Box gulley gutter on loft extension - damp walls

We moved into a property 18 months ago and a damp problem started shortly afterward. The damp patches appear on the downstairs back wall of the house in the kitchen. There are several patches, some along the joint with the ceiling and a couple of larger patches (but more fluctuating in appearance) on the main wall - one close to the floor and one in the middle of the wall. See pictures. The wall nearly completely dried last summer in the warm weather but gets worse during rainfall. There is an almost vertical line on one area of damp (mid-wall) where one half is damp and one isn't - the damp patch appears solid to the brick when tapped and the non-damp sounds hollow. The wall is not a cavity wall.



The external wall is almost 3 storeys high (loft conversion) which was done about 10+ years ago. The wall is brick and the gutter is of a flat type that sites on top of the wall rather than overhanging, with a weather board on the wall. A downpipe runs from our roof to the neighbours gutter which is lower as they do not have a loft extension. There is a cable running on the outside of the wall at approx the height of the damp along the top of the downstairs wall but I don't see how this would cause it?

We had come to the conclusion that the damp was due to penetration through the wall which is south-west facing and receives the brunt of the weather. The wall had a poor paint job whic was flaking off. A couple of weeks ago we re-painted the entire exterior wall with 2 coats of pliolite-based masonry paint (after preparing surface), to try to waterproof the wall but allow evaporation. Whilst we did this we also checked the lead gulley gutter which was clear of debris and did not appear to have any cracks or damage.


We are now waiting and hoping for the damp internally to dry up and no more rain to penetrate. However during recent episodes of rain the damp patches have darkened leading me to believe it's not worked! During heavy rain we get large amounts of water dripping/blowing down the exterior wall from the weatherboard down the wall and onto the windows. Is there anyway to stop this? Is it possible to have gutters fitted that would catch the drips or some sort of overhang from the roof to protect the walls?

Any other ideas on where the water may be coming from?

Damp patches so far down a solid wall are more likely to be related to localised penetrating moisture, rather than the roof gutter.

Look more closely at the brickwork externally adjacent the dampness, and up to 1m upwards. Also check around the cill and frame of that 1st storey window

That middle picture of the stairs looks close to that odd external soil stack arrangement, so check behind that

Any slight crack in paintwork is going to let water in, but not let it out, so it moves inwards

Hi. Have you considered slate hanging? It often used on gable ends and alike where solid wall absorb moisture.

Thanks for your replies. We did think it was to do with penetrating damp at a lower lever which is why we recently repainted the outside with a waterproof (pliolite) paint.

The reason I mentioned the gutter is that due to the deisgn we get lareg amount of water dripping down from the roof down the wall so thought it could be exaccerbating the amount of water that could get into the wall.

If it is penetrating and we have now painted the outside, how long should we expect it to take to dry internally?

I do think we need to reseal around the windows, so that will be the next job - the windows are new but the problem occured prior to them being fitted. At the moment they are just mortered round the edges, no silicone.

Justlead1 - what is slate hanging?

Thanks

Hi Slate hanging = vertical slate (fix battens to wall and slate or tile) Before you do much more check out whether there is a damp proof course at top of wall, under any coping stones. I have often been require to fit lead capping on top of walls. Where coping stone have been used, builder sometime forget to form a drip grove in the underside of the coping, allowing water to run under and soak masonry.

Slate hanging is used quite a lot in Somerset on exposed solid walls like this, and is more effective than rendering but more expensive.
The drying out time could be months rather than weeks depending on how much water is in the wall and the heating and ventilation inside.

If the areas have recently darkened after rain, then that would indicate that moisture is still penetrating, and the wall will not be drying out