vent stud wall or not after tanking

[habilis]

Hi

We had some damp in a rear extension bathroom. Caused by an outside ledge where old party wall butts up against extension letting in water, slightly raised ground level and brickwork next door, old flat roof amongst other things!!

We have hacked off all damp render back to bricks, had dpc injected above level of outside bridging and wall tanked with cementitious slurry. After this our builders have put in a stud wall, all lined with damp proof membrane between timber and wall and then put in xtratherm foil-backed insulation between studs, leaving a cavity and plastering over.

My question is do we need passive vents in the stud wall? The builders were advised to leave small gaps at top and bottom of xtratherm insulation, which they did before plastering over.

 

[RoughWaters]

Worked on a listed building where a whole team of experts came up with the same solution. The said so long as their were gaps top and bottom it would 'breathe' .

 

[habilis]

thanks for replying -so it will breathe through the plaster without vents?

 

[RoughWaters]

apparently so. Guess not if you use foil backs though I have worked on many jobs where the walls are studded - cellotex and boarded/skimmed. So long as you have taken measures to stop water ingress at source it will be fine. All the origional houses in my area are stone. This leads people to do as you have done over the whole house in some cases. So long as its watertight from the outside in vapour wont be an issue.
Just make sure the wall has dried out enough before you close it back.