New to forum - advice needed on lathe ceiling

[paw61]

Hi everyone,

We've just embarked on the renovation of a very early Victorian (late Regency) terraced house and, as it's our first project and we're relative novices I'd really appreciate some advice on several things but in the first instance on the repair/replacement of our ceiling in what will be our kitchen.

The entire house was originally lathe and plaster which has in various placed been repaired using a variety of building methods. In the kitchen it looks as though the lathes have been kept but insulated behind and plaster-boarded over, possibly at the same time that the roof tiles (slate) were replaced by concrete tiles). I'm in slight disagreement with our builders on this issue as I'd like to keep the lathes where possible, renew the insulation underneath and then put new boards over. However, they are saying that this would be expensive, unnecessary and that we could risk the ceiling falling in at a later date. Their solution is to take all of the lathes down, board between the joists using an insulated board and then plasterboard over. I'm concerned that they are only saying this because it's the easy way out... Am I being too stubborn about keeping the historical fabric of the building or should I stand my ground?

We also have a similar issue with the plaster on the walls throughout the house which has come away in patches as we have removed the wall paper... at the moment we need to decide whether to replaster using lime plaster or take their advice and use contemporary building methods...

HELP!

Thanks in advance

 

[livias]

Hi and welcome to the forum

I assume from your mention of roof tiles that this kitchen is a single storey extension which is why you need insulation in the ceiling. If so ...

The ceiling is not likely to fall down when it is held in place by layers of insulation, plasterboard and fixings into joists so we can discount that as a spurious argument. I suspect that the reason your builders don't want to use lime is that they are not familiar with it. Lime plastering is not taught in college these days so many builders have never done it and are not aware that old houses cannot be treated in the same way as new houses. I am not sure that you have the right builders fof the job. If you are keen on keeping these builders then how about calling in a specialist lime plasterer as required? You should be aware that lime plastering costs more than gypsum, partly because it needs more tending than gypsum and partly because lime plasterers are in demand.

Your house was built to be breatheable so to avoid trapping damp you would be wise to use lime plaster on the exterior walls. Interior walls are optional. As to your kitchen ceiling, I can't pronounce either way at this distance but is your current insulation looking at all damp cos if so then I would go for woodfibre board and lime rather than plasterboard and gypsum. I think I would probably sacrifice the laths. You should have a layer of insulation board under the rafters too to stop cold bridging.

And finally, being picky. The word is lath not lathe. A lathe is used for turning wood or metal. A lath is a substrate for plastering on

 

[TheRoost]

Stand your ground, sack the builders.

Little confused why you want to keep the lath ceilings but cover them over with plasterboard? it would make more sense to remove existing boards then either repair laths/lime plaster where necessary.

Ignore their advice on the walls, if most of the walls are fine/solid you could patch repair with lime plaster. My house walls were previously covered over with plasterboard and gypsum, it has cracked and swelled up in the corners and where it meets window frames and architrave, I hate it and it will take me years to sort out.

 

[malcolm]

Modern builders will be reluctant to use traditional techniques because they haven't done them before and don't know how to. Their preference would understandably be to rip it all out and do it the way they know.

Some advantages of a lath and lime plaster ceiling (instead of plasterboard) are you can have a huge leak from above and the ceiling will sweat it off instead of falling down, and you don't get the horrid cracks appearing between boards when the building moves.

Trick will be finding the instructions for doing it the traditional way and giving them to the builder. For me so far I've just used NHL 2.5 (available from Buildbase) and treated it like cement, but spraying a bit of water on it every day for a couple of days for luck. Others might be able to point to more sensible or detailed guidance, and I've still not figured out what sand to use for finishing plaster.

New lath in the photo before plaster (DIY effort).

 

[plasticpigeon]

You need to use hair in the plaster over laths so it can flex a bit. I used premixed lime finishing plaster, but I believe that silver sand can be used at a 1:2 or even a 1:1 ratio. Sponge float is a Godsend. having said that, overboarding over the original ceiling is not the end of the world, it is an awful lot simpler than repairing or reinstating a lath ceiling. It depends on what kind of restoratioon you are doing.

