I guess I ought to have posted
this on this thread....
Your post reminded me of an similar incident while I was replacing some rotten floorboards prior to a laminate floor. I was showing the customer the rotten boards and explaining why I needed to replace them . She then casually flicked her cigarette end onto the floor- i said jokingly that could cause a fire and she laughed it off saying the insurance would pay for her new floor. anyway work continued and every now and again I thought I could smell smoke -quick check revealed nothing, couple of hours later and same again- checks showed nothing wrong so carried on and went for lunch . Back on the job and again the odd whiff of smoke, so checked all my tools and nothing evident- I’m using a circular saw to cut through what is left of the boards so a slight smell of burning is not uncommon as I used an old blade due to nails , grit etc in the t/grooves but my 3 rd sense was niggling away-then I remember the earlier cigarette

- up came the boards previously replaced and there it was -the floor was suspended and 1/2 ton of rubbish below was glowing and smouldering away like a furnace-no flames just a mass of debris glowing, within 60 seconds ( fresh oxygen I suppose) up it went flames 2-3 ft high-and then came the adrenaline and shock and panic all at the same time, cust upstairs with her 6 months old baby ,, grabbed a nearby hose I’d used earlier to wash down and with the phone in one hand dialing 999 and shouting the cust to get her baby and herself out started spraying water like a madman, half the floor was ablaze and I was out of my depth - just as I was getting it under control flames would pop up in another area - finally the f brigade turned up and got it under control, I knew the customer and her child was safe outside but although it was her fault I felt responsible. I found out later that sawdust had been put under the floor to insulate and protect against damp but it was bone dry and one cigarette butt that must have found it’s way under the floor while the boards and slowly built up enough heat that when I eventually removed the boards in went the fresh oxygen and up it went , I often think what if ??