flue exiting on a wall beneath flat roof

7 Nov 2008
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Mid Glamorgan
United Kingdom
I am considering all my options for flue positioning on my single story flat roofed kitchen extension. i would like the boiler on the kitchen wall as high as possible above the worktop. this in turn wuld mean a horizontally exiting flue will also have too exit higher on the outside wall.

building regs state that flue needs to be min distance below eves ie 300mm for balanced flue with natural draught, 200mm below for fanned draught. My questions are;
Does rule also apply to the edge of the roof covering on a flat roof ie does the flue have to be a min distance beneath the facia board (no drain pipe of guttering attached). If so is it the same as for eves?

Does most new combi boilers have fan assistance built in to aid waste gas venting? Meaning that if a min distance from the facia board doed apply then I can get away with 200mm.

If I dont have sufficient distance beneath the facia board is it acceptable to have a 90ish degree bend t take the flue above roof height?

another option to consider is going vertically up through the ceiling . in which case the flue pipe would be partially enclosed in the space between the ceiling and roof. Does this mean an inspection hatch is needed for this short length wi9th no joints?

the roof covering is fibreglass. can the flat roof flashing kits used for bitchumen roofs be used with fibreglasss.

thank you for reading this post and hoping you can help with these questions
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