Hi, I have a reasonable size 2 storey detached house in which I rent out up to five bedrooms (currently four as I am not licensed under the new rules) to individual tenants who share everything else, i.e. kitchen, bathroom, toilets, fridge, freezer, etc. There are seven exit points - four downstairs including three doors and one opener, i.e. one in every risk room, and three through window openers at the front of the house that give access to ground floor flat roof areas. I need to put in fire doors and would like to fit 35mm ones into the existing sound frames as advised by various experienced local fitters. This would be far less disruptive than removing the existing sound frames and replacing with the slightly thicker certified frames. I could fill any gaps between the wall and the frame with intumescent foam and put strips and smoke seals on the door and/or frame. I think this is reasonable given all the escape routes and the fact that it is only 2 storeys, together with the fact that they are all able-bodied working/professional people who would be able to exit in about 2 minutes rather than a six storey block of self-contained bedsits with only one exit route and possibly people with impaired mobility. However, the Housing Officer is insistent that I need to have everything certified to 30 minutes. As I understand it, the LACORS guidance is precisely that and advises that whilst this is an ideal situation, each place should be taken on its own merits and excessive measures should not be required, e.g. a 3 storey HMO might do with 20 minutes protection in practice. He claims that it is a "classic bedsit HMO" that requires an absolute minimum of 30 minute certification for doors, frames and fitting rather than taking reasonable measures, which seems excessive and unnecessarily destructive. Can anyone help me on this please?