Exterior limewash on Cotswold stone

[duncanhall]

We have a Cotswold stone house, formerly a pub, with various alterations done over many years. Last year we carried out some external stone repairs and replaced the cement pointing with a lime mortar mix.

We'd now like to apply a limewash to the full exterior of the building and wondering if anyone is able to offer some advice on the following:

• Is there an ideal time to do this sort of thing? I understand we don't want it too warm to prevent drying too quickly, but equally should we avoid risk of frost?
• I've read that we should aim to leave 24 hours between coats. What if I cannot even finish 1 coat in 24 hours, will this matter?
• There are some stone mullion windows that have been poorly repaired with what looks like cement in some places, likely before the Grade II listing in the 60s. We will eventually get these properly replaced but for now will need to limewash these along with the stone. Is there any reason why this wouldn't work? Will the limewash adhere to it in the same way?
• There is still some evidence of the the historical limewash on the stone - is it necessary to remove this first, or is it good enough to brush everything down with a dry brush?
• There are some stones which are much dirtier than others due to their positioning and proximity to the road. Is it necessary to clean these first to prevent darker patches coming through the limewash?
• We'd like a pale white / slight cream colouring as this seems to be what was used on the house previously. Can anyone recommend any particular products or mixes?

Any help or recommendations on the above (or anything else!) would be much appreciated! We'd love to get this done and do it ourselves.

Image attached is the front elevation showing some of the darker stone above the door and the mullion windows to the right

Thank you!

 

[Kearn]

• Is there an ideal time to do this sort of thing? I understand we don't want it too warm to prevent drying too quickly, but equally should we avoid risk of frost?

Not yet, wait till spring. It’s a very thin lime stone coating you’re applying, it want to dry at the right rate and not have the moisture freeze and create larger ice crystals which damages the structure and binding with the substrate. Hot lime mixed in site and going in hot is more forgiving, but harder work. Although, you’ll go thicker and need 2-4 coats rather than 4-5 of a cold lime wash.

• I've read that we should aim to leave 24 hours between coats. What if I cannot even finish 1 coat in 24 hours, will this matter?

Yes, otherwise you’ll drag the first coat. You’ll see it change colour once dry, whereas in application it doesn’t look like you’ve don’t much. Don’t be tempted to overwork or add too much for that reason, you’ll get mud cracking from that.
Doesn’t matter if you don’t do it all or wait longer.

• There are some stone mullion windows that have been poorly repaired with what looks like cement in some places, likely before the Grade II listing in the 60s. We will eventually get these properly replaced but for now will need to limewash these along with the stone. Is there any reason why this wouldn't work? Will the limewash adhere to it in the same way?

You’ll probably, get adherence, but the porosity and therefore finish will be different. Trial first…

• There is still some evidence of the the historical limewash on the stone - is it necessary to remove this first, or is it good enough to brush everything down with a dry brush?

Yes, anything that brushes off remove so you have a decent substrate. Historically, like thatch, limewash just got added every year or so getting thicker and thicker…

• There are some stones which are much dirtier than others due to their positioning and proximity to the road. Is it necessary to clean these first to prevent darker patches coming through the limewash?

As long as you get any grime or other nasties off that will hamper adherence, the staining will likely not show through once you’ve got to enough coats. No issue locally doing extra coats on the stained areas if required.

• We'd like a pale white / slight cream colouring as this seems to be what was used on the house previously. Can anyone recommend any particular products or mixes?

Mix yourselves, putty and water. No point paying to ship water from a Supplier! Colour will be influenced by the colour of the lime putty and source of lime. Then you can pigment, naturally. Rose of Jericho sell pigments, but others use natural artists pigments. This is a trial and error game though, to find the right shade. Limewash can’t carry much pigment, so it’s little additional. You will also want to make sure you mix enough in one batch for the whole area per coat, as there will be variations in each mix! Might be tricky with a whole elevation….

Any help or recommendations on the above (or anything else!) would be much appreciated! We'd love to get this done and do it ourselves.



Limewash is massively forgiving and very easy to make and apply. It’s super cheap if you just buy in the putty and mix. You’ll need a decent set of brushes, it really wants to be worked into the surface, not slapped or rolled over it - you’re bonding not covering. Application is messy, the wash will be a double cream consistency, so it will splash. Eyewear essentials, plus other PPE and a clean up of spillage while wet ideally. It’s hard work, similar repetitive motions with force as plastering, so elbows and wrists will hurt. Ideal to balance left and right hands to even out the pain! And it’s slow, as you’ll ideally need 4-5 coats for first application. Plus it will need recoating - could be as much as annually, or at least every few years. So buying a decent Youngman tower will payback quickly for access now and in the future.

 

[duncanhall]

@Kearn Thank you so much, appreciate it!

The youngman tower is a good shout although we have some constraints about what/where we can put things. I'm hoping I can get this done with a decent ladder.

