Best method for internal wiring in timber frame walls?

Snag with this is the damp membrane behind the plasterboard.

Yes, the possible damage there would take some avoiding. The trip beneath the floor boards to the garage and back is only a maximum of thirty metres, so I think I'll go for that one.

I've run network cables through the roof space and just let them hang down through holes in the corner of the ceiling. The only one that goes downstairs is below the airing cupboard (where the cable modem, router and WAP live) and comes through the ceiling in a corner above the TV/Video/HiFi. If I was going to do it properly I'd go for the third of your options and run everything under the floor (downstairs at least).

I like the roofspace idea but I'd rather have the cables coming up a short distance from the floor, rather than a long way down from the ceiling. I think lots of exposed wires looks delightfully techie but I can't seem to convince my wife of it. The underfloor option would be more appealing if I could find a non-destructive way of lifting tongue and groove floorboards. I'm going to do it that way though, especially as you agree it's a good idea.:-)

I don't think there really is a non-destructive method - even if you remove the skirting board you won't necessarily be able to prise up a floorboard without marking or splitting it. I suspect careful use of a floorboard saw is the best compromise (along with choosing to cut boards that won't be particularly visible, but if your floors are like mine with the joists supported on dwarf walls you might need to lift boards in several places in each room).

I have a fairly modern house with good insulation but I've noticed that when those tongues get chopped there's a fair old breeze wafting through. Still, I can papier macho my way out of that one. I don't have dwarf walls supporting the floor joists here though I am developing an endwarfed appetite for hard graft. But hi-ho, what the heck, up come the fitted carpets, with floor sander at the ready for the finale.

Some minitrunking running down in the corner of the room, or behind flor-length curtains, can be quite inconspicuous once painted.

If you don't need access right along the floor void (ie you have a gap between the floor joists and the solum) you could use those cut-a-hole-in-floor-and-make-a-hatch templates (from Trend?)

Owain

Thanks, I'll have a look at those.