I've known of several instances where hot runny asphalt has infiltrated fine gaps in roof coverings, sometimes travelling some distance through horizontal unconformities, and dripped into rooms and corridors below. Therefore, unless there is certainty that the roofs being worked on are impervious, it's appropriate to consider arrangements to prevent drips from landing on people below. The instances I knew involved relatively small drips inside flat-roofed schools where it wasn't always feasible for roof repair/replacement projects to be carried out during school holiday periods. Fortunately none of the drips landed on staff and pupils or their clothing, etc., so the schools and my local authority employer were spared the considerable hassle and cost of dealing with such circumstances. Even so, the thought of having to do prompted the building services department to ensure that there was good regular liaison between roofing contractors and school managements to try and exclude employees and pupils from indoor areas below AND near where hot work was being done. Also, sometimes plastic sheets were spread over floors and furniture, etc. to protect them from hot drips. Also, while visiting various hot work projects on school roofs over the years I was relieved to see that the contractors involved usually took considerable care to ensure that inquisitive pupils and others were kept well away (e.g. by use of Heras-type fencing) from areas where tar boilers were in use and also from the ladders, etc. used to provide temporary access onto the roofs.

SLR24 To be honest I can't remember much about precautions provided to enable roof workers to deal with fire if it occurred while they were on the roofs. Also, I can't recall being aware of instances of fire occurring. This might have been due to not being told of instances, or perhaps good luck and/or observance by contractors of reasonable working systems and precautions to prevent fire. Hopefully, other more knowledgeable forum users will respond about fire precautions for hot roof work.

How are they getting the cylinder and / or bucket of molten pitch onto the roof? I wouldn't want either carried up a ladder... and even a fixed pulley arrangement isn't foolproof for buckets of hot stuff - as one guy I had to take to hospital several years ago would have testified. (I mistyped that first time around and put 'hod pital'. Serendipitous typos always make me smile). And make sure there is an adequate fire watch after the end of work... at least forty minutes, and preferably an hour. There can be a long time between initial hot contact with fuel and fuel starting to combust

Thanks for the replies we don't actually take the propane cylinders up on the roof. We keep these at ground level and have the hose and torch on the flat roofs. we are only burning the adhesive bitumen on 300 x 300 pads to secure these to the roof so we would burn the bottom of the pad and the section of the roof and then place the pad on that section. This would then form a firm bond between the two. I haven't considered an alternative, but the pads need to be burnt to fix on, not sure what adhesive would be as strong as the bond when it is melted on ?