Skimming chasing on lime plaster walls

DamoKen

Hi, recently moved into an old farmhouse approx 180 years old and we're getting the placed rewired next week. As we're on a really tight budget and can't afford a plasterer I'll be filling the chase lines where the electricians have laid the cabling.

I was originally planning to just use a few bags of gypsum skim, used it before for minor repairs here and there in our last house so fairly familiar working with it.

However last house was concrete walls where as this one is stone walls rendered in the original lime plaster so wondering if this could cause problems.

Could there be chemical reactions between the skim and lime?

Will the chased lines going up or down each wall stand out once finished despite a few coats of paint? Some rooms will have up to 5 chase lines, not in corners either so only thing covering them will be the plaster & paint.

Don't think breathability should be a concern as the area covered in each room with skim will be relatively insignificant to the the wall area of the entire room correct?

Cheers

BryanF

DamoKen wrote: »

n old farmhouse approx 180 years old and we're getting the placed rewired next week. As we're on a really tight budget and can't afford a plasterer I'll be filling the chase lines where the electricians have laid the cabling.
....

Don't think breathability should be a concern as the area covered in each room with skim will be relatively insignificant to the the wall area of the entire room correct?

Cheers

So your trying to use gypsum to trap moisture in the electrical chases?

Go on lime plastering course or get a professional lime plasterer in.

Or surface mount..

DamoKen

BryanF wrote: »

So your trying to use gypsum to trap moisture in the electrical chases?

That's exactly what I'm planning to do, should keep the walls nice and fresh....

Or maybe if instead of sneering you had read what I'd written correctly you would have seen I was actually asking if moisture would be a concern in such a limited area of the walls.

BryanF wrote: »

Go on lime plastering course or get a professional lime plasterer in.

Again, maybe reread what I wrote before replying.

DamoKen wrote: »

As we're on a really tight budget and can't afford a plasterer

Or better still, if you've nothing helpful to say maybe don't reply at all. You do realise the point of forums like this is people who might not have experience in different areas come seeking advice, not smart ar*e responses? Would have thought as a moderator you'd know better.

BryanF

DamoKen wrote: »

That's exactly what I'm planning to do, should keep the walls nice and fresh....

Or maybe if instead of sneering you had read what I'd written correctly you would have seen I was actually asking if moisture would be a concern in such a limited area of the walls.



Again, maybe reread what I wrote before replying.
Or better still, if you've nothing helpful to say maybe don't reply at all. You do realise the point of forums like this is people who might not have experience in different areas come seeking advice, not smart ar*e responses? Would have thought as a moderator you'd know better.

IMHO opinion not as a moderator, the gypsum will be sensitive to any moisture that would otherwise dissipate through the lime, and draw any moisture from the lime, the fact this is around electrical cables :eek:

The way the op question is phrased suggests the answer.

wayoutwest

LIme mortar/ plaster breaths and gypsum based plasters don't, so Brian is correct in pointing out that the moisture (that is likely to be rising from the probably non-dampcoursed walls) will be higher in the areas that have been replaced with the incorrect materials.By the time your chasing (which might well include having to angle grind and chisel any protruding stones) is done you could easily end up with about an inch or more to fill -so your proposed gypsum skimming would have to be preceded by infilling with bonding...which is another non-breathable material.
Mechanically, gypsum doesn't bond well with lime, and over time they often seperate, creating cracks where they join.
Also, depending on what sort of breathable paint that you intend to use, you might have problems having surfaces with different levels of absorbancy.

DamoKen

wayoutwest wrote: »

LIme mortar/ plaster breaths and gypsum based plasters don't, so Brian is correct in pointing out that the moisture (that is likely to be rising from the probably non-dampcoursed walls) will be higher in the areas that have been replaced with the incorrect materials.By the time your chasing (which might well include having to angle grind and chisel any protruding stones) is done you could easily end up with about an inch or more to fill -so your proposed gypsum skimming would have to be preceded by infilling with bonding...which is another non-breathable material.
Mechanically, gypsum doesn't bond well with lime, and over time they often seperate, creating cracks where they join.
Also, depending on what sort of breathable paint that you intend to use, you might have problems having surfaces with different levels of absorbancy.

Thanks for the detailed reply. Ok bears out the concerns I had using gypsum. So sounds like the only route really is the traditional one. To be honest it would be the preferred approach and is what we've done to date for everything. At the moment though the cost of a specialist lime plasterer is just something we can't afford so was looking for alternatives and preferably something I could do myself.

Thanks

oldbuilders2

St Astier Eco mortars are good for small patches such as chaseings. They are a readymix formulated lime has good adhesion and is a bit easier to use on small areas.