Debris left between slates and membrane

[Debzf]

Hi and thanks in advance, am in the process of having my roof done and velux windows fitted. It’s a house from the 1930 so the roofers have removed the slates and fitted a membrane as there wasn’t one before and the old cement was falling into loft. They have started to put the slates back on now but when I go into the loft there is loads of debris trapped between the new membrane and the slates they have put back on.. will this cause problems in the future
Thanks for any help

 

[catlad]

Its meant to be clear to aid drainage. Dock them some money.

 

[kp00110]

stuff like this bugs me, just being lazy and out of sight out of mind - for them atleast!

 

[robinbanks]

Or when they get their steel and slate axe and shave a slate or 10 down for valley cuts, then dump all the shrapnel onto the felt and it disappears to find a new home just above where the felt support tray shallows out the slope, waiting for a bit of wind rattle to encourage those glass sharp fragments through the membrane..