Running new cables behind plasterboard...

[vonsworld]

Hello

In my home there is one ring main that mostly runs under the floor upstairs, and then loops down behind the dot and dab plasterboard to each socket downstairs.

I'd like to extend the ring and add a socket in the kitchen. So I was wondering how easy it would be to patch into the ring upstairs with junction boxes and then loop a cable down behind the existing plasterboard to the new socket location downstairs.

If you lift the floorboards upstairs, it is usually possible to gain access to the cavity behind the dot/dab plasterboard downstairs?

Once the cable was pushed down behind the plasterboard, presumably I could find it downstairs using a cable detector and drill a hole to retrieve it?

Do you have any advice or tips please

Thanks
Robin

 

[Taylortwocities]

Good luck with getting cable down behind the plasterboard. If it’s dot and dab on to the wall there may not be a clear run from top to bottom. a set of cable rods is the best bet to get from A to B.
I have never found a cable detector that lives up to its name.

You can use junction boxes but note that they must be maintenance free if the junction is not accessible. One of these is a good bet
https://www.tlc-direct.co.uk/Products/ASJ803.html

If you just want to add one socket then just a spur will be ok. Then you only have to wriggle one cable down.

 

[EFLImpudence]

I'd like to extend the ring and add a socket in the kitchen. So I was wondering how easy it would be to patch into the ring upstairs with junction boxes and then loop a cable down behind the existing plasterboard to the new socket location downstairs.

If you only want one (single or double) socket , you don't need to extend the ring so just one junction box for a spur.
You will need a "Maintenance Free" JB.

If you lift the floorboards upstairs, it is usually possible to gain access to the cavity behind the dot/dab plasterboard downstairs?

No. The ceiling will be in the way.

Once the cable was pushed down behind the plasterboard, presumably I could find it downstairs using a cable detector and drill a hole to retrieve it?

The cable must be vertical from the socket so that will make it more difficult as, presumably, you will want the socket in a particular place - not just where the cable happens to be - and the dots will be all over the place.


You will have to start from the socket position and probe vertically, find the first dot in the way, channel the plasterboard and dot, then do the same from the new space to the next dot. When you reach the ceiling, drill up close to the brick work if necessary.

 

[AndyPRK]

If it’s just one outlet, spur it.

With my plasterboard there is a horizontal wooden batten just down from the ceiling and then one half way down the wall.

Therefore you will need to cut a channel for about 4” by the ceiling to find the wood. I then chiselled the wood to the depth of the cable.

You can then have a go with a rod down the back of the plaster board.

Cut out your socket. Tap the area to ensure it sounds hollow first.

Depending how well the p board has been fitted you may need another hole or you may need many to get the cable top to bottom

 

[JohnW2]

If you lift the floorboards upstairs, it is usually possible to gain access to the cavity behind the dot/dab plasterboard downstairs?

No. The ceiling will be in the way.

Somewhat to my surprise, seemingly not always. A few months back, I saw what was under the upstairs floorboards of a modern house. It seems that the walls had been plasterboarded before the ceiling, since the wall pb extended up to a little above the ceiling - and, had it been dot & dab, I presume that I would have been able to see (and have access to) to the void behind the board.

Kind Regards, John

 

[EFLImpudence]

Somewhat to my surprise, seemingly not always. A few months back, I saw what was under the upstairs floorboards of a modern house. It seems that the walls had been plasterboarded before the ceiling, since the wall pb extended up to a little above the ceiling - and, had it been dot & dab, I presume that I would have been able to see (and have access to) to the void behind the board.

I suppose "there's always one".

Are the wall boards not supposed to support the ceiling (edge)?

 

[sparkwright]

I suppose "there's always one".

Are the wall boards not supposed to support the ceiling (edge)?

They are, that's how it's normally done, but there will be exceptions I suppose.

 

[JohnW2]

I suppose "there's always one". Are the wall boards not supposed to support the ceiling (edge)?

That's what I thought!

As you say, "there's always one" - although it seems that there are probably many. The house I saw was one of countless on a very large estate of recent new-builds, and I doubt that they singled out that one house to be dealt with differently from the others!

Mind you, it seems that, in the days before plasterboard, things may have been different. The interior walls in my house were originally all lath & plaster and, in many cases, that extends a little above the (also originally lath & plaster) ceilings - I suppose that when there was no board that had an edge which could be supported, it probably didn't make much/any difference which way around it was done?

Kind Regards, John