leaking or trapped moisture?

[mushers]

hello all
im having a few issues at the moment with water ingress into my conservatory its a lean to style with single block walls
some months ago i noticed some blowing of paint with plaster salts behind at the top of the left wall which is block with dot and dab plasterboard
when i bought this house the conservatory was newish but.. the external walls where bare breeze block which i have had rendered 9 months is ago
at first i thought the damp could be trapped moisture from when the blocks wear left open to the elements trying to escape and thought i would look into it later
recently my lighting in the conservatory went POP during sunday lunch after a few tests it was clear there was a break in the cable so pulled up my floor ran some new cables ect and thought time to tackle the damp wall while im making a mess
the lead looks fine however the coping stones im not sure about some have a fine green line in the morter joints and one is nearly loose could this be the cause ? should ther not be something under them to stop this happening other than the lead which looks like it starts halfway from the blocks then down to the roof
or could it just be trapped moisture?

 

[mushers]

pulled off the stones at the top today some were loose lots of bugs living in the morter joints and water underneath so i guess it was leaking

 

[freddiemercurystwin]

Photos will help as would a simplified first post.

 

[jadzy]

Didn't think copings were supposed to prevent water ingress, just provide an overhang to protect the face of the wall. A DPC under the copings provides the barrier to stop water coming down through the wall.

 

[noseall]

I really do not like parapet walls, they can be a nightmare.

As said, there should be a dpc running the entire thickness of masonry to prevent downward travel of any water.

 

[cotswoldbuilders]

Dot and Dab on a single skin wall isnt any good, damps going to travel through.

 

[mushers]

Didn't think copings were supposed to prevent water ingress, just provide an overhang to protect the face of the wall. A DPC under the copings provides the barrier to stop water coming down through the wall.

just lead covering half the block and stones on top
pulled of the loose ones yesterday cleaned em up stuck em down again
they were wet underneath around the poor morter joints dont have the time at the moment to do all with dpc hoping this will hold untill better weather comes along

 

[mathewleo]

It seems to be a moisture. But if you can send the pictures the it would be a great help.

 

[mushers]

It seems to be a moisture. But if you can send the pictures the it would be a great help.

not much point taking pictures right now
coping stones have been stuck and pointed and plaster board removed around the damp patches blocks still the wrond shade of grey