Light switch on a hollow slatted stud wall

[greenforehead]

Hi all,

I've been updating our Victorian terraced home and have just replaced all of the electrical sockets in the living room with those flush, brushed chrome jobbies. I bought a matching dimmer for the light but then hit a problem...

The existing wall box is too shallow for the new switch so I bought a new 35mm box to replace it. This morning I removed the old box to discover the reason why such a shallow box was used; it's on a stud wall that consists of plaster over wooden slats wih a cavity behind. To fit the new box flush I would need to saw through the slats but there will be nothing behind to secure it to (it doesn't appear to be anywhere near a stud).

To secure it to the slats on the opposite side of the wall I'd need screws about 6"long so the only thing I could think of is passing a small piece of timber through the hole and screwing it to the slats on the opposite side and then securing the box to that.

Being a complete novice at such things I thought i'd come here first and ask the experts whether that seems a sensible idea or whether there are any better options. Can you help?

Cheers

Al

 

[TonyW2]

Bit of ingenuity.
Piece of plywood inside the "hollow" part of wall.
Two pieces of ply secured to it to act as "washers" thickness suitable to hold it away from the interior surface of the laths. (at distance suitable for depth of box)
Thin ply pieces (as washers) outside the laths (bury in plaster)
Screw from outside, through ply, laths,washers and into backboard ply.(May need a bit of wire to hold the interior ply piece, whilst fixing.

Or--probably more work--locate studs and attach a noggin or batten between them within the cavity of the wall. Make good the openings needed to facilitate the fitting of that batten.

 

[securespark]

Bit of 2 x 1 passed into the hole and fixed by screwing through lath into 2 x 1 using 2 or 3 screws on either side. The holes can be filled afterwards.

Or, with care, you could fit a dry line box, depending on the friability of the lath & plaster.

 

[greenforehead]

Chaps,

Thanks for the advice.

I was going to have a stab at this next weekend, screwing a piece of timber through the wall as suggested.

However, the wall is approximately only 12 inches wide, adjacent to the living room door frame and an internal supporting wall. Tapping the wall suggests the cavity only extends approx 3 to 4 inches either side of the light switch.

With this in mind, rather than trying to work through the recess in which the wall box will sit (which is what, not much more than a couple of inches square) do you think it would be better to take out an entire section of the plaster between the top and bottom of the light switch?

I was thinking that doing this would be less fiddly and I could cut the laths and then run a longer length of timber behind them, secured to the studs and the sawn halves of the 3 laths I'd need to cut. I could then fix the box and easyfill both sides.

Does this sound sensible or am I lining myself up for a disaster with parts of the wall falling away do you think?

Cheers

al

 

[ban-all-sheds]

Depending on your attitude to historical accuracy, design integrity, building narrative etc, you might find it quicker to remove the whole 12" wide section and put a piece of plasterboard up.

 

[greenforehead]

Yeah I did think about that but we have the original cornicing and I didn't want to mess with the wall that high up for fear of damaging/losing it.