Another bubbling & flaking plaster/paint question!

I have an interior wall which on the other side is the back passage/entrance for the house.

http://www.flickr.com/photos/98549025@N05/10189600876/in/set-72157636393178975

http://www.flickr.com/photos/98549025@N05/10189601966/in/set-72157636393178975

The paint on the wall was flaking and bubbling quite badly (see pic) which I assume was caused by damp? Is this the most logical reason?

http://www.flickr.com/photos/98549025@N05/10189614236/in/set-72157636393178975

http://www.flickr.com/photos/98549025@N05/10189471944/in/set-72157636393178975/

I have since sanded down the flaking/bubbling, and filled the minor holes with just normal filler rather than plaster, since doing this the filler in places also bubble up in a similar way to the previous painted surface (n.b I was going to paint over the section with damp seal but wanted to get to the root of the issue first)

http://www.flickr.com/photos/98549025@N05/10189609056/in/set-72157636393178975/

Now with regards to the cause of this...on the exterior wall side there are a couple of things, firstly my Virgin Media cable box is drilled into this wall as well as hole to feed the TV wire:

http://www.flickr.com/photos/98549025@N05/10189655843/

And secondly i noticed that there two sections of the brickwork that were the cement is missing:

http://www.flickr.com/photos/98549025@N05/10189566635/in/photostream/

Is this possibly the main cause? I guess I should fill these two holes in as a matter of course?

Just to add that that same interior wall had a mould issue before too, which i think i resolved with Wykamol.

p.s. how do i link the images properly in the posts?

definitely fill those mortar joints for a start.

the inside pics look like rising damp.

are the walls cavity or solid 9inch?

how would water be ingressing from the passage? Driving rain seem unlikely but do you get pools of water down there if it's wet?

You need to firstly find the source of the water and then remedy it, maybe the DPC has failed and you need a new one retro-fitting, can be done with dryzone injected into the mortar joints.

Might be worth prising the skirting board away and check you haven't got gypsum plaster right to the floor. It can wick moisture up the plaster if it's in contact with the floor and no gap.
If this is the case, it won't be helping, but may not be the whole problem.

s79 said:

p.s. how do i link the images properly in the posts?

Click to expand...

The flickr links are ok, but it is possible to upload photos to an album on diy not and use them from there.

Many thanks for the replies, much appreciated.

I should point out that im a novice when comes to all things plastering/rendering, so bare with me!

But yes I will definitely fill the mortar joints asap. That part of the passage is expose to the elements (the only part that is) so i imagine rain water sits there for a while, as there does not seem to be any drainage.

Driving rain could also hit that part of the wall. Thinking about it now, those mortar joints are looking especially culpable!

Anyway silly novice question no.1) Will normal "cement" do for the mortar joints?

Silly novice question no.2) I did a quick google on dryzone, sounds like exactly what i need, is it simply a case of injecting it into those two mortar cracks and then cementing the mortar (as above). And does dryzone mean i don't need to retro fit new Damp Proof Course, or are they used in conjunction?

Silly novice question no.3) If i prise the skirting board off and the plaster does contact the floor (which is what i suspect) what does that mean in relation to the problem?

P.s. If it helps the property is a late 1800's terrace in Leicester, so its a shared passageway with the next door neighbors house.

1. normal cement and building sand mixed 4:1

2. dryzone is normally injected along a horizontal mortar bed in holes drilled through almost to the inside of the wall and spaced about 200mm apart done in the mortar bed where the DPC should/needs to be.

3. if gypsum goes to the floor the chisel an inch off and re-fix skirts