Blackjack on House Roof

Section62

Bendy_House said:

There must be a specific reason why they say 'not suitable for roof tiles', and I doubt it's that it won't adhere or seal a crack on there - it'll be something else, like they know it's not suitable for covering what will be moving panels, or there don't even want you to try and seal around the tiles which would stop natural ventilation. It's one of these comments that 'doesn't make sense' on its own!

I cannot think of anything this stuff won't stick to.

On a basic level, I suspect it is because it isn't formulated for that purpose, will look awful, and once applied will be impossible to remove.  Any sensible manufacturer is going to cover their backsides and firmly discourage a use that could see them being sued for the cost of a total re-roof.

Technically, bituminous materials degrade through the evaporation of volatiles - which ultimately leads to increased hardness and cracking.  Used as a DPM below ground level or covered over, the rate of evaporation will be controlled and slow leading to a reasonably good working life.

Applied to porous concrete or clay tiles on a roof - and baked in Summer sunshine - the rate of degradation will be faster. Leading to failure in a relatively short period of time.

Hence my suggestion that a bituminous coating or paint ideally should only be used as a 'nuclear' option with the intention to do a permanent roof replacement within the next year or so.

paperclap

Thanks both. I'll have a look into it further.

Let's hope the silicone has done the trick, so we can reroof next summer!