bedroom wall damp - still working on it

[thursdaycat]

Hello again

After my post last month about my damp bedroom wall, some small progress has been made but I need advice again now.

We now know the damp in the bedroom wall is not coming through from any problem with the roof (flashing, tiling or felt) so have decided it must be either porous stone or defective pointing or both.

This is a picture of the wall from inside:

As you can see, 2 areas (the ones which look dark) have been patched before. Builder no6 (don't ask..) explained that the reason the damp is coming through on only these 2 patches again is that the plaster is blown on the whole of the rest of the wall so behind that plaster the water can just flow around - ie it only comes out in these 2 patches b/c these are the only 2 bits where there is anything bonded to the wall.

He thinks I have 2 options now:

1 Ignore it. Cover the patches with damp seal first to seal the stain then decorate over it and accept that there justis a damp wall. It doesn't seem to be creating any other problems (apart from spoiling the decorations).

2 Hack off the plaster in a strip from floor to ceiling on this left side of the window. Leave it exposed and hope that it becomes obvious next time it rains a lot where the water is coming through. Then point that area on the outside (not sure what to do if it's porous stone) and replaster inside with something he called "renovating plaster".

I am minded to option one, my husband prefers option 2. I am concerned with option 2 that we will take off a section of plaster, still not find an obvious cause, then have an even bigger area of now bonded plaster to show the damp in future.

Outside access to the wall is difficult and will involve scaffolding so there's no easy option to get up a ladder and check the pointing in detail - all we can say is that from ground level there's nothing obviously wrong.

Any advice on how to proceed from here?

Many thanks again

PS I finally learnt how to use photobucket!

 

[middi]

Unless you find out the reason " why", you will be guessing as to how the problem can be cured.

I can understand you want to just get it over and done, but, option two is the best approach, also you have no choise but to inspect closely the condition of the external wall face, the window cill condition, pointing or any delaminating effect in the actual stones.

 

[L1zzy]

I agree - I know its tough but better by far to spend money on Option2 and begin at least to get to the root cause of the problem than continue to speculate. I too have a damp bedroom wall its the gable end that is also home to the chimney - I lie in bed thinking I wonder what the cause is.... and am gradually resigning myself to the fact that hacking all the grotty concrete off the outside repointing with Lime is the ONLY solution. Best to accept this and move on is my own view.Good Luck

 

[Moo]

Your builder seems to be thinking along the right lines with option 2
EXCEPT for the suggestion of using 'renovating plaster'. which sounds rather sinister.

 

[NT]

What makes you think water is coming through from the outside? Condensation is more often the issue.

If it is coming through, 'sealing' the interior is not a great option, and renovating plaster is the wrong stuff to use. I would not therefore want to rely on your builders advice.

And re porous stone, lots of buildings are made from it, and dont suffer damp problems. Rain soaks into the surface, and evaported out again afterwards. Rinse and repeat ad infinitum quite happily.

Have you read the damp faq? It should be considered a first draught, not the final say, but theres a fair bit of info there.


NT

 

[Nemesis]

What was he intending to repoint with?

 

[AMc]

Can you use binoculars/digital camera with zoom/camcorder with zoom to get a better look at the problem outside from ground level or a neighbours window?

I have recently been using my digital camera to take pictures of my leaky roof. I have a mystery velux fitted in the loft, but the angle means I can't get my head out when it's open or up to the glass when it's shut - I can however get my arm out. Put the camera on a variety of zoom settings, hold it out the window and press the shutter repeatedly. Go back to my warm office and examine the shoddy flashing in the gutter with a nice cup of coffee.

 

[Nemesis]

I have a Canon Powershot with a screen which can be moved. Very useful for these sort of situations!

 

[plumbers mate]

Secure the camera to your wrist or to a bit of rope tied inside the building before waving it about in an inaccessible place - a scratched camera is better than one stuck out in a gutter.

 

[thursdaycat]

Amc - thanks for the suggestion - it really hadn't occured to me to try binoculars. I will try that and see if an obvious fault shows up.

NT - why water from outside? well isn't that position just left and to the side of the window a rather place for condensation?? the builder did mention that possibilty but too actually but didn't seem keen on it as an explanation. the damp stain that I had on teh wallpaper just seemed too big for condensation and it was right where that dark patch of previously-patched sand and cement is. unless you think otherwise?

is there any way to test if it's a condensation problem??

 

[Lime]

The damp patch below the window line is almost certainly being caused by water coming off the window sill and running into the wall rather than dripping off the sill.
Assuming you can open the window, on the outside look at the bottom of the sill underneath to see if there is damage apparent either structurally or by water/frost.

 

[BMcD]

thursdaycat wrote:

the damp stain that I had on teh wallpaper just seemed too big for condensation and it was right where that dark patch of previously-patched sand and cement is. unless you think otherwise?

Just a thought. If the damp patch is where sand and cement patching is and the rest of the plaster is sand/lime or de-bonded then perhaps condensation is possible as will not the sand cement retain moisture where sand/lime will allow it to evaporate therefore making the sand/cement colder and more likely as an area for condensation to form? Like wise if the surrounding plaster is de-bonded will an insulating air gap not have formed behind it, then moisture again will be more likely to condensate on the colder sand/cement?

 

[thursdaycat]

well I think I like the idea of condensation being the cause best as this seems easier to fix (right? by providing more ventilation?)

so.. is the next step to ventilate more and see if it dries up? will that prove if it's condensation or not?