Retro fitting trickle vents

darich

Hi

I’m considering fitting trickle vents to my patio doors which currently do not have any ventilation system.
I’ve been reading up on it and fitting them doesn’t scare me but I’m unsure on a couple of things.

When drilling the door to fit them, should I drill through the metal reinforcement? Or is it sufficient to drill through the plastic?

And I’m guessing the holes on the inside would be better if they were offset from the holes on the outside to reduce the possibility of a through draught? I think if I drilled from one side straight through and out the other side, the draught and noise would be increased.

 

Thanks