Chicken wire!

[worms]

I know I will get shot down in flames for this, but here goes!

Has anyone practical experience of problems caused by using chicken wire as a support structure for lime mortar instead of lath?

I know all the theoretical arguments against it - rusting, differential expansion rates etc. But is this purist or real? Does the expansion issue really hold true on an internal, insulated wall?

Chicken wire would be much cheaper (given the cost of getting materials delivered here) and would seem to me to reflect the local agricultural history of my converted steading more than lath, since the building probably never had any internal render before the gyproc was put up in the 40's.

OK, fire away!

 

[middi]

Chicken wire was frequently used on old buildings, usually nailed on existing weatherboards on exteriors of buildings to hold cement based renders and this aprroach condemned to death the exterior cladding as soon it cracked and water penetrated.We are still paying the price now for this ill informed approach of 50/60 years ago.

There has been some progress on this, if a number of non-conservation architect which specify stainless steel mesh for internal cement based rendering of barns is anything to go by

If you want to apply LIME render internally on flexible chicken wire you will have the best fun of your life trying to initially getting it to stay in situ and then more fun trying to apply subsequent coats on what should be reasonably flexible lime render. Chicken wire has not the surface aerea, the rigidity or the binding qualities to cope with lime plaster.

Cement based renders have different properties and will stiffen within a day or two, once solid the cement holds the wire in situ as opposed to genuine lime plaster were it needs the larger background surface aerea to hold itself up.

I am not advocating the use of cement at all, and if I wanted genuine lime plaster applied to the walls or ceilings, I would use a genuine tried and tested method to keep it where it is supposed to stay.

Apart from laths there are other useable substitutes you coul use, the reed type matting sold at garden centres for shading may be good.

 

[Gervase]

I can only speak on the basis of having to remove the stuff. It always rusts, and in rusting it expands, cracking the enveloping plaster. Which makes it easier to remove the plaster, leaving irritating strands of rusty wire nailed to the wall!
Even galvanised EML is prone to rusting - you only have to scratch the zinc coating with a hammer head, nail or plastering trowel to expose soft steel and then the rust can begin.
That said, rusting seems to occur less vigorously under lime plaster than OPC.
Instead of expensive riven lath, have you thought of the reed lathing now available? It makes an excellent substrate for plaster, doesn't rust and enhances the breathability of the wall. It's not much more expensive than chicken wire and a lot cheaper than EML.

 

[worms]

Thanks for the comments - knew I'd be shot down for the suggestion!

At the moment I only need to cover a relatively small wall (about 2.5m high by 1.5m wide and with a 1m by 1m window opening in it). Ordering small quantities of anything is always a problem in that delivery costs get silly. I'm pretty sure that with the small surface area between supporting battens and a flattened double layer of wire, it would be firm enough to plaster onto and give good enough contact to stick.

However, I will look into the reed matting.

I guess an alternative for such a small amount of lath is to find some wood and split my own laths, what wood is best? I think I have missed the chance of some chestnut logs locally (since chestnut reputedly burns badly, no-one wanted it, but I think it is all gone now). Plenty of dead elms around, though - would it split?

 

[middi]

Elm is difficult to split, oak is easier but hazel and willow is much better.

You could try the woodyards if there is any near you, they usually scrap timber fillets after they have sized timber for their customers, they give them away for a drink, just treat them and split them agaiin if they are too wide .

 

[worms]

willow is much better

Thanks, I've got a an old straight willow log in the garden I could try to split!

 

[Gervase]

Chestnut splits very well, and is extremely resistant to damp and the like. If you can find some old chestnut paling fence (the stuff held together with wire top and bottom), that would be ideal riven for laths.

 

[biffvernon]

Easy way is to get the 'screening' they sell at garden centres. There's a choice of willow, reed, and other sorts of sticks. Tends to be around a fiver a square metre.

 

[NT]

Since you've only got a small area I'd go with doing it the old way. But why split wood 100 times when you can just use a bunch of sticks.

NT