I'm self building a porch, have done some bricklaying in the past but very much a keen amateur ! I've made the mistake of not gauging DOWN from DPC top level so when I checked my levels after raking back 3 courses of first corner i found my top level was going to be short by 10mm, can I make up the 10mm over the next 2 courses by increasing my bed to 15mm or should I start again and get 1st course right and have 10mm beds all the way up (5 sourses). Unfortunately it has all set cos I had to leave it and only checked levels today..... lesson learnt !!!