Plastic back boxes for lime plaster

[tvrulesme]

Replacing some back boxes in a room which is due to be plastered with Lime plaster.

Galvanised steel is known to slowly react to lime and in fact the boxes I am replacing have rusted badly so considering using plastic dry lining boxes instead of galvanised.

Is there anything in the regulations which would advise against this? It's for a kitchen if that makes any difference?

 

[littlespark]

Yea, you can get them. Just the same as metal boxes, but in plastic.

Nothing against them in regs. No difference than any plastic surface box

 

[LukeD]

As above all good to go ahead with plastic

 

[123]

Don't use dry lining boxes though, that would be a bit shoddy. Use plastic flush boxes...Marshall Tufflex make them

 

[nicebutdim]

2 Gang 35mm PVC Flush Box Round Corners with 20mm Conduit KO White (Sold in 1's)

4 x 20mm entries on horizontal sides, 2 x 20mm entries on vertical sides

www.cef.co.uk

 

[LastManOnline]

As above all good to go ahead with plastic

The only slight downside with plastic boxes is price. Otherwise its all uphill.

 

[suffolkspark]

I work out in a lot of rural properties here lime plaster is common, I've never found a corroded box in lime unless the wall is damp

 

[tvrulesme]

The only slight downside with plastic boxes is price. Otherwise its all uphill.

Tell me about it. It's a listed building so pretty much everything I touch is super pricey.

 

[tvrulesme]

I work out in a lot of rural properties here lime plaster is common, I've never found a corroded box in lime unless the wall is damp

There was a lot of damp but I'd rather be safe than chance it.

From my searches:

"Lime attacks steel and galvanisation is only a thin coat of zinc over the top of mild steel, so any slight removal of this protective covering will allow the moisture in the render to rust the steel. The galvanised steel will also slowly react with lime and this will cause the structure to fail as the rust expands and cracks the render."

 

[tvrulesme]

Don't use dry lining boxes though, that would be a bit shoddy. Use plastic flush boxes...Marshall Tufflex make them

Agreed and all the plaster would push in to the slots. Thinking of these as their not ridiculous in price

PVC Surface Box

 

[LastManOnline]

2 Gang 35mm PVC Flush Box Round Corners with 20mm Conduit KO White (Sold in 1's)

4 x 20mm entries on horizontal sides, 2 x 20mm entries on vertical sides

www.cef.co.uk

Great box. But horrendous price.Can appreciate the reluctance to use plastic

 

[telectrix]

just use plastic surface boxes sunk in.. virtually the same but a fraction of the cost.

 

[nicebutdim]

Great box. But horrendous price.Can appreciate the reluctance to use plastic

Probably available for much less, but CEF provide a decent online resource

 

[123]

just use plastic surface boxes sunk in.. virtually the same but a fraction of the cost.

Good luck with that, they are anything but the same as there is no forgiveness if you set a surface box into the wall. The faceplate has no overlap so the box has to be set perfect, and the plasterer has to work to that the same way they would with a door frame.

 

[LastManOnline]

Good luck with that, they are anything but the same as there is no forgiveness if you set a surface box into the wall. The faceplate has no overlap so the box has to be set perfect, and the plasterer has to work to that the same way they would with a door frame.

I, m inclined to agree with that assessment. Could see a lot of headaches arising from it.

 

[7029 dave]

Just a thought could you not red oxide the metal boxes before you install them.

 

[Pretty Mouth]

Just a thought could you not red oxide the metal boxes before you install them.

Galv steel is an awkward surface to paint, not much takes readily to it. IIRC you have to use something called mordant solution before priming

 

[pc1966]

Great box. But horrendous price.Can appreciate the reluctance to use plastic

As @nicebutdim says, you will probably get them from another wholesale outlet for quite bit less then CEF.

 

[LastManOnline]

As @nicebutdim says, you will probably get them from another wholesale outlet for quite bit less then CEF.

Here is the interesting bit. Just out of curiosity I rang CEF this morning (ROI). He quoted me 1.50 euro for a double box. I then looked up a number of wholesalers in N. I., assuming they would be readily available, but no.Looked up Screwfix. They don, t stock them. I always assumed pvc flush boxes were a UK product exported to ROI. But no.They appear to be an ROI product that's little used elsewhere

 

[nicebutdim]

I wish I'd known about these a few years back but, since first being made aware of their existence, they're firmly imprinted in my mind. Not sure I see price being much of a problem, unless you were planning to use them on every job, but for an occasional damp wall a couple of extra £ is of no consequence.