High damp readings in internal walls

stuart45

If a single storey extension has been added, it's still possible for water to enter the cavity if a cavity tray wasn't installed in the wall at the roof /wall junction. However this normally shows up at a higher level as well.
To clear a cavity you normally take out a small amount of brickwork at each end and take out the odd brick along the course as coring holes.
Then get something like a piece of roofing batten with a nail in the end and rake back the debris to the coring holes and remove it.

Mistral001

sgjfrods wrote: »

Thank you. I think the camera idea seems like the less destructive option. I will take a look and see.
One point to note though the wall where the damp joists run into isn't an external wall. It used to be the back wall of the house but an extension got added and therefore its now an internal wall.
I suppose damp can rise through the filled cavity and up into the joists from there though, it doesn't have to come from driving rain?
Also lets say the cavity is full of debris above the DPC, how on earth do you clear it along the length of the wall?

Is the extension single storey and the cavity wall two storey? If this is the case then there would still be a path for water to get in to the cavity from above.

sgjfrods

Yes the extension is single story and the cavity wall is double story.