Newtonite Lath - Damp Treatment

[terlg]

Hello everyone

I've just bought a lower ground floor flat in a 4 storey Victorian terrace - c.1880s.

When we had our survey done the surveyor found only a small amount of damp issues on the kitchen wall in the rear extension of the property (very old but not original-extension).

On closer inspection and removal of cabinets the plaster work fell away to reveal what I think is some Newtonite Lath from a few decades ago. It's essentially corrugated carboardy material, painted in bitumen by the looks of it and sits just away from the party-wall. just like this: http://www.plasterersforum.com/threads/what-is-this-stuff.36995/

Having now looked down the rest of the wall it would appear to have this layer from front to back along the party wall.

It's not in great condition and there are a number of holes in it where previous residents have hung radiators/paintings and fixed shelving to it.

I'm about to rewire and want to sockets on this wall so will definitely disturb/make more holes in it.

Should I be replacing this newtonite layer with some other damp treatment? The wall itself seems to have little issues (probably because the layer is working) so I don't want to be the catalyst for causing more problems. That being said the kitchen has significantly improved since removing the cabinets and someone living in the flat (sat empty for a couple of years) and I suspect the main issue is down to the floor having been filled in some 7-10 years ago with concrete.

Any thoughts would be welcome.

 

[Abi Cott]

I would be looking to replace it with something that handles the damp in a similar way. If you plan the sockets in from the start rather than adding them after, you can have them without compromising the damp protection.

 

[DavidB]

Have you spoken to the neighbour of the party wall - what's it like on their side? The damp doesn't just disappear because the wall is lined - it has to go somewhere - and it doesn't just go back down into the ground . It might go up the wall and into the ceiling joists for example.

How about this idea... strip everything off the wall. Baton-out the wall, apply plasterboard to the batons. Cut vent holes above the cabinets and low down the wall. Then install vents in the holes. That way there will be air circulation behind the plasterboard and the damp will evaporate. Depending on the size of the wall I might do 4 vents - 2 high and 2 low. The only issue with this idea is:
1. you lose the batons depth from your overall room width - if you strip off all the plaster back to the brick then that will offset some of that loss.
2. Unless the batons are installed against a damp proof backing they will eventually rot - I'd treat them with wood preserver and then I'd line the backs with a thin damp proof liner using staples to attach the liner to the thin batons.

Are you saying the cement floor pre-dated the newtonite or the other way round i.e. that the newtonite is older than the cement floor? If the latter - what else could be causing or adding to the damp - do you have raised ground levels outside, are the air bricks blocked up, are there any broken or poorly installed rainwater pipes anywhere around that area, or overflow pipes showing signs of discharging, plants growing up against walls, external cement render? Of course the problem might be the cement floor was installed a long time ago and that caused the issue that someone tried to hide with the newtonite and then at a later date someone just laid a new screed on top of the old cement hence why you think it is only 7-10 years old and the newtonite is a couple of decades old.

I would try and identify every source / cause of the damp and try to improve or eliminate them one by one - you might find it difficult to fix them all - but you might improve it enough by picking on the easy to fix items. I would speak to the neighbour behind the party wall - as they might be experiencing even worse issues or they might be contributing to the problem i.e. if they have cement render on their side or a leaking pipe or something.

Good luck and remember there is always some kind of solution - its just a balance of what is affordable, practical versus the benefits.