Double layer plasterboard backbox

[PCAnimal]

Will a double layer of plasterboard take a plasterboard backbox? Being double thickness i would think it could struggle to grip.

Any views?

 

[John D v2.0]

Should do, but you can always cut the back layer bigger than the front if you have access behind or before hand.
The screws should tighten onto any thickness.
The other option is to cut the front layer wider and recess the back box.

 

[plugwash]

In my experiance plasterboard backboxes work by having "wings" that are pushed out the side of the box. The plate screws then draw these wings forward clamping the plasterboard.

So the question is are the wings on the box far enough back to push out behind the plasterboard. If they are then you are fine, if they are not then I don't think you will be able to install the box at all. I don't think a scenario where you can fit the accessory but the box doesn't grip the wall is a likely outcome.

http://www.farnell.com/datasheets/1959096.pdf claims that for appleby dry lining boxes the acceptable thickness range is 6.35 to 15mm. It seems plasterboard is 9.5 or 12.5mm thick so two sheets would be 19mm or 25mm which is out of spec.

http://www.mkelectric.com/Documents/English/EN MK Catalogue/Boxes.pdf claims 6-16mm for their standard dryline boxes, slightly wider than the appleby but still not enough It doesn't say for their intrumesent ones.

I expect with some digging and scraping using a knife you can remove a section of the rear sheet of plasterboard through the box hole.

 

[rsgaz]

http://www.builderdepot.co.uk/1-gang-dry-lining-box-47mm.html

Up to 30mm plasterboard thickness.

 

[PCAnimal]

Thank you all. I will attempt the cut to start with and hopefully it will be enough

 

[Jackrae]

You might get the box in and secured but only rear entry for the cables unless you do lots of 'digging'

 

[nickjb]

Mine didn't, and I used 47mm boxes. I had to cut the rear plasterboard away, which is actually quite tricky when working from the front through the hole.

 

[JohnW2]

Mine didn't, and I used 47mm boxes. I had to cut the rear plasterboard away, which is actually quite tricky when working from the front through the hole.

In my xperience, it can certainly be pretty difficut with a 'single' box. However, with a double' box, there is usually enough space to get the likes of a Stanley knife in and gradually 'pare away' at the back layer of plasterboard.

Another approach, if one is very careful and doesn't mind the clouds of plaster dust, is to use a router with the (largeish, straight) bit adjusted so that it 'gets' just the back sheet. That approach works with single, as well as double, boxes.

Kind Regards, John