To Strip or not to Strip?

[bobbyaitken]

We own a sixteenth century wooden framed, thatched cottage in Suffolk.
All of the external walls are covered with a lime rendering but have then been painted with a modern (Farrow and Ball ) exterior paint.
We believe that the paint was applied about five years ago. We are concerned that the building should not have been painted with this product and as we now want to change the colour, we don't want to repeat any errors.
Removing the paint would be a huge job.
We do not have any damp problems.
I would really do with some advice.
Thank you.

 

[L1zzy]

Hi - thought I'd pitch in before the regulars (who have much more experience than I.) if it was me though..... a.) I'd contact F&B and ask advice b.) I thought they advertised their paints as breathable (though I know others on this site think this is contentious. ) This could explain why you don't have damp issues perhaps. I'd also speak to my CO and ask his/her guidance. The thought of you trying to take all the paint off makes me think you might do more harm than good trying to do this.

My own cottage has been liberally painted with Plastic emulsion (white) outside over Stone and Lime and a bit of concrete patching. This year I am starting to take off all that I can and I will then lime wash. But any patches I can't scutch off I shall wait to blow from the surface of the stone and just lime was over the paint until this happens. My CO is happy with this approach. Good luck

 

[Nemesis]

F and B Masonry Paint says it's totally washable - nothing which says it's breathable.

 

[L1zzy]

I bow to your superior knowledge of course.

 

[Nemesis]

The long term problem may be that it affects the way the whole building breathes and the timber could deteriorate. It could be worth discussing with F and B. And SPAB.

 

[bobbyaitken]

Many thanks for the advice. Apart from the sheer scale of the job I would be concerned that removing the paint might damage the walls.
I'm temped to think that if no problems have shown in five years then we could be OK.
Wishfull thinking. If it's not one thing.....

 

[Nemesis]

I think problems could take longer to show. if damp is trapped inside walls and can't escape on a timber building it's not good. I presume that there is no exposed timber, it's all render? I'd certainly talk to F and B and see what they say, the worry is now adding more of the same...

 

[bobbyaitken]

Once again thank you for your interest. F and B don't want to talk about it. They say I should seek "specialist advice" for anything to do with lime.
And no, there are no timbers showing.

 

[skier-hughes]

Once again thank you for your interest. F and B don't want to talk about it. They say I should seek "specialist advice" for anything to do with lime.
And no, there are no timbers showing.

Odd as the manufacturers of the paint you'd have thought they'd be specialist???

Good Luck.

 

[Nemesis]

Well that's a F and B cop out! Have they no idea how breathable their paints are?

Rose of Jericho are good people - see if they have any suggestions for how to proceed and re-paint - very nice to talk to - good paints also - SPAB too.

Is there exposed timber internally?

The problem is it might be fine but it's not possible to know that, and the problems can be long term - as with cement render.

 

[Gervase]

Very few F&B paints are breathable; the majority of their range has exactly the same alkyd base as Crown and other 'non heritage' brands.
F&B has a good range of colours and is good at marketing, but the majority of its paints are not suitable for period properties, particularly for the exterior. The fact that this paint has been in place for five years without needing to be renewed or refreshed would indicate that it isn't limewash, so that rules out F&B's only external breathable finish.
Sealing moisture inside render (which is what an alkyd paint will do) is not a good idea, as that moisture will attack the framework of the building, particularly the ends of your joists buried in the masonry if you have a non-breathable internal finish. It may also damage your windowframes and lintels.
It's a problem that is likely to manifest itself in 10-15 years (unless the wood is already absolutely sodden), so the fact that nowt has happened after five years is a bit like a chap jumping from the 15th floor and saying on the way down, 'Wow, I've fallen 5 storeys and I'm unscathed!'.
I know that sounds a bit Eeyore-ish, and the chances are that your building is OK, but it makes sense to use a breathable finish if you have a lime render.
And, on top of all that, there's the satisfaction of the building looking as it should.

