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Metal or dry lining back box

Updated: October 2026

You are holding two different boxes and the wall is either brick or a hollow stud, and only one of them will stay put. A metal or dry lining back box is not a style choice. The galvanised flush box is chased into masonry. The dry lining box clips into plasterboard with lugs. Use one in the other’s wall and the plate rocks, the screws miss, or you cut a hole you cannot fix with the box you bought. Depth bands stay on [25 mm or 35 mm](/hub/electrical-equipment/wall-box/sub/wall-box-depth). Prices in pounds stay on the [Wall box comparison](/hub/electrical-equipment/wall-box). If you have not yet ordered, the wider order of decisions is on the [buying guide](/hub/electrical-equipment/wall-box/sub/wall-box-buying-guide).

You are holding two different boxes and the wall is either brick or a hollow stud, and only one of them will stay put. A metal or dry lining back box is not a style choice.

Our top picks

Evoges Evoges EDB1G35 dry lining box

Best overall

Evoges Evoges EDB1G35 dry lining box
9.6/10about £8.99
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Lyvia Lyvia 25 mm metal wall box

Best value

Lyvia Lyvia 25 mm metal wall box
9.4/10about £3.68
View offer
LEENUE LEENUE 32 mm surface wall box

Rank 3

LEENUE LEENUE 32 mm surface wall box
9.4/10about £6.99
View offer
On this page
  1. 1.Use a galvanised flush box in masonry
  2. 2.Use a dry lining box in hollow plasterboard
  3. 3.Earth and fire are not optional extras
  4. 4.If you cannot cut, stop and use a surface box

Use a galvanised flush box in masonry

Brick and block give you something solid to chase and to screw into. The box for that wall is a galvanised flush pattress, set so the front finishes flush with the plaster and a 1-gang plate can pull up square. In this set that is the Lyvia listing: a 1-gang metal box whose bullets say 25 mm, knockout entries, and an earth fixing connection, for 1-gang faceplates. The technical details also print 7 × 7 × 7 cm, which conflicts with 25 mm, so the chase should follow the box you measure, not the cube on the page. Metal does not mean the listing has shown BS 4662. That standard covers flush-box dimensions and M3.5 lugs, and the Lyvia page does not print the number. A flush metal box will not grip plasterboard.

Use a dry lining box in hollow plasterboard

A hollow stud wall is the dry lining case. There is nothing solid to screw a metal box to, so the usual answer is a clip-in plasterboard box. The lugs pass through the hole and then bear on the back of the board. In this set that is the Evoges EDB1G35, a 35 mm box whose bullets say plasterboard or a hollow wall, spring lugs, and a flame-retardant material, with UKCA stated on the listing. Appleby’s sheets for this kind of box cite roughly 6.35–15 mm of board. The Evoges page does not publish a board thickness. A dry lining box does not belong in a brick chase. The lugs need a skin of board with space behind them.
Evoges Evoges EDB1G35 dry lining box

Testsieger

Evoges Evoges EDB1G35 dry lining box
9.6/10about £8.99
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Earth and fire are not optional extras

A metal flush box is conductive, so the circuit protective conductor has to connect to it through a sound terminal. The Lyvia bullets state that connection. The Evoges listing does not state an earth terminal at all. Approved Document B expects tested fire-stopping where a fire-separating wall is cut. A standard lug box is the wrong product there. A Scolmore FlameGuard metal dry lining box sold by TLC, listed around £3.96 including VAT, is an example of a named product with an earth terminal and cited fire tests. It is not the Evoges ASIN. The fitting sequence and that stop are on how to fit a back box.

If you cannot cut, stop and use a surface box

Sometimes the right answer is to cut nothing. Concrete, a lease that forbids chasing, a tiled wall, or a cable you can only bring in on the surface all point to a surface pattress. In this set that exit is the LEENUE box: a white 32 mm ABS shell, 86 mm square, sold for network and brush plates, screwed to the face of the wall. It does not become a flush box if you sink it into a hole. The pack is the box and two screws, without a faceplate and without listed wall plugs. The specification does not state an earth terminal or a British Standard. Use it when the plate, including a Cat6 faceplate, can live on the surface and 32 mm is enough for the cable bend. Outdoor use is not claimed. Masonry you can chase takes a galvanised flush box.

Common questions

Can I put a metal flush box in plasterboard?
Not as a normal fixing. A galvanised flush box is made to be chased and screwed into masonry. A hollow stud has a cavity behind the board, so those screws do not land in brick. Use a dry lining box with lugs that clamp the plasterboard, or a surface pattress if you should not cut. The Lyvia box is the metal flush example in this set, and it is the wrong example for a stud wall.
Can I put a dry lining box in brick?
No. The lugs need a sheet of board and a void behind it. In a brick chase they have nothing to spring against, and the box will not sit like a metal pattress bedded in the wall. Chase a galvanised flush box into masonry instead, at a depth the plate accepts. The Evoges box is specified for plasterboard or a hollow wall, not for blockwork.
Does the metal box need an earth the plastic one does not?
Yes. A metal box has to be connected to the circuit protective conductor through its earth terminal. The Lyvia bullets state an earth fixing connection, and one review says that lug sheared. The Evoges listing does not state a terminal. On a plastic box the earth usually ends on the accessory. Sleeve bare earths in either case.
Is a fire-rated metal dry lining box the same as a normal one?
No. A fire-rated metal dry lining box is a tested product for a fire-separating wall, often with its own earth terminal and a stated performance. A standard plastic lug box, including the Evoges listing, does not carry that claim. The TLC Scolmore example is a different catalogue line. Do not transfer its tests, or its price, to the amazon.co.uk dry lining box.
What if I must not cut the wall at all?
Use a surface pattress and accept that the plate will stand off the wall by the depth of the box. In this set that is the LEENUE 32 mm ABS box, screwed on with plugs you supply. It suits a data plate when a chase is refused. It does not suit a flush socket, an outdoor position, or a fire-compartment penetration you were hoping to avoid with a smaller hole.

Related pages

Wall box

Best back box for plasterboard, brick, or a surface

What size back box do I need for a UK socket plate?

25mm or 35mm back box: match the plate, not a slogan

How to fit a back box once the circuit is proved dead

Sources

Public UK sources are listed below. Shelf prices and star lines are the amazon.co.uk figures checked on 21 October 2026.

  1. BS 4662: boxes for flush mounting of electrical accessories (retrieved 21 October 2026)
  2. BEAMA Technical Bulletin: selection of boxes (retrieved 21 October 2026)
  3. Approved Document P, electrical safety (retrieved 21 October 2026)
  4. IET: Part P frequently asked questions (retrieved 21 October 2026)
  5. IET: Part P in Scotland and Northern Ireland (retrieved 21 October 2026)
  6. Electrical Equipment (Safety) Regulations 2016 (retrieved 21 October 2026)
  7. Socket Store: what is a back box (retrieved 21 October 2026)
  8. NHBC: earth bonding of metal back boxes (retrieved 21 October 2026)