Drilling through a timber-framed exterior wall

[miff_mole]

Hi,

I'm a bit of a newbie at all this, so apologies in advance if there is anything stupid or obvious about my question !

Anyway, we have a 1960s timber-framed house. The side walls are brick,
where as the front and back are not. They are relatively thin with cladding on the outside and plaster on the inside (not sure what you call this type of wall - can someone enlighten me !?).

We are planning to have exterior security lights installed which will mean that we will need to drill through the front and back walls to run cables through.

My question is, what are the issues when drilling through this type of wall ?
I gather that this type of wall usually has a vertical damp-proof membrane in the middle of it, so what do we need to do if we are drilling through this?

Any advice most welcome,

Cheers,

Miff,
Oxford, UK

[Perry525]

The integrity of the wall relies on a relatively damp proof membrane installed on the inside of the wall, to stop the excess water vapour in the air entering the wall and rotting the wood.
And a similar plastic waterproof membrane under the cladding to keep out the rain.
If you breach these membranes and do not make them water vapour proof, then the interior of the wall may become wet with condensation and start to rot.
I would suggest that you consider mounting these lights at the top of the wall and under the roof overhang, they will cause more light pollution, for the short time they may be on but, your walls will be safe.