 

[Craig]

Slighlty off topic, but I fancy a ramble...

I have been idling away time looking at paint technical bumpf recently - trying to find one source of colour-matched oils and distempers (casein bound and "soft").

F&B is an obvious choice - but it’s frustrating that their gloss oil is an alkyd/ petroleum base rather than linseed/orange oil, etc. They also don’t seem to want to give any detailed information on the ingredients of their paint mixes and their technical performance. I like to support them as they are a local firm (down in Wimborne as is Rose of Jericho) but I wish they would move more quickly in the green direction. They do a water based eggshell but my wife likes her paint shiny!

Compare this to Aglaia, who publish all the ingredients, source and amount, and who are trying to deal with both environmental and conservation issues very openly - but its proving to be harder to get consistent colouring across the different types of paint - pity, as their linseed based gloss smells so nice, I do believe you could eat it! Aglaia give breathability/vapour absorption stats for all their paints so you can compare.

RofJ seems to be very good on the lime/distemper fronts, but again, his oils are alkyd based at the moment.

For external paint, I have had good success with Keim mineral paints on lime. Breathable and long lasting - a good Victorian invention, maybe! Its internal version is a great paint but quite rough. I think the Germans quite like the “structural grain” look…

Cant be long before oil based/VOC containing paints get banned can it?

 

[AMc]

From the Green Building Bible (yes, I've been reading it cover to cover)
"..the EU solvents directive aims to reduce the percentage of VOC's in paint by 2007 and plans to make it an absolute minumum by 2010".
Not sure what that actually means but at least it suggests an intent.

Have you actually told F&B the information you would like to see?
I would imagine that as they trade on 'heritage' then being able to supply information they have to hand to support a heritage market would be an advantage. I can see they might not want to put it in every brochure, but a fact sheet wouldn't be expensive to produce. I'm probably being niave but an email costs nothing but a few minutes of time.

 

[bobbyaitken]

F and B have now confirmed that there outdoor masonry pain is not suitable for lime rendered walls (which I kinda guessed).
My dilemma is what to do with now. It has been there for at least five years and still looks good. There is no suggestion of damp anywhere internally or externally. I am concerned as to how I would get the (acres) of paint off and what damage it might cause doing so.
Or should I just leave it?
Thanks again all. This is a great help.

 

[Penners]

All of the external walls are covered with a lime rendering.

You are absolutely sure that the rendering is lime, are you? It would shed an entirely different light on the situation if it was cement.

 

[bobbyaitken]

Hmmm. I've been told that it's lime but I dont know for sure.

 

[Penners]

I think it would be a good plan to make sure. If the rendering is cement, then it makes very little difference whether or not the exterior paint is breathable.

 

[Dave Alder]

grms/litre grams/litre
1.1.2007 1.1.2010

interior Gloss<25@60Degrees WB 75 WB 30
SB 400 SB 30
interior Gloss>25@6oDegrees WB 150 WB 100
SB 400 SB 100


Ive got the figures for the other classifications if any one needs them but these are the ones with the biggest decreases.

 

[MdB]

I think it would be a good plan to make sure. If the rendering is cement, then it makes very little difference whether or not the exterior paint is breathable.

Visually lime is whiter than cement but is there any good way of testing for sure? I guess dunking a bit in vinegar a looking for the fizz would be a good way. Does this work? Is there a better test?

 

[Penners]

In my very limited experience, it's the look and feel of the stuff that's the easiest test. Cement is - well - cement; grey hard, brittle (except, of course, when there's been a generous addition of lime to the mix, in which case it can be quite white!).

Lime is white and usually rather softer to the touch. You can sometimes see grainy bits and pieces in it, if a pozzolan such as brick dust has been added.

I'm not sure about the fizzing test. Cement (I believe) is also alkaline, so I don't know how differently the two materials would behave in acid.

Anyway, hopefully one or more of the knowledgeable lime people will give a much more expert and definite reply.