Condensation or Penetrating Damp???

[DIY'er]

Happy New Year everyone.
Hoping some damp experts out there can help me out with this one.
My property has damp under my bay window. My first thought was condensation, as it is probably the coldest wall in the room, the heating has been on a lot over winter and there is usually a sofa in the bay window. I repainted the wall in question 6 months ago and there were definitely no signs of damp. Could this be condensation build up or is it possible that penetrating damp has appeared within 6 months? I've added a few pics.
Thanks in advance.

 

[EFLImpudence]

Condensation.

Do not put the couch or anything against the wall.
Apply neat bleach to get rid of the mould.

 

[DaveHerns]

Can we have a photo of what's on the outside of the window ?

 

[John D v2.0]

It's very mouldy so I'm going with condensation. If it's that much colder than the rest of the wall, presumably there's a thermal bridge. Or it could be excessive humidity.
If it's an excessively cold wall I'd be tempted to line with a thin layer of celotex and plasterboard, but if your humidity is high it'd end up condensing elsewhere.

 

[vinn]

It appears to be "Black Spot" condensation - however, there are indications that previous "remedial" work has been done in the bay.
As above, thermal bridging could be playing a part?
If you are on the ground floor with a cavity wall then it could be cavity debris blockage bridging?

Leaving the bay clear of furniture and watching and waiting for a few weeks will give a more clear indication of whether its simple condensation or perhaps something a little more complicated?

 

[Blagard]

DaveHerns is right , lets see what is outside that bay with some photo's

Check your guttering and make sure water is going down the pipes and not elsewhere.
Is the ground outside high relative to the floor inside?
What is the wall construction or if you don't know what is the age of the property and where is it?
How long have you lived there - if you moved in just before painting it, it would be summertime but should still show signs of previous wetting. So what has changed.?

That wall looks wet in places and certainly you have some condensation but that may be secondary to wetness due to another problem. Any outside wall that is wet through will conduct heat away creating conditions for condensation.

 

[DIY'er]

Thank you all for your replies, I have the answers to your questions below;

The furniture in the bay window isn't up against the wall, there is a gap.
The house is over 100 years old and I have lived here for 6 years with no previous problems.
The ground is low relative to the floor inside.
I think the wall is a 2 skin red brick wall with a cavity and external render, and to my knowledge there has been no previous work done apart from double glazing being installed about 5 years ago.
I've attached a pic of the outside, there doesn't seem to be any obvious crack or damage in the render that would cause water to get in.
There is a gutter but in runs to the side of the bay window and isn't leaking.

Thanks.

.

 

[Blagard]

Judging from the angles in the first photo's the damp is at the corners just before the main wall.

On the one side I would check that downpipe when it is raining to make sure water is not coming out of a bad joint and soaking the brickwork or even if the drain is blocked. However that does not seem likely to be repeated on the other side hidden behind the bushes, but is the runoff from all those leaves going down the side of the house? I would certainly recommend cutting the growth back. Other than those potential issues I can't see anything else externally that would would cause the the wall to be wet and cold where previously they were OK

I seriously doubt you have a cavity wall construction although you may have two skins of brickwork the gaps between them will be full of bits of mortar and every now and then a complete brick will be laid across the two skins. That will be what I would call a solid 9" wall. So any external soaking can easily be transmitted through to the inside.

 

[vinn]

Does the window sill have a drip throating groove underneath - it should run all around the sill pieces?
The PVC frames seem to have been recessed into the render - & the bottom rails are not true sills and dont project to shed water as sills should.
Do your frames open?

The plinth like piece that also acts as a lintel over the basement door - the top edge of this plinth forms a lip or ledge, and could be holding water that then penetrates through the render and brickwork.
What kind of paint is on the render?

If no satisfactory cause can be found, & you've waited and watched for a change, then its best to knock off all affected plaster ie. from floor to window boards, remove the skirtings, and render with sand and lime or DriCoat or similar remedial plaster.

I presume that you've researched condensation & the householders possible part in causing it?

 

[scruffybiker]

It's condensation. I get exactly the same on my bay window. It's due to the fact that all the exterior walls are solid double skin. Then out bay is single skin stone so always colder..

 

[scruffybiker]

I find leaving the window on the catch overnight / late evening solves it completely

 

[Blagard]

It's condensation. I get exactly the same on my bay window. It's due to the fact that all the exterior walls are solid double skin. Then out bay is single skin stone so always colder..

There is no doubt there is condensation but you are wrong about the single skin to the bay. While some houses have a single skin this one does not. Also be aware the OP has been there 6 years and this is the first time the problem has appeared. - So it is likely something has changed. Vinn correctly points out that a change in lifestyle can cause condensation e.g. drying cloths in the room, closing windows that used to be kept open, in fact anything that will increase the the humidity levels.

At the moment I suspect the wall may be colder than it used to be (this can cause condensation due to the surface now being below dew point where previously it was not). A wet wall (through and through wet not just the surface) will conduct the heat away faster than a dry wall so given the history of the house for 6 years and the potential for wetting the wall those issues need to be checked and eliminated.

 

[DIY'er]

Thank you all again for your responses.
The damp patches are actually in the middle and left hand side (looking at it from the outside like the picture)of the bay window.
The black plinth does have a drip grove and there is no water running down the face of the render. The paint used is regular exterior masonry paint.
I have cleaned the area and will take notice of the advice to lower the humidity in the room. I will watch it closely over the next few days/weeks to see if it reappears!