Subsidence repair crack where extension meets main building

Not knowing full extent of the drain failure etc but as there is internal cracking as well I would advice that you have the Helifix bars fitted to the inner wall as depending on roof pitch it is most likely the inner wall has a wall plate and therefore taking the roof load so will be more susceptible to movement due to the subsidence. I assume you had the problems assessed by a structural engineer and it was they who recommended the Helifix reinforcement ?? if their recommendation was to do remedial works to both inner and outer skins then you should carry out the works in full Regards David

Hi, I would agree with David. The inner skin is most likely to be the load bearing structure and therefore the most important. Have you had an engineer’s report for this work as this should specify the location of the bars? Crestmark Roofing and Construction