Streaks on north facing external wall

[Stattman]

Dear Forum,

Seeking your advice regards to some streaking on a wall which is the back bedroom facing north.

Can’t be certain how ling the issue has been there but was noticed several weeks after the room had been painted. As shows in the pictures the streaks run across the length of the wall. There used to be an air brick in the far left which was sealed (as it was very cold and the thinking being the trickle vents would be ok).

The room itself doesn’t get used and with its location gets hardly any sun. The radiator was also put on the opposing side by the previous installer).

Would appreciate any initial ideas to try out, the obvious one being; paint and see if it works.

Thanks
Mark

 

[^woody^]

Looks like extreme condensation.

Is that a roof or a floor above?

 

[Stattman]

Thanks for your reply.

It’s a roof directly above, it curves down. It only seems to be this room. My decorator suggested it may be lagging which is stopping circulation however we both had a look and it’s not causing a blockage.

A few suggestions been mentioned and up for grabs:

- Do nothing, paint and see
- Re-open the vent (I.e. trickle vents aren’t sufficient)
- add vents into the soffits outside to aid in circulation
- relocate the rad to under the window

One or more of these may work, but would like to try the quick and simple items first, or anything else which would be worth considering.

 

[^woody^]

It may be a one off event, either the moisture from the decorating or a cold snap and the other house heaters on high.

Normally this is caused by lack of insulation, or cold blowing in at the eaves which makes that corner colder than other parts of the room.

Repaint and see what happens.

Trying to solve this by altering the internal environment is trial and error., but think about how the room is heated/used and if the door is kept open or closed. You want to avoid hot and cold extremes, and warm humid air migrating to that room from the other parts of the building.

 

[Stattman]

Thanks!