Thanks for your comments everyone, one side elevation is about 1.000m from the boundary so I could certainly argue for that elevation to be masonry on Building Reg's grounds. Current ridge height is 4.9 with eaves at 3m, his main grievance is that he thinks it will be over domineering upon the house if it's built out of the same brick, it's 1.2m from the house at the back corner but angles away so it's about 5m away by the front corner, he believes dark stained timber cladding will be less prominent. The house is 2 storey and house eaves are above the garage's eaves and likewise the ridge is higher, so I can't really see where he's coming from. It is semi rural, but not remote, last house on the lane before it goes into countryside and the front of the garage is over 20m from the road. Looks like it's just one of those cases where his opinion is different from mine and he's exploiting the fact that he's the Planner. I'd rather not have to delay with an appeal because I want to get building and as it's quite likely I'll be selling the house within the next couple of years I need to keep it legit. He's on holiday this week so I'll enter phase 2 of the negotiations next week, just hope he sees sense because it will be a real pain propping the roof and trying to build the walls up out of brick to meet it.