Dampproofing party wall

[LLondon]

Hello. I'm new to this forum, and would appreciate any advice on the following please. (Please bear with me if I'm asking daft questions )

We had a chemical DPC injected to our front lounge wall about a year ago, under and to the sides of the lounge window. It's a Victorian terrace.
We've since had a small damp patch appear towards the bottom of the party wall where it meets with the wall that was damp-proofed.

I've had a number of contractors round to quote for remedying this damp patch. All recommend injecting a DPC for about 1.5m along the party wall, as well as replastering a section of the wall.

Any thoughts from folks with more knowledge of this sort of thing than me would be much appreciated on:
1) whether you think it sounds like a DPC is the right approach to our damp issue.
2) the effectiveness of injecting a DPC only from one side of a party wall (which is 9 inches thick). If the chemical is not injected all the way through (ie not injected from the neighbour’s side), would capillary action of the chemical ‘protect’ the remainder of the width of the wall?

Thanks in advance.

 

[gregers]

iirc from when i used to do this type of work we never guaranteed party walls.

 

[^woody^]

It is very difficult for moisture to get around the treatment of one side of a 9" wall, and will tend to show more so on the untreated side and climb a bit higher that side too

 

[LLondon]

Many thanks for the responses above.

Woody, could I just clarify with you please - do you mean that the moisture would tend to show more on MY side of the wall after I'd had the damp-proofing done?

 

[^woody^]

No, - that should be untreated side - I've edited my post

It will have to travel up the neighbours [untreated] part of the wall and then move back over the top of the treated area on your side.

This will cause the moisture to not only be more noticeable on their side (if it is a significant amount) but it may also evaporate away before it has chance to soak back towards your half

In any case the contractor should be replastering with a water resisting plaster, render or cement slurry