Furry Wall

[GK]

This lime stuff isn't all it's cracked up to be, is it? I mean, I chipped off all the cement render, oh, a few years ago, left it another year to dry out, re-pointed the outside wall with lime mortar, waited some more, lime plastered the wall late last year, then recently a couple of coats of limewash. Now the wall is sporting a beard - pretty much all over.

Other rooms which have the same treatment, apart from the colour, are perfectly ok.

 

[Moreteyne]

Don't see how you can blame the lime for this. There are external factors causing this , otherwise you would have this in all rooms.
By looking at your pics I would say your wall was saturated and is till drying out , hence the growth.
Look on the bright side , the fact that moisture is getting through means at least it isn't trapped and causing terrible damage to the fabric of the building !

 

[Gervase]

It looks like the sort of efflorescence you get with some brickwork in damp conditions. Is the 'fur' mineral or fungal in nature? I certainly doubt that it's down to the lime.

 

[oldfella]

Looks very much like salt efforescence drawn out from the dampness.

 

[Nemesis]

Extra insulation???

 

[middi]

It must be damp creeping through, it looks as if mushrooms could do well on that wall.

 

[Lime]

Isn't this saltpetre that used to be collected to make gunpowder?

 

[Gervase]

Isn't this saltpetre that used to be collected to make gunpowder?

Only if the cellar was once full of urine! As in a stable.

 

[Lime]

Isn't this saltpetre that used to be collected to make gunpowder?

Only if the cellar was once full of urine! As in a stable.

It is possible to have saltpetre without urine.

 

[Gervase]

...that'll teach me to take the p!ss!

 

[BMcD]

It certaily looks like efflorescence and is caused by the salt present in the brickwork/sand/plaster or water being dissolved and brought to the surface as the wall dries out . It can simply be brushed off and so long as the walls remain dry then it should not reoccur.

 

[Lime]

It certaily looks like efflorescence and is caused by the salt present in the brickwork/sand/plaster or water being dissolved and brought to the surface as the wall dries out . It can simply be brushed off and so long as the walls remain dry then it should not reoccur.

Brushing off the efflorescence is all you can do.

It is definite proof that the wall is still damp.
Also proof that lime lets the moisture out.
If all the rest of the house is alright then there must be a reason for this wall to be still damp.
More exposed to the weather perhaps or something leaking water into the brick somewhere?

 

[plumbers mate]

Those pics bring back memories - When I was a kid my Mam's house had an outside toilet which was (I know now!) lime rendered on the inside.
It always had furry walls and I used to sit scraping it off - well the only reading matter was the squares of newspaper and that didn't appeal to a under 9 year old!

 

[NT]

The lime plaster is taking a lot of damage from the salts as well as the bearding. If you hadnt put lime there, the bricks etc would be taking that damage instead. So the lime has prevented that. Shame to see all that handiwork mucked up. One more damp problem to fix.


NT

 

[BMcD]

Just to be pedantic

NT wrote:

The lime plaster is taking a lot of damage from the salts as well as the bearding. If you hadnt put lime there, the bricks etc would be taking that damage instead. So the lime has prevented that.

Not necessarily. The salts could have been introduced by the sand in the plaster mix. Of course you would still have the damp problem which may not have been as evident initially but could have caused more damage if left unchecked. Though you're still right to have used the lime but it is important to use well graded washed sand or river sand to help minimise the amount of salts introduced. Having said that it's more than likely the salts were already there within the masonary

 

[GK]

Well, as I said, the rest of the house has the same lime mix and same but different colour limewash on the walls. No-where else is there a problem.

'Tis a bit of a mystery. Externally it's on the North side and doesn't get any sun - and not much rain either as it's sheltered by other buildings. A water leak isn't a possibility.

The furriness is worse at waist height and almost non-existent below. The only clues are:

The external wall was once in a verandah, and all the brick work painted with impervious paint. Most of it's gone, and the joints have been raked out and partly repointed with lime.

An adjacent wall is modern with a dpc and thick cement render (not me,guv)

The floor is quarry tiles tiles laid on (probably) cement and untouched by me

I have absolutely no plans to do anything with this, it's far too late for that. I'm hoping a bit of heat will sort it out.

 

[BMcD]

Efflorescence is caused by salts within the plaster/masonary being brought to the suface by moisture drying out of the wall and as it evaporates it leaves the powdery deposit. If either the salts or the moisture are eliminated from the equation then the phenomenon will not occur and as you say the rest of the house has the same lime mix but no efflorescence then either there are no salts pressent or no dampness.
you say that one wall has the joints raked out and partially pointed. This could well be the source of water ingress or perhaps the cement render is cracked and letting water in

 

[biffvernon]

'Tis a bit of a mystery. Externally it's on the North side and doesn't get any sun - and not much rain either as it's sheltered by other buildings. A water leak isn't a possibility.

There is water in the bricks. It might have been in there a long time, from before you started work on the house, or it might have soaked in from the outside on the occasions when there was a northerly shower, or it might have got there from the inside by water vapour diffusing in and condensing where it reached the local dew point within the wall. It doesn't really matter which. Maybe it was some of each. Anyway, water being mobile stuff, will want to get out when the opportunity arises. It could go out to the fresh air or in to your room. It will first travel as liquid water by capillary action and then as vapour. In either state it will travel down the pressure gradient. On a north wall, where the sun don't shine, the vapour pressure gradient may favour movement in towards the room. Any salts will be picked up and re-precipitated on the surface as the water vapour leaves. If the room becomes drier - I guess this is what has happened in your case GK, as you have starting using the house - the water will be moving room-wards, causing the effect. The more you heat the room the faster it will happen - until the wall has run out of either water or salt. Then it will stop.

(I think.)

 

[Nemesis]

Flock wallpaper is very NOW... just consider you have an early version.