What kind of damp is this? Any help appreciated!

Star Spangler

We noticed mould behind a cupboard in a bedroom starting from the skirting and rising half way up the wall.

On the outside wall I took these pictures.







Would anyone know what kind of damp this is?
What is causing it?
How can it be treated?

Thanks for any help!

DOCARCH

Star Spangler wrote: »

...rising...

Hard to see the photos, but, I think you answered your own question! Looks like rising damp.

What age of house is it? I that self-coloured render in those photos? What is the level of the ground outside in relation to the floor level inside?

Drift

Any chance of bigger photos OP - those ones are tiny!

As DOCARCH mentioned it looks like self coloured render. Some types of self coloured render can look "damp" when they are wet after heavy rain. Is there internal evidence of dampness?

Larger photos and one or two showing the location in context might get you more answers.


Edit: Apologies I missed the description of the internal dampness within the house - what age is the house? Can you show us pictures of the internal mould growth.

DOCARCH

Drift wrote: »

As DOCARCH mentioned it looks like self coloured render. Some types of self coloured render can look "damp" when they are wet after heavy rain. Is there internal evidence of dampness?

Self coloured render will often suck up moisture from the ground, so always better/best to finish with a plinth of sand/cement render at ground level.

In the OP's case, possibly the damp proof course (if any) has been bridged by the render?

Star Spangler

I can't figure out to put up the photos any bigger - sorry!

The house is originally built in the 1940's. It was renovated and extended in the 1980s when the coloured render was applied. The wall on the left is the old original non-cavity wall which is maybe 18 inches thick. The wall on the right is a cavity wall from the time the house was extended.

We've lived in it 10 years but this damp has only appeared in the last year.

DOCARCH

Star Spangler wrote: »

The house is originally built in the 1940's. It was renovated and extended in the 1980s when the coloured render was applied.

Where are you seeing the damp internally...the 40's bit, or, the 80's bit?

As I said above, I reckon the render is bridging the damp proof course, even if this is only showing up in the last year.

First simple thing you could do is dig a little trench around the external walls/reduce the soil level just where it meets the external walls.

Star Spangler

Thanks for the advice Docarch. I'll give that a go.

The damp is in the 40's bit internally.

DOCARCH

What you need to do longer term is basically put in a french drain (you can google that) around the perimeter of the house, and, take off section of render below floor level, to stop the water being sucked up.

Should be easy enough to resolve, but, I would also suggest you get some professional advice to look at the issues inside and out. Note of caution...don't let somebody advise you to inject a chemical damp proof course...they help, but rarely work 100%!

If this is only happening in the last year, also check your gutters/down pipes are not leaking in that area. Leaky gutters/down pipes are often the cause of damp at ground floor in older houses!

Drift

Also check for a burst CH or water pipe. These can also be responsible for "sudden onset" damp rising from the floor area.

Strolling Bones

Star Spangler wrote: »

We've lived in it 10 years but this damp has only appeared in the last year.

Did you do something recently externally - like form a raised planter bed ?
Thereby bridging over the DPC ?