Please can anyone advise if the position of the core hole in the attached pic is a problem? It's for an extractor fan and I was tight for space on the internal wall, but didn't mean to get so close to the lintel! The timber lintel you can see is only supporting a course of blocks so no worries there. But I'm less sure about the concrete lintel on the inner skin, which will be carrying the weight of the roof trusses above. I think it has a similar bearing to the timber lintel you can see (about 100mm). A stupid thing to have done I know but i'd like to know just how stupid, and whether I can stop worrying about it. Thanks.