Might have been covered before but I couldnt find it. I have an old shed which is not in great condition, however it does have 75% of the floor concreted. Can anyone advise on the rules for replacing a shed? It is 90 x 100ft with steel uprights, internal telegraph poles, and a glorifed tin roof with brick walls and concreted in feeders. I would like to replace with a 90 x 60 which covers the existing concrete, but also raise the height by three or four feet. Is that a full PP job, or are there rules for replacing something that has done its time? Ideally I would like to avoid using my PD as I want that for something else. Existing shed is probably 60+ years old and the ventilation is not up to modern cattle spec.