Moisture on external wall of victorian house

[triz]

Hi all. I'm looking to buy a semi-detached victorian house, and have recently noticed a large patch of moisture on the exterior wall of the house. Does anyone know what could be causing this? It follows an unusual pattern, coming down vertically from close to where the guttering is, but then extending all the way along horizontally at the bottom. There are no water pipes on the inside where this patch of dampness is, so I'm really not sure what could be causing it, and am worried it might be a headache to rectify. Any ideas?

 

[Cubist]

Is there a bathroom in that corner of the house? If so, you may be seeing the evidence of an internal leak from a bath/sink/wc or perhaps even a failed or missing overflow pipe from one of these. I'm guessing but that looks like water running down the internal wall indoors and the collecting and perhaps pooling on a solid floor on the ground level.

Given that this may be a cavity wall then its possible that a failed overflow pipe could have leaked inside the cavity to produce this effect.

 

[Stevers]

Also worth checking for either a leaky gutter joint or a droopy blocked gutter.

 

[Cubist]

I'm having too many afterthoughts these days but...

It's not unknown for plumbers to install an overflow pipe from a water tank sited in a loft and route this to exit at the eaves of the roof. A failing washer in the ballcock filler for the tank could be responsible for this if the overflows exit has been disturbed in some way.

 

[triz]

Is there a bathroom in that corner of the house? If so, you may be seeing the evidence of an internal leak from a bath/sink/wc or perhaps even a failed or missing overflow pipe from one of these. I'm guessing but that looks like water running down the internal wall indoors and the collecting and perhaps pooling on a solid floor on the ground level.

Given that this may be a cavity wall then its possible that a failed overflow pipe could have leaked inside the cavity to produce this effect.

There's no bathroom in that corner, just a bedroom. But the pooling theory makes sense, unless the source of the dampness is external, for example in the case of a broken gutter joint - in which case I'm not sure how the dampness could travel horizontally like that.

Also worth checking for either a leaky gutter joint or a droopy blocked gutter.

Yeah looking at the corner gutter joint at the top, this looks like it might be a likely source. I'm just not sure how it would create the horizontal section at the bottom.

 

[a twig]

Horizontal along the bottom could be rainwater splashing back up from the tarmac outside which to me all points back to the guttering not doing its job.

It looks from the photo that the last run of the gutter is ever so slightly uphill to the down pipe, so If the down pipe is blocked the overflow would happen pretty much exactly where the vertical damp is, plus during heavy rains it will likely overflow all along that length, creating the heavy splashing resulting in the horizontal.

 

[Stevers]

I'm just not sure how it would create the horizontal section at the bottom.

I wondered that, but it could be below the DPC that a house with cavity walls might be expected to have - it looks to be in about the right place. If slate I think you'd expect to see a thicker mortar course though.

Just noticed that fine crop of tingles on the hip roof, so that could be coming up for renewal.

 

[larry]

Have you had a look at what's happening during any heavy rain?? Seems weird the bit on the left would stay dry if it's splashback, but maybe the guttering is doing enough of a job there?

Also what's that pipe/conduit in the middle?

 

[lizziecupcakes]

I’m sorry, I have zero ideas except maybe what others have already said and suggested - a leaking pipe that sits very close to the external wall? Maybe the water is pooling at the bottom too, hence that strange shape.

Just curious, but have you asked the vendor and estate agent about it?

 

[lizziecupcakes]

Also, maybe it’s just me, but is the chimney anywhere near it?

 

[triz]

Have you had a look at what's happening during any heavy rain?? Seems weird the bit on the left would stay dry if it's splashback, but maybe the guttering is doing enough of a job there?

Also what's that pipe/conduit in the middle?

Yeah seems weird to me too, will take a look when it's next rains. I think the conduit is part of the electrical wiring.

I’m sorry, I have zero ideas except maybe what others have already said and suggested - a leaking pipe that sits very close to the external wall? Maybe the water is pooling at the bottom too, hence that strange shape.

Just curious, but have you asked the vendor and estate agent about it?

No haven't checked with them yet, will definitely do that and report back.

Also, maybe it’s just me, but is the chimney anywhere near it?

There is a chimney breast nearby on the inside, but it's to the left of where the damp patch is, and doesn't have an actual chimney on the top.

 

[lizziecupcakes]

Thanks @triz . It really is strange .
Having another look and maybe, just possibly, before you came for the viewing there was some graffiti or something yucky and they had it washed it? I’m guessing really.

I would go to the property a few times at different times of the day and take photos. See how it appears/disappears.

I would ask the EA and vendor for sure maybe in an email too?

I’m not sure a surveyor would be able to tell you much more - they would only really give you an educated guess because they usually don’t lift floorboards or anything. you wouldn’t really know the real cause until you bought it and had it investigated yourself.

 

[Lacan07]

I would find a brolly and visit the property when its raining, your first port of call is broken guttering.