Hi, I'm thinking of reversing the garage conversion on my house because i'm desperate for a garage. As i understand it the garage floor will have to be dug out(concrete) because there needs to be a step down from the house connecting door, in case the car in the garage leaks fuel. Any information will help.
Yes you are correct, i believe there has to be an 100mm drop from the entry to the house and dont forget you will need a self-closing fire door also between the garage and the house. The seperating wall also needs to be a 'compartment' wall, but i suspect that if the space was originally a garage the wall itself should be ok.
If you Google "planningportal.gov.uk" and search for England and then professionals this may help you.
You will be able to download some info on the building regs required.
You don't necessarily have to have a 100mm step down from the dwelling into the garage. if the door is at the rear of the garage then the floor can fall away to the front of the garage OR the door opening should be positioned 100mm above the garage floor - thus a 100mm threshold can do the job (like a bulkhead door on a ship)
Friend of mine has a garage which has two steps DOWN into his utility which leads to his kitchen.
When BC came along to inspect his extension they noticed this and said that it was clearly impractcable to have a step down into the garage. The suggested that he have an additional step up (imagaine a small lintel laid across the doorway) so that a step down into the garage resulted.
Your local LBAC may allow you the same latitude which would avoid having to dig up your concrete.