Damp (“rising”?) walls - gable end.

[Danrees]

Hi,
This forum has come up many times when searching for similar damp problems so I thought I’d sign up and share my problem in the hope of some advice.

It’s a 1900 solid wall house.

I am renovating my downstairs - upon removing wooden cladding and thick wall paper I’ve realised I have quite the damp problem. It seems to be contained to the gable end - ground floor.

From reading other threads on here:
- The ground levels externally seem too high.
- The concrete plinth also seem to come down too far and possibly leads to the DPC being breached?
- The render isn’t ideal but don’t wish to remove this

If rain water is coming in from the gable end external floor and breaching the DPC via the plinth, would the damp be this high internally on the walls?

Also I’ve noticed that the damp patch internally on the walls does not get any bigger (drawn around it) - just darker after heavy rain.

Do you guys think I’m on the right path?

Would removing the concrete plinth, repointing the stone/bricks behind and installing a French drain be a solution? Internally I plan to hack off the walls and try and dry them out - then use insulated plasterboard.

I’ve attached pictures of the gable end and plinth and the walls inside.

Thanks for any advice
Dan

 

[Mr Chibs]

I'd knock the render off, below the dashing, try to find the DPC and have no render below this.

Then either lower ground level or dig/cut a trench spade deep 150mm wide along wall, fill with larger pebbles when you can, so air con circulate.

You might want to pull a floorboard up as you may have damp/rotten joists.

I had all this at my place.

 

[Danrees]

Hi,
Thanks for your input.
I think there is at least one rotten joist which I will be addressing once the damp problem is solved.
So below the dashing, I would just have exposed bricks? (Which I’ll repoint)
Will the DPC be visible?

Is The idea of the trench to ensure any water that finds itself against the house will be below the DPC? And therefore not able to come through internally?

Did you solve your issue in the end? Seems to be quite common!

 

[^woody^]

That pattern is not typical of rising or penetrating damp, but of condensation damp - and the location would support that too.

 

[Danrees]

Thanks Woody.
The house has been empty for 6 months (no heating etc). I’m assuming this hasn’t helped things

 

[foxhole]

The render will hold moisture In brickwork and is probably penetrating roof level or anywhere the renders damaged .
The higher the damp the more moisture is being retained .

 

[Danrees]

I have checked the render over and cannot see any damage / cracks etc - will double check again.

 

[mrrusty]

The house has been empty for 6 months (no heating etc). I’m assuming this hasn’t helped things

No. Unheated, unlived-in houses degrade. One of the reasons is the thermal mass of the house. When it gets really cold, it takes a while to heat up again. If we have a weather change from freezing to suddenly warm and rainy, as we often do in the UK, the fabric of the still-cold house will be well below the dew point (dew is called dew because this is exactly how it forms) of the warmer high humidity air and huge amounts of condensation will occur if that air can get in to the house.

Once the walls are damp, the actual process of evaporation and drying has a cooling effect exacerbating the situation. Lack of ventilation slows the drying process. Over time, walls get damp and grow mould. If there are any hygroscopic salts hanging around they contribute to retaining dampness too.

 

[Danrees]

Thanks for all the posts so far. I need to get some heat in there - would a dehumidifier help also?

I’ve attached some more pictures of the gable end and front of the house. I have noticed that when there is heavy rain, the floor and hearth get wet also.