Perimeter noggins - Same size as joists?

[denso13]

BTW - why use PVC channels over steel? Surely the idea is to less easily drill into wires?

It's just for basic protection, like a plasterer's trowel, nothing more.

 

[cdbe]

The wall boards or plaster will support the ends of the ceiling boards - you don't need bits of wood.

 

[AFT4B]

The wall boards or plaster will support the ends of the ceiling boards - you don't need bits of wood.

I did have that thought too, to be honest.

But it's generally recommended so...

 

[robinbanks]

My understanding is that it's just for additional support for plasterboards?

I don't bother; put the ceiling boards up first then butt the wall boards up to them with a line of adhesive along the joint. Ceiling board can't sag if it's resting on a wall board

One of these makes it easy to butt the board up while you get a few screws into it;

I'm now thinking cables in steel channels and pipes

Absolutely not. We haven't done that for at least 60 years. Ensuring the conduits are all properly earthed is such a massive pain in the arse, and so likely to fail, that it becomes a massive danger to have large sections of your conduits become live by one carelessly driven screw bridging from live core to conduit

The professional electrician that you employ to do your wiring will never, ever run residential cabling inside metal conduit - they'll use RCD protection and bury wires to the recommended depth.

That you're floating the idea makes me gravely concerned that you're considering doing your electrics yourself and that you're asking the question indicates you're not what the law would call a "competent person" (i.e. properly electrically trained)

 

[AFT4B]

I don't bother; put the ceiling boards up first then butt the wall boards up to them with a line of adhesive along the joint. Ceiling board can't sag if it's resting on a wall board

One of these makes it easy to butt the board up while you get a few screws into it;
View attachment 403021


Absolutely not. We haven't done that for at least 60 years. Ensuring the conduits are all properly earthed is such a massive pain in the arse, and so likely to fail, that it becomes a massive danger to have large sections of your conduits become live by one carelessly driven screw bridging from live core to conduit

The professional electrician that you employ to do your wiring will never, ever run residential cabling inside metal conduit - they'll use RCD protection and bury wires to the recommended depth.

That you're floating the idea makes me gravely concerned that you're considering doing your electrics yourself and that you're asking the question indicates you're not what the law would call a "competent person" (i.e. properly electrically trained)

Thanks for the concern but I have no intention of doing electrics (or plumbing) myself. Not least for insurance purposes - in that, should anything go wrong, I would need to prove it's been done by a competent person to validate any claim (it will be obvious the wiring is recent). But also because I am not qualified to do it.

What I AM doing however is a small amount of chasing for wires etc to get a good finish/ not too much wall build-up and so I can put stud walls in, etc. The electricians I have spoken to have all said they normally just pin the wires to the wall if walls are being D&D'd.

We're also having a new fuse board with RCBOs throughout the house as part of a complete rewire so there is "protection" there should someone drill into a wire.

But the bit I have struggled to get my head around is why there isn't something to stop you being able to drill into a wire in the first place? Because whilst RCBO will ensure nobody gets hurt - you've got to rip out the wire and redo all the good work again.

 

[robinbanks]

But the bit I have struggled to get my head around is why there isn't something to stop you being able to drill into a wire in the first place? Because whilst RCBO will ensure nobody gets hurt - you've got to rip out the wire and redo all the good work again.

There is;

Burying a wire 50mm into a wall puts it reasonably out of the range of most drill bits used for casual item hanging like shelves or pictures/ornaments, with only more major stuff like adjustable arm TV brackets etc truly requiring bigger fixing..

But more critically it's a rule that the area of wall directly above a visible accessory like a socket or switch and the area of wall horizontally extending from it, plus the areas of wall 6 inches away from where two walls meet to form a corner, or a wall and ceiling meet, are designated safe zones for wiring; wires shall always and only ever be run in these zones. Anyone drilling into the zone accepts the risk of hitting the wire and the subsequent costs of repair. Ceiling wires may run anywhere but decent sparks seek to keep to the 50mm depth rule by clipping the wires to the tops of joists deeper than 50mm. Ceiling cables are usually more free to move and if poked with a drill even if they are in direct contact with the plasterboard, will move out of the way and are less likely to be damaged. The presence of switches and sockets on a wall is one reason why, when taking a switch out of use, we don't just joint the wires and plaster over the back box, hiding it; its presence defines and describes the safe zone and a blanking plate should be used so people can still see "in that 4 inches of wall there and there there could be a wire

If some dipstick has run wires diagonally all over, and you hit one when drilling where the wall is supposed to be ok to drill, you do really need to rip that diagonal wire out anyway and re run it in a safe zone

See for diagrams:

https://www.diynot.com/wiki/Electrics:walls

In terms of how I construct walls now, for internal walls with 4x2 studding the 50mm rule is easy to adhere to by drilling stud centres, and wires are still run as per the zone rules. For walls like external ones, or ones where it's timber sidewalk fully filled with rigid insulation i do prefer to form a service void for pipes and wires by battening the wall out to introduce a 25mm space between the plasterboard and the wall. As this is a space where wires can hang loose I can get away with drilling in safe zones so long as I carefully drill only the plasterboard, then check there isn't a wire directly behind, move it to one side if there is, and drill again. Having the flexibility to move the wires is a major plus that is lost if they're plastered in, but I do also accept that some people may prefer not to lose an inch off their room