 

[Keithj]

I would be reluctant to use gypsum plaster if the outer surface is lime. The folks who repaired my house used plasterboard and gypsum on the inside walls where they thought it "wouldn't matter". Turns out it did matter. The walls are now blooming and showing a variety of colours (mostly centred around brown). I'm debating whether to hack it out and have a go at lath and lime, or just sand it down yet again and dob on some more white.

 

[plasticpigeon]

Keith, is the blooming on stud walls or solid masonry walls??

 

[livias]

I can see why the op does not want to replaster the laths in their kitchen ceiling. They want to improve the insulation and that will have to be done from below

 

[Nigel Watts]

I can see why the op does not want to replaster the laths in their kitchen ceiling. They want to improve the insulation and that will have to be done from below

Living in an old building involves making compromises, particularly if one wants to treat it sensitively. I would keep the laths, use lime plaster and, if there is no access to the roof void, live with the insulation that is there.

Is the building listed? If so you should consult your CO before replacing the ceiling, even if it's a horrible modern one. There is little consistency between COs' views on such matters; some may want lime others may be happy with gypsum. Fifteen or so years ago when I started doing up my early Victorian Grade II listed semi I had little awareness of the benefits of lime plaster and was rather surprised when the CO insisted it be used with for a bedroom ceiling. He specified that it should be done over stainless steel mesh, not lath.

Most builders can't do lime plaster so there is no point asking them unless they know a good subcontractor who can. It is now a specialist skill and will be more expensive than gyprock with a gypsum skim. How much do you love your house?

I am currently restoring my lathe ;-)

 

[plasticpigeon]

What is the point in using lime for ceilings apart from keeping the construction as original? Using lime over stainless mesh isn't original construction so it seems an odd choice.

Nice Myford, I have a model "M".

 

[MatthewC]

What is the point in using lime for ceilings apart from keeping the construction as original? Using lime over stainless mesh isn't original construction so it seems an odd choice.

If your upstairs ceilings are lime plastered then the ceiling breathes just like the walls, so you are less likely to get damp mould in the corners etc as all that damp warm air rises. And the lime/mesh combination will flex rather than crack.

I also have Thermafleece in my loft - I think it was 270mm (2x100mm plus one x 70mm) but I'm not going up there to check!

 

[Keithj]

Keith, is the blooming on stud walls or solid masonry walls??

It's on the gable end wall - timber frame, lime on laths outside, wool in the middle, plasterboard and gypsum on the inside. If I'd known then what I know now...

 

[paw61]

Thanks for your replies everyone.

The consensus seems to be that where possible we use lime plaster... With this in mind, does anyone have any advice on 'how to'? And/or where to source relevant materials?

Thanks again, and in advance

PS thanks for the correction

 

[garnett]

Plastic Pigeon

Still a Hardinge fan as I worked for them as a lad.

I have recently specified mime plaster on EML as a compromise to achieve 1 hour fire protection in a listed building. I wanted to preserve the appearance and breathability. It had recently had a serious fire so going back as new but in a listed building. Some of us COs don't mind compromising occasionally!

Garnett

 

[plasticpigeon]

Ooh, hardinhe are a bit high end for a hobbyist like me, but beautiful pieces of machiiner, even if they are American.

Interesting about the ceiling. Is breathability really important in a ceiling? I understand that plasterboard won't survive in a damp environment, where as lime will, but if a ceiling isn't breathable what problem will it cause? Is it a conensation/surface moisture issue??

 

[Flyfisher]

Possibly a controversial point, but isn't EML (especially stainless steel) actually better than traditional lath in the sense that it performs better while having no downsides in terms of its affect on a building? Or perhaps there are ones that I can't immediately think of?

I wonder how many original lath and plaster walls have been lost forever because builders of old had to use iron nails that rusted away.

We all favour lime over cement for very good reasons of different performance, but where a modern material is available should we not consider using it if it is invisible and non-detrimental? How many of us would use non stainless steel fixings in green oak these days, for example?

 

[livias]

How to ... if you want to do it yourself then best go on a short course.
Where to source ... whereabouts in the country are you?