Lime / Hair Plaster

[Onoff]

I've an 1865 mid terrace cottage. The plaster on the walls is what I believe is lime plaster with horse hair mixed in. It's thick and fibrous. Try and put a Rawlplug in and you're on a loser. I used to drill a hole and push the Rawlplug in with gripfill etc.

I'm thinking to redo the walls of 4 rooms in what is basically a two up / two down.

Skimming over isn't really a goer. It rings hollow in multiple places. Just mulling options really. Once I strip it back to brick then I can:

1) Render & plaster

2) Dot and dab plasterboard onto the walls then tape and joint.

Years back I repaired some blown areas by applying browning or maybe bonding I think it was called. I was only a kid a tbh made a hash of it. Built it up in real thick layers.

Likely doing this in conjunction with removing two downstairs ceilings that are lath and plastered. One too has polystyrene tiles on. That and a full rewire and central heating replacement. I'm even debating removing the two downstairs suspended floors and building back up with an insulated slab with UFH.

Also considering a positive input ventilation system.

To help in my decsion making is "modern" sand and cement render OK followed by a multifinish plaster?

I know that "sealing up" old houses that were meant to breathe can be a bad thing but if I mitigate against that...

Cheers

 

[julianf]

Is there any issue with damp?

I'm assuming that the walls have been finished with modern paints anyway, so will have largely made the lime non-breathable but do check properly for any damp, as, if present, replacing the lime (even if it's been partially negated by modern paint) will make the situation worse.

If it really is dry, and you want to use cheap / modern materials, it's hardwall and multi.

Edit -

Or glue on board and multi.

 

[julianf]

To follow up -

If you're paying someone else to do the plastering, you'll, of course, save yourself some money by boarding it rather than hardwall.

Hardwall will add to a skilled plasteres work / bill, but, if you make a nice job of boarding it, then all you'll need to pay for is someone to come in and slap a couple of quick coats of multi or board finish over the whole lot.

 

[brightspark]

if i was doing dot and dab boarding which will be quick and the best id make sure the walls would be dry and not damp if it were id knock all the plaster off drill and inject cream and tank it 1st

 

[Kayos]

Don't render it with cement unless you want massive problems in the future

Either knock it all off and start again or knock the blown bits off and patch it

 

[Onoff]

if i was doing dot and dab boarding which will be quick and the best id make sure the walls would be dry and not damp if it were id knock all the plaster off drill and inject cream and tank it 1st

I injected a liquid dpc years ago. I reckon it made issues worse. Pretty sure where I injected is where it's blown the worse. Will have to check and see if I can spot the injection holes.

 

[brightspark]

I injected a liquid dpc years ago. I reckon it made issues worse. Pretty sure where I injected is where it's blown the worse. Will have to check and see if I can spot the injection holes.

may be salt damage then on the surface then should have treated with antisulphate salt neutralizer

 

[julianf]

I injected a liquid dpc years ago. I reckon it made issues worse. Pretty sure where I injected is where it's blown the worse. Will have to check and see if I can spot the injection holes.

I take it from that that you have had damp issues.

I also know that those injected systems are rarely entirely successful. This is likely confirmed by your comment about making the issues worse.

Given the above I would suggest you replace with a breathable plaster on the ground floor walls.

 

[Onoff]

Given the above I would suggest you replace with a breathable plaster on the ground floor walls.

I wonder if I could dot and dab moisture resistant plasterboard onto the walls?

I'll take some pictures sometime.

 

[julianf]

I wonder if I could dot and dab moisture resistant plasterboard onto the walls?

I'll take some pictures sometime.

You would get damp lines between the boards, or worse.

There are loads of ways that people try and battle damp. The one I've seen that works more reliably than others is permeable finishes, rather than attempting impermeable (which never seems to work well when applied afterwards)

 

[julianf]

Mike wye (and probably others) sell a wood wool system. I can't say I entirely see the point of it (against other options) but I've been asked to use it before and the set works well.

