External wall insulation

Adding insulation and rendering to a damp wall will only increase your damp issues, Good luck Alex

Hiya, the only scenario where doing as you described would help a damp problem is when you either have cavity wall insulation and dampness is traveling through to you inside skin, or you have snots(clumps of mortar) on your wall ties in the cavity, or if the wall has no cavity. If this is the case then your cheapest option to try first is treat your external brick with thompsons water seal, you can do this yourself if you are fit and able and it will only cost you the time and materials. If it is rising damp insulating the outside would make the problem worse as moisture wouldn't be able to escape the bricks. In this case the best solution is to put a traditional damp course in where 3 to 4 bricks are taken out at a time and a new 125mm damp course is rolled out before adding bricks back in and moving along. I suspect doing both of these solutions would be less expensive than the external insulation and render AND extending your roof spars to cover it. Hope this helps.