'Non-setting mastic' is sometimes recommended for pointing ridge tiles as an
alternative to sand/cement, to allow for slight movement.. However, I don't
know where to find it - the only non-setting mastic I can find is Plumbers'
Mate - obviously unsuitable!

There are plenty of low modulus building mastics but they are not
'non-setting'. Can anyone suggest where I can get a suitable non-setting
mastic?

Thanks