You get boards that are like dried noodle blocks (made of wood) that you affix like plasterboard. You then skim it with a couple of coats of a nhl concoction that has cork in it also. It's kind of similar to bonding, in that you can fill voids a bit with it, but it's permeable, unlike bonding.

Then you skim over that with another nhl mix (they sell it all, it's just dry bagged stuff) and then, if you want, a final coat of lime putty.

So it's 4 coats, over 2 days or 5 coats over 3, but it does the job.

You can use it on walls or ceilings, but expect ibuprofen breakfasts when you're doing a lot of ceiling work with it...

 

[julianf]

Here you go -

So, yeah, board and then 5 coats. I'd have just used plaster board and gypsum as permeability wasn't important in the application, but it's what the client wanted.

You can use it on walls also.

 

[Wozzaaah]

We recently had our hallway and stairwell done in “lime lite”.
It’s a breathable “plaster” which I believe consists mostly of perlite. Not cheap but far cheaper than proper lime plaster and less nasty to work with. The chap who did it swears by it, he uses it a lot in cellars.

 

[Onoff]

A weird aside, I recall, vaguely, that half way up the ground floor brick walls is what I can only describe as a 4x2 wall plate. The bricks then carry on above this.

Back in the day I'd buy the black cans of waterproof Unibond PVA and use it at 5:1 in everything. Cement, plaster, concrete etc. The areas I did in that are rock solid still and I don't think have any damp.

 

[Gritineye]

A weird aside, I recall, vaguely, that half way up the ground floor brick walls is what I can only describe as a 4x2 wall plate. The bricks then carry on above this.

Most likely to fix paneling to, wood paneling hid a lot of damp issues before DPC became common.

 

[Gareth J]

Have been using some bags of insulating lime render recently for extrlernal walls on a solid wall house. May be similar to wozaahs limelite. A bit fussy to apply (shrinkage) but ok and pretty forgiving. A tiny bit insulating but a huge moisture buffer. I got bags cheap, that were almost out of date but you'd think there must be cocaine in the mix the price they normally charge. Looks good on a knobbly walled cottage but a board product might be easier if after straight/flat walls.

As an aside, I have, tentatively, been using cheap hydrated lime as an alternative for fancy lime products which I've always been suspicious may be sold with a copious helping of woo. Structurally have no issues yet (long drying times), fine for whitewashes, mixed with pigment makes a very affordable "paint". But no good as a finishing plaster - there are too many bit of sandy stuff in it and, after a couple of years, there have been a few pinhead sized blows for some reason or another.

 

[brightspark]

id be watching yourself stripping the plaster off lime and horsehair might contain anthrax get that in a cut and you will know about it wasn't just horsehair they used

 

[addjunkie]

The more you talk about this job….the more Im thinking move itll be easier…… or at least budget to move out while you do it, neigh in impossible to do ufh and replaster house, rewire, new heating while your Mrs is living in it! This is our bedroom, so Ive got this T shirt!

 

[winchman]

Have a look at Peter Wards Book on Damp in old buildings. The Lime allows the building to breath, modern stuff wont allow this and you may well end up with Damp issues.

Heritage Survey | The Warm Dry Home

The Warm Dry Home:Whether you live in a Victorian brick terraced house, or a 7 bedroom Cotswold stone country mansion, this book is for you.Home owners, Building Surveyors, Architects, Engineers, Builders and Environmental Health Officers will learn from a wealth of easily understood...

www.heritage-survey.org

 

[Stueeee]

Do the walls actually feel damp/wet when you touch them? If not I would have thought plasterboarding dot an dab would work OK. This photo was taken when I was doing my 'Mad Max' impersonation at a Friends 18th century watermill in SW France. Actually I've just cut a doorway through the stone wall -hence the French Acrow type things supporting the wooden needle. Point being that my friends dot and dabbed the walls (the one behind me is 2M from the mill race) with plasterboard straight afterwards and they still look good now.