Wet on internal wall on outside corner of house

longwalks1

In our 1930’s semi detached house, the outside corner of the house (on the inside) wall is damp/practically wet.  It happens to be our staircase, which has a high ceiling (approx 4.5 metres high in the corner).  The wet is over a lot of the wall, if you catch it in the light you can see wet run marks on the painted wall.

Also noticed a few spores forming in the corner of the wall about half way up the stair case.  A wipe got rid of them, but they were there. 

aside from us always giving a not overly warm hallway (all the heat from the radiator obviously finds its way straight up the stairs), nothing isn’t as it should be.

any ideas please what’s causing this, and what needs doing to correct it? 

Thank you everyone in advance 

FreeBear

If the wall is wet half way up, it isn't going to be rising damp, so don't get conned in to having a chemical injected DPC and/or waterproof render/plaster slapped on the wall. Instead, look at the roof, in particular, the gutters & downpipes. You may have a tile or two slipped on the bottom row, or if the downpipe is blocked, water overflowing and soaking the wall. Best time to check is during a heavy downpour, which I'm sure we will get a few more of between now and the new year.

Upper half of the property rendered ?

Check for cracks and repair where necessary.

longwalks1

hi FreeBear 

many thanks for your reply.  I’ll get the roof and gutter checked as soon as I can (I’m actually going away tomorrow) so will check it as soon as I’m back. 

Yes, the upper half of the house is pebble dash (and I’m guessing it’s 90 years old) so will take a good look once I’m back 

longwalks1

Morning FreeBear 
been thinking and 2 things changed last week a couple of days before we noticed the wet spots, probably nothing.  

Firstly, we refitted the hallway radiator about 3 or 4 days before spotting the wet areas. And, secondly, mrslongwalks used a carpet washer on the stair carpet directly below the area? 

Could either of these have possibly caused or contributed to the wetness?  Or just wishful thinking? 

stuart45

It's possible that condensation has been forming on the walls with moisture coming from the carpet. Mould likes the pure water from condensation.

longwalks1

stuart45 said:

It's possible that condensation has been forming on the walls with moisture coming from the carpet. Mould likes the pure water from condensation.

Thanks Stuart, would the cold hallway/stairs also of added to that? (Having had no radiator in there until recently) 

stuart45

Having cold walls will add to the cause. One way to check on areas likely to suffer from condensation is to check the temperature of the wall with a surface thermometer, and compare it to the air temperature and R/H. 
Condensation often shows up as streaks down the wall.

longwalks1

stuart45 said:

Having cold walls will add to the cause. One way to check on areas likely to suffer from condensation is to check the temperature of the wall with a surface thermometer, and compare it to the air temperature and R/H. 
Condensation often shows up as streaks down the wall.

Thanks again.  II’ll check wall and air temps as soon as I’m back.  The wall that is wet is absolutely freezing to touch, and the wetness is streaks/run marks from about half way up down to the skirting board.  Almost looks as if someone’s wiped the wall with an overly damp cloth and the excess has run down the fastest routine to the floor

FreeBear

A damp wall sucks up heat and promotes further condensation which just exacerbates the problem. Whilst the carpet washer might have contributed to the problem, the radiator won't (unless there is a leak).

Depending on where you are in the country, it looks like some of us are going to get some heavy rain over the next couple of days - Ideal opportunity to see if the gutters are overflowing.

longwalks1

thanks again FreeBear. I’m in Hertfordshire, but going to be away for a couple of weeks so won’t have anyone to check til I’m home sadly - not perfect timing.