lath & plaster - why stainless steel?

[em]

HI many thanks for all your help so far - maybe oneday I'll learn enough to actually help someone else!

In the mean time...we are lathing between the beams in one of the bedrooms, we have secured timber battons to the edge of the beams and have attached the laths to the battons (so beams still visible).

We have just about finished and someone has said we needed to use stainless steel screws in the laths. But someone else has said only stainless steel if going into oak because of the tanning?

Does anyone know if galvanised nails will be ok on the laths as they are going into softwood battons or is there a reaction to the lime plaster?

Many Thanks!

 

[skier-hughes]

I was told by our plasterer and electrician to use stainless steel mesh to cover the wires as galvanised gets eaten by the lime.

 

[biffvernon]

I should think galvanised nails would be fine. Actually even non-galvanised would be ok in a dry place. It's indoors so any rusting from the wet lime won't get far. With oak there's an acid environment and you get a reaction between the tannins and steel so stainless or brass is adviseable. Lime is alkali and so is the metal so there's less problem.

 

[Penners]

I've used galvanised nails for exactly this purpose on a number of occasions.

To the best of my knowledge, none of my ceilings are now floors.

 

[em]

THAT IS GREAT NEWS!

Would be slightly upset if had to redo as its taken me 4mths to lath out the entire ceiling!

Yet again many thanks to all!

 

[Ian Bond]

When doing repairs I've found perfectly sound 200 year old iron nails in laths, and others that have rusted and broken. The water damage that had done for the nails had certainly done for the lath and plaster anyway.

The reason I use stainless steel screws with lath repairs, is that I'm also using stainless steel washers. I want the repair to be a durable as possible. I don't mind paying the extra for the stainless because I am using so little of it, and by repairing the ceiling myself saving a lot of money overall.

I use galvanized clout head nails for most lathwork as they are easily available. How much better they are than the original iron nails is anyones guess, and not worth worrying about!!!!

When repairing small areas of L&P walls, if I have to fix new lath I screw them in place using stainless steel screws. The vibrations from hammering could cause more damage, and you certainly get covered in more muck that way. Again, stainless only because I've found some very useful screws for this purpose, and I'm not using that many.

 

[michael]

My experience with galvanised edging is that it can rust with either lime or gypsum plaster. This I unfortunately discovered from plastering jobs done by the previous owners.
I’ve recently had some lime plastering done by specialist plasterers one of which has been plastering for more than 50 years. They insist on using stainless steel edging and stainless steel nails for fixing the laths but apparently when iron nails were originally used, they were dipped in linseed oil before hammering in. Apparently the linseed oil sets hard forming a protective coating around the nail. That being said, I’ve just removed a section of rain damaged lime ceiling plaster which had detached itself from the laths and whilst the laths were fine, the nails (presumably iron) were completely rusty but still firmly fixed.

 

[Ian Bond]

Linseed oil is not going to survive the abuse of being hammered into a rafter. Galvanized nails suffer similarly, and the coating will get damaged.

I think we are worring too much - the iron nails seem to do OK for a couple of centuries. Despite having to soak the wall/ceiling when you limewash periodically, and the odd minor leak.

 

[biffvernon]

Rusty nails grip more firmly

 

[Penners]

Linseed oil is not going to survive the abuse of being hammered into a rafter.

Well, I just tried hammering some linseed oil into a rafter. It splashed everywhere.

Did I do something wrong? :wink:

 

[piper]

I wonder if you need listed building consent to replace rusty nails with modern clean shiny steel ones? Shiny new nails are the start of the slippery slope that leads to plastic windows and perfectly flat gypsum plasterboard. (only joking )

 

[Penners]

Shiny new nails on a slippery slope?!

The very thought makes me wince.

 

[Ian Bond]

Nice one!
:lol:

 

[michael]

The trouble with galvanised is that if it scratches, which is often the case with both nails and corner edging, then rust sets in. Stainless steel on the other hand doesn’t rust.

As I understand it, dipping iron nails in linseed oil was the traditional way of doing things. Who am I to argue? The 200 year old nails that Ian mentions were probably also dipped in oil.

I guess that the linseed oil, to some extent, stays coated on the nail or otherwise soaks into the surrounding wood and then hardens to offer some degree of protection and slow down the rusting process. Better protection than scratched galvanised I would have thought but probably not as good as stainless steel.

My experience with rusting galvanised corner edging would keep me away from using anything galvanised in the building context.

 

[Ian Bond]

It's a good theory, but I can't see all plasterers going to that amount of trouble with the nails.

Just bang 'em in.

If you've ever lathed a ceiling, you'll appreciate the hard work the old boys did.

 

[biffvernon]

I did one this summer with oak laths. I used brass panel pins. Then lime plaster.

 

[Ian Bond]

You can't beat riven oak laths!

And brass pins - it is almost a shame to cover work of that quality with lime plaster.

 

[joatex]

The 200 year old nails that Ian mentions were probably also dipped in oil.

Most likely were wrought iron in contrast to mild steel

 

[K8]

The trouble with galvanised is that if it scratches, which is often the case with both nails and corner edging, then rust sets in. Stainless steel on the other hand doesn’t rust.

it does, it can corode (which is rust I thought) and salt is a catylst, hence marine grade stainless steel, though in most situations it is very stable I suspect I looked into it briefly as was looking for window fitments to combat rust in a very salty environment

 

[Penners]

It's important not to think of galvanising in the same way as painting.

The coating on the steel is not just a layer of zinc. The hot dip galvanising process produces four identifiable layers (known as Eta, Zeta, Delta and Gamma) which contain variously graded alloys of zinc and iron. These are attached to the steel substrate by a force of several thousand lb/in^2 (paint only "hangs on" by a few hundred psi at best).

Even if the galvanising is damaged, the steel substrate continues to be protected from corrosion by cathodic action.

So have a bit more confidence in your galvanised nails!