Damp on internal wall above skirting

[Pallatrax]

Hi guys,

My parents have an old place that was partially rebuilt a decade or two ago, and some of the original walls don't have a proper DPC.

It is one of these internal rubble-filled stone walls that has a 3m wide damp patch up to 200mm above the skirting creating a 'tide mark' that is an uneven horizontal line.

The house had a DPC injected when it was rebuilt, and this particular wall was treated again a year ago, but the problem wont go away.

The damp is at least 3.5m away (horizontally) from any external part of the house but there is a chimney breast 1.5m away.

Is it possible water is getting into the 'cavity' of this old stone wall and making it's way undetected to ground level? The house has a 2nd floor, so it is a long way to go, but due to the nature of the roof, and shape of the house, this 'internal wall' becomes external where old house meets new section between the 1st and 2nd floor.

There are also valleys in the roof, so it is plausible a good quantity of water could enter the roof/walls I guess?

Any thoughts??

Thanks
Tom

 

[mattice]

We had similar symptoms.

House renovated by previous owner, floors replaced by membrane and concrete. External walls fine, plenty of opportunity for water to evaporate outside, some internal walls have a tide mark through summer and autumn before we put the heating on which presumably helps with evaporation.

Previous owners also had a couple of attempts at chemical damp course and re-render. Both have failed.


I dug a french drain outside 6 months ago. Problem now sorted… for now

 

[Pallatrax]

Hi, and thanks for your reply.

Drainage around the property looks fine. There are gulley's that lead to (unblocked) soak aways which also carry the rain water from the roof...

This internal wall is 3.5m from outside ground, so I'm struggling (although not ruling out) to understand how it can be 'rising damp' from just wet ground - does it really seem plausible?

Thanks
Tom

 

[JohnD]

Might be a leak from a buried water pipe or a radiator or a sink.

Have you got a water meter?

Is it wet under the floor?

 

[Pallatrax]

I hadn't thought about the central heating, and now you mention it a lot of it was (seemingly) buried in the walls.

I don't have a meter.

I'll have a word with the old man and see how often he has to bleed the system!

Thanks
Tom

 

[JohnD]

if the CH is fed from a feed and expansion tank in the loft, see if it keeps filling itself up or; if you tie up the ball float for a week, does the water level drop.

 

[Pallatrax]

Yes, I think it is! That is a really good shout - I'll let them know and ask this old man to tie that up!

Thank you
Tom