Install log burner in timber summerhouse

Hi guys, this is a new one on me! I have been scouring but cant find a definitive answer that will allow it to be done at all.

I need to install a stove in a timber construction summerhouse. The floor is timber with concrete slab under & i know this timber must be cut out & constuctional hearth built up to regs. The roof is pitched tongue & groove (vaulted celing) with green mineral felt covering plus a later added metal roof on top. The main problem i have is obvoiusly distance from flue to combustible materials! I believe this needs to be 500mm. Any suggestions for going through the roof boards, bearing in mind the distance from the ridge beam to purlin is 760mm and from purlin to top of wall is 990mm.

From recent correspondence I think 500 mm is too much. You should check : lots of threads on stoves with attached regs on here.

A major point will be if it single-skinned or double-skinned flue.

Yes, flue will need to be twin wall, so i believe 50mm to combustable material! 450mm for single skin flue. Also believe the decorative hearth can be 12mm without need for constructional base, as long as the stove base temp does not exceed 100 degrees C. Tell me if im wrong!

Good calculation, did it work out?