem is more serious than I thought. Will see if I can find someone local to have a look.

Mark