Just chased out a channel in an old lime/hair rendered wall in order to install a cable for a picture light. What’s the best stuff to back fill this chase and cable with? I’m guessing that lime wouldn’t hold too well in a narrow chase occupied by a cable. Would it be better to use one of the modern fillers e.g. Polyfiller?
- Thread starter michael
- Start date
I've used modern filler where I've had to do this though I'm sure you could use a lime plaster mix if you wanted to.
I preferred Polycell Alabastine filler to the other variants I've tried. I was able to get a better fill and once sanded it was pretty much invisible.
I picked up a big orange box of it and Been and Queued.
http://polycell.trade-decorating.co.uk/products/info/polycell_trade_polyfilla_alabastine.jsp
I preferred Polycell Alabastine filler to the other variants I've tried. I was able to get a better fill and once sanded it was pretty much invisible.
I picked up a big orange box of it and Been and Queued.
http://polycell.trade-decorating.co.uk/products/info/polycell_trade_polyfilla_alabastine.jsp
Your cable is of course buried 50mm deep or on RCD/RCBO isn't it ?? :wink:
I would probably bulk out with lime mortar, wait for it to crack... and then finish with polyfiller. In this case, the modern stuff is made from plaster of paris (should that have a cap P?) and wood fibre so is very breathable and could almost be called a traditional material.
I would probably bulk out with lime mortar, wait for it to crack... and then finish with polyfiller. In this case, the modern stuff is made from plaster of paris (should that have a cap P?) and wood fibre so is very breathable and could almost be called a traditional material.
It is good practice to protect the new cable with a covering sleeve or, preferably, a cable conduit. The channel has to be deep enough to allow for this.
The next step is to dampen slightly the existing plaster and partly infill the chased cavity with lime plaster ( or plyfiller if you prefer) and cover the partly filled cavity, and onto the fresh plaster, an adequately cut srtip of hessian or plasterers bonding "screem". This approach will help secure the final coat of finishing plaster ( or whatever you decide to use) into position and less likely to crack or pull away from the cable protection cover.
As to what kind of plaster is more appropriate for this, it depends on then final decor finish of the room, ie- painted or wallpapered. if the choise is paint, a lime plaster finish may be more appropriate as this plaster can be worked and trowelled to a point where it could be matched to the existing.
I dont think the kind of plaster to be uised is a issue from an "historically correct" point of view for such a small area.
Middi
The next step is to dampen slightly the existing plaster and partly infill the chased cavity with lime plaster ( or plyfiller if you prefer) and cover the partly filled cavity, and onto the fresh plaster, an adequately cut srtip of hessian or plasterers bonding "screem". This approach will help secure the final coat of finishing plaster ( or whatever you decide to use) into position and less likely to crack or pull away from the cable protection cover.
As to what kind of plaster is more appropriate for this, it depends on then final decor finish of the room, ie- painted or wallpapered. if the choise is paint, a lime plaster finish may be more appropriate as this plaster can be worked and trowelled to a point where it could be matched to the existing.
I dont think the kind of plaster to be uised is a issue from an "historically correct" point of view for such a small area.
Middi
Feltwell
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For small jobs like this Gyproc Easifill takes some beating - comes in a 10kg sack that will last you for years, if kept in a rolled-down polythene sack after opening. Don't worry too much about using it all up before the best before date, my current bag is about 5 years past that date and still works fine, it just goes off a bit quick when you mix it up so you have to work fast when it's getting old.
It's cheap, very easy to mix in small amounts (I just mix it up in an old plastic measuring jug), nice and sticky but still easy to smooth, easy to sand and it doesn't shrink much whilst drying. Available from bigger B&Q's, builders merchants, etc. Re. the "2 coat" bit, that's if it's being used for it's intended use of jointing plasterboard sheets in dry-lining. You use it in the same way that you would any ordinary powder filler.
http://www.duluxdecoratorcentre.co.uk/servlet/ProductHandler?code=DDC300127
Don't bother with "Easifill 20" or "Easifill 45" unless you really want fast setting filler - the ordinary Easifill sets in a reasnoble time.
It's cheap, very easy to mix in small amounts (I just mix it up in an old plastic measuring jug), nice and sticky but still easy to smooth, easy to sand and it doesn't shrink much whilst drying. Available from bigger B&Q's, builders merchants, etc. Re. the "2 coat" bit, that's if it's being used for it's intended use of jointing plasterboard sheets in dry-lining. You use it in the same way that you would any ordinary powder filler.
http://www.duluxdecoratorcentre.co.uk/servlet/ProductHandler?code=DDC300127
Don't bother with "Easifill 20" or "Easifill 45" unless you really want fast setting filler - the ordinary Easifill sets in a reasnoble time.
JoceAndChris
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I'm reading this with interest as I'm still confused about when you need to use lime and when you don't. We're currently rewiring the future Campaign room. There are channels to fill, as well as the walls having sections to skim and around 3 square feet where the plaster has fallen off and is back to bare stone. And small dints and dings everywhere.
I chatted with the Mike Wye people yesterday and it seems we need to buy haired lime mortar, then lime plaster for the big holes? And Polyfiller for the tiny holes and channelling. And maybe a lime skim, though as the room is going to have wallpaper, a wooden apex ceiling to form a tented frame, hangings in white muslin and the walls encrusted with period weaponry I think a rough finish in places will never be noticed.
I chatted with the Mike Wye people yesterday and it seems we need to buy haired lime mortar, then lime plaster for the big holes? And Polyfiller for the tiny holes and channelling. And maybe a lime skim, though as the room is going to have wallpaper, a wooden apex ceiling to form a tented frame, hangings in white muslin and the walls encrusted with period weaponry I think a rough finish in places will never be noticed.
Feltwell
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I think it depends on how purist you want to be Joce, I'm not sure there is a "right" answer. Personally I fail to see how a narrow strip of gypsum-based filler to cover a cable chase can possibly have any meaningful effect on the overall breathability of a wall, and I have confidence that it will do the job well and won't crack, having used that method many times in the past. It's also quick and easy to do and allows you to get on with decorating, and if in the future someone doesn't like it then it's soft and easy to chip out.
Others may not agree! I also wouldn't use a powder filler on a highly damp wall, as that may cause it to fail eventually.
Others may not agree! I also wouldn't use a powder filler on a highly damp wall, as that may cause it to fail eventually.
FamilyWiggs
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On an internal wall, breathability is unlikely to be an issue anyway. You can guarantee if they'd had electrickery when they built this place, that the builders would have filled the chase in with polyfilla.
This isn't really an issue about the performance of the wall, but one of personal preference, time and cost.
This isn't really an issue about the performance of the wall, but one of personal preference, time and cost.