The main concern I have now is about protecting the surfaces after each coat, and/or once done to allow to fully cure. On limewashing, the rose of jericho site says

Newly applied exterior Limewash must be fully protected from rain, wind, direct sunlight, frost etc until it has cured and carbonated (normally about 4 weeks)

I've read about shrouding the exterior in hessian but this feel like it's perhaps getting beyond my abilities. Am I asking for trouble if I don't do this?

 

[paulc]

Colour will be influenced by the colour of the lime putty and source of lime.

I've had three different batches of lime over the years. One from Ty Mawr which had a distinct grey ting to it. Another from Mike Wye which was a brilliant white - Great if you are mixing with marble flour. My favourite to date is Singleton Birch. Has a slight hint of butter cream to it, so if you use it, you might not need to add any pigments to the mix.

 

[duncanhall]

Thanks @paulc, the Singleton Birch does sound like the kind of colour we're after so that's a great recommendation.

One thing about mixing our own wash from putty - what about the addition of casein/tallow? It sounds like these are beneficial for exterior applications in particular?

 

[paulc]

Don't quote me on this, but...
Tallow is usually added to quicklime when slaking and undergoes chemical changes due to the heat. Not heard of tallow being added to lime putty. Linseed oil is the usual additive (up to 1%).

 

[duncanhall]

Thanks, I was looking at something like this: https://roseofjericho.co.uk/product/limewash-with-tallow/

You're right, it does mention the tallow being added to hot lime so perhaps it's more about the limewash creation process.

My question really is about getting the confidence to successfully mix a decent limewash myself. Adding putty to water sounds fine. Introducing Linseed oil at a consistent quantity sounds less so, especially given I'm concerned about the fact it's unlikely I can hang hessian around my entire house for a month.

Is there a 'better' limewash between that made from putty, and that made from quicklime?

 

[jamest]

If you don't mind spending a bit more money (making your own lime wash is, let's face it, incredibly cheap) and want a bit of peace of mind, you could purchase pre-made exterior lime wash like that made by Ingilby paints. You don't need so many coats (so saves time and time is money), don't need to worry about getting your colour matched properly for different batches and don't have to worry about adding the right amount of tallow or linseed oil. I've used their Pozilime limewash and I've found it to be brilliant stuff - no need to worry about hessian sheets or anything, two coats are sufficient and it sticks to all sorts of different substrates. Costs about the same as regular emulsion paint though - about 30 quid for 5 litres.

 

[duncanhall]

Thanks @jamest - I definitely don't mind spending some more money on materials for this if it means I can actually get it done - it will still be vastly cheaper than paying someone else to do it.

That Pozilime definitely sounds intriguing as it seems like it might solve the issue of the cement 'repairs' around the windows. A quick read through their application guidelines doesn't mention a 4 week carbonation requirement either which is very encouraging!

Are there any downsides / considerations for using such a product? I'm suspicious of something that seems to be much easier than other products with the same effect?

 

[jamest]

If you're a purist, you might object to the "synthetic polymer resin" that Ingilby put in their Pozilime limewash for better adhesion. It's not in their Tallow limewash. If it bothered you, you could always give them a call and ask for details.

Earles paints also do a breathable masonry paint which has good adhesion, but contains no polymers. It's lime-based, but also contains portland cement. I've not used it though, but have heard good things - others on here may know more.

 

[Stevers]

I might be missing something, but I think that building looks lovely just the way it is!

 

[duncanhall]

Thanks @Stevers - it's definitely looking better than when we moved in 3 years ago. This photo was taken just after the cement pointing had been removed which made a big difference - but there's still a huge amount of variation in stone colour around the building, and those cement mullions really stick out. Cotswold stone really does seem to glow in the sunshine, as in the pic, but otherwise the whole exterior still looks a bit drab and I'd like to make it a bit more consistently coloured and brighter even when the sun isn't shining.

The rear of the building is very sheltered as it's set into a hill, so there is still a lot of limewash present on that part of the house and it just looks so much nicer in a more consistent creamy white colour, not to mention wanting to do whatever we can to protect the stone. After last years re-pointing I don't think we can ever afford any more stone repairs!

 

[paulc]

My question really is about getting the confidence to successfully mix a decent limewash myself. Adding putty to water sounds fine. Introducing Linseed oil at a consistent quantity sounds less so, especially given I'm concerned about the fact it's unlikely I can hang hessian around my entire house for a month.

To be honest, the proportions of putty, water, and linseed oil are not critical. I'll scoop up lime putty in a pint jug, add a glug of additives, and then give it a darned good whisk. It is only when adding pigments that you need to be reasonably accurate. But even if you get quantities spot on, there will always be a variation between one batch and another. Best to mix up more than you need (the stuff will keep for ever if stored somewhere frost free and in a sealed tub).
Mixing in artists paints, although expensive, does eliminate the chance of colour bombs when slapping the limewash on a wall.

Colour bombs are small clumps of raw pigment that didn't get dispersed in the tub when mixing.