twin walls/fire stops help

[joe brown]

I was working at a house today when a nieghbour popped round asking for some advise, he has had a room sealed woscester bosch with vertical flue, im only cold water at the moment so dont know much but he asked me if he needs a firestop going through the roof and stated that the plumber insists he doesnt need one as he has twin wall flue ? i couldnt answer him but any guidence would be appreceated

 

[lame plumber]

two things first any flue going through combustable materials must be protected to stop possible damage to wood etc its near, hence use of firestops etc. definitely need one for single skin cant remember for twin wall. Second issue is fire/smoke integrity, any hole cut through walls ceilings breaks the fire break caused by the hole so you should reseal it with a approved fire stop to prevent the leakage of smoke and flame.

You may not need it for first reason but should do for the second to meet building regs reqs, and a lick of sanitary silicone round the hole isnt deemed enough to give a 30 min barrier!!. call building regs in your area and theyll quote a definative answer as far as they are concerned

 

[GrahamM]

As above. If the flue goes through a ceiling the gap round the flue needs to be made good to keep the fireproof integrity.

 

[stevetheplumber]

fire regs are different depending on the buildign single dwellings under three stories are generally dont need fire stops multiplle dwellings of any size do

 

[AWheating]

as general rule is you need to keep the fire integrity of the wall or ceiling your going through. the flue normally comes with a metal plate or get some supalux and make one. the flue should not touch combustable material which includes plasterboard.