DIY BISF BISF EWI ventilation requirements
Firstly I would like to say what a fantastic website this is and it has been invaluable in helping with information and help needed for upgrading my BISF house.
I have been lucky enough to secure a Green Homes Grant to contribute towards installing EWI to the original exterior. However after no end of problems and countless delays I was then informed I needed a retrofit ventilation survey before any work can be started.
A retrofit assessor viewed my property yesterday and informed me he had only qualified the week before and wasn't aware of BISF houses, hence resulting in myself explaining to him how it was constructed.
I have already been informed I will need a kitchen/bathroom extractor fan fitted however he also mentioned trickle vents possibly being installed in the existing double glazed windows and further possible vents in the walls themselves.
Obviously I would rather not be hacking into perfectly sound windows or installing extra vents if not needed let alone the extra cost this will entail.
Am I right in thinking the ventilation void between the exterior and interior walls would be sufficient enough ventilation for the EWI to be installed without any further measures needed? Any information would be greatly appreciated!