Depending on the color your going with on the exterior, if you keep it red or another darker toned color, I'd go lighter almost honey on the floors; knotty pine? I have always wanted to redo a barn into a modern/rustic home!

Do you want to keep the wood floor? It is rare to see wood floors as garage floors. I've seen homes like this moved onto pour basement slabs (same concept as pile foundation...but with a basement instead of dirt. If you want to keep the wood, then there has to be a way to keep the wood off of the concrete. An 18" crawl space (dirt covered with 6mil poly sheeting or cement) is always an option. The 18" crawl space would have to be cross vented/heated properly. This is for "keeping" the wood. Flooring. I'm not sure what has to be done to remove the wood floor and have the building sit (joists and all) on concrete. Remove the joists and you have plenty of stability problems. You would need to speak with a local architect/building engineer who has some knowledge of what you are trying to do, soil conditions, etc. to get this right. In theory it can be done (we've just landed a small car on a comet...we should be able to put an old building on a cement slab)...I'm wondering about the expense to get it there (excavation + soil stabilization + concrete + piles, etc).

Thanks :) Yeah decided to go with tile. So sand cement is ok over existing tiles if I prep them first? Only problem is, the new pad can only be about 30mm at it's thickest (leaving up to 15mm for tiles) otherwise it'll end up being higher than the hallway floor. So I either need to make the fall shallower or not bother with the waste and make it all level. If I made it level, could I use levelling compound at that thickness or would deck mud/sand cement be the best option? Also, should I be putting in mesh for strength? (I know I should (and will) ask the local hardware what they suggest, but it's great to have suggestions from the Houzz community also)

What kind of flooring alternatives are you looking for?