@Avanya: cracking; I'll give it a go...

@starshall96: Yes. In object mode press ctrl + A and then select "Rotation and scale". Then it should export mirrored. It's generally a good idea to do before exporting anything, so that the scale and rotation is as expected. :)

@ Avanya, I'm tyring to create a mirror image of this asset - but for the life of me i cannot get it to import to untiy correctly. I've mirrored the asset in blender fine, but for some reason it reverts to the "old" orientation in asset editor. Any ideas?

@ Kombat Wombat - yes, it is a bit "fire-stationey" - I think its the doors that do it. I may well take up your suggestion and do a conversion in the near future.

Nice :D

Nice building, just a thought, if you added a second garage door, and a couple windows to either side you would have a ready-made fire station.