Lime plaster application thickness

[james9570]

Hi all,

I'm looking to re-plaster the inside of an exterior facing Victorian wall in order to match the other gypsum plastered walls in the room. I have contacted Mike Wye for technical advice and they recommended the following:

3 mm scat coat of Reabilita Cal CS
15 mm scratch coat Haired Lime Mortar
10 mm float coat Unhaired Lime Mortar
2 mm coat of Heritage Lime Plaster
1 mm top coat of Regency Plaster

I have the following questions:

1. Is this not quite a thick application in total, at just over 3cm? Could we get away with a thinner application overall? Mike Wye technical support said above is all they could recommend.
2. Would I require an expert in lime plastering to do this sort of work? My builder is familiar with standard gypsum plastering, would this sort of work be similar?

Thank you all in advance for your advice!

 

[a twig]

That seems bonkers frankly. I’ve never heard of doing more than 3 coats…

Also odd to mix an NHL and a fat lime in the same system…

With the aid of a couple of YouTube videos to explain what I want I’ve found a lot of plasterers happy to do lime even with limited previous experience but your mileage may vary

 

[Lacan07]

Hi all,

I'm looking to re-plaster the inside of an exterior facing Victorian wall in order to match the other gypsum plastered walls in the room. I have contacted Mike Wye for technical advice and they recommended the following:

3 mm scat coat of Reabilita Cal CS
15 mm scratch coat Haired Lime Mortar
10 mm float coat Unhaired Lime Mortar
2 mm coat of Heritage Lime Plaster
1 mm top coat of Regency Plaster

I have the following questions:

1. Is this not quite a thick application in total, at just over 3cm? Could we get away with a thinner application overall? Mike Wye technical support said above is all they could recommend.
2. Would I require an expert in lime plastering to do this sort of work? My builder is familiar with standard gypsum plastering, would this sort of work be similar?

Thank you all in advance for your advice!

I agree with Twig, thats seems a bit over the top. Why is a scat coat required, is it a 'problem' wall?

Either choose NHL or non hydraulic, theres no need to mix the two up. For maximum breathability use non hydraulic and the standard procedure is a 3 coat system - scratch (base), float, and skim. I also don't understand this obsession with this 'final' final (Regency) skim. Its unnecessary, you can get a perfectly decent polished finish with a standard skim.

 

[james9570]

Not at all, it’s just a pretty standard brick wall. Some pretty minor damp issues when it was previously finished with gypsum plaster.

What thickness for each coat would you recommend, just so I know how much to buy?

 

[james9570]

And could you recommend any YouTube videos I could watch to show my builder?

 

[skierhughes]

And could you recommend any YouTube videos I could watch to show my builder?

Ty-Mawr do a series of 20 covering each stage or lime plastering.

Lime Plaster Application Guide

Lime plaster application guide. A how to, step by step on how to use Ty-Mawr's Internal Lime Plaster. using conventional plaster.It is highly recommended to ...

www.youtube.com

I use two coats of 9mm and one or two coats of 2mm. (depends on the quality of my bottom coats and my walls are very higgledy piggledy!!

Go to their website and input your wall dimensions and they'll tell you how much of each coat you'll need. (I expect other lime suppliers offer the same service.)

I buy their 25kg ready mixed synthetic haired base coat and top coat bags. Ready mixed as I don't want to waste time mixing and getting the mix wrong. 25k bags, as I am slow, so a bulk open bag runs the risk of going off before I've used it all, whereas I am using bags from 2 years ago with no problem. For value on cost of carriage I buy a pallet load at a time.

 

[Kearn]

30mm isn’t considered a thick coat for lime really.
But that mix of products and applications is frankly daft!

Most folks will reference traditional 3 coat, although I’ve found a lot of one or two coat on my historic walls.

Have a chat to a few others, try Eden Hotlime, Cornish for a start - MW can be very hit and miss with their technical advice - I’ve had some great debates on very tricky circumstances, and again similar rudimentary ones like yours.

Many modern plasterers will be able to slap it on. What they won’t understand is the right products to use where, when and why, and how to do any post application tending to make sure they don’t fail.
They also won’t factor in all the visits for each coat and intervening checking and tending to their quotes, as they’re used to getting everying done in a day and moving on.

It’s less about skills, and all about experience.

For efficiency of cost, while sealed tubs are theoretically great, they cost. Most decent suppliers will provide a ton dumpy bag of pre mix, and it lasts happily. I’ve had one of Edens on my drive constantly for the last couple of years, happily sitting there through frosts and the like and perfectly fine to knock up and get on with just a twist of the plastic bag top inside the dumpy and chunk of stone on top.

If you do go for the 20/25kg options from a supplier, aim for sealable tubs, which being easier to cart about and store, the plastic sacks from a certain supplier often turn up off the palette with nicks in them, wasting product if it’s it being used straight away.