Backing coat ???

[Dozerbull]

Hi guys
I have a few queries about the type of backing coat I should apply. There have been a couple of threads about it and I have researched it but I'm still not sure as there seems to be differences of opinions. My house was built in 1901 and I have hacked off the plaster in my daughters bedroom and I need to plaster 3 walls. 1 wall is the inside of the outside wall(cavity wall and east facing),1 is a load bearing wall and the other is a party wall.

1. Because of the age of the house I believe it is best to apply sand and cement to the outside wall but what about the other 2 walls, can I apply something like hardwall or browning. Also what depth should the s+c coat be.
2. Before I apply s+c coat do I PvA the brickwork or wet with water and if Pva do I wait until it is dry or tacky.
3. I believe it is ok to apply multifinish on top of s+c - do I wait for the s+c to completely dry or when it starts to change colour and harden and do I PGA s+c before multi finish.
cheers guys

 

[Arti]

Just hardwall all the walls. But if ya using S&C knock up a an SBR slurry coat to give the old brickwork a decent key for ya render

 

[jeanclaudevangyproc]

or 52mm thermal and fix the outside wall an hardwall the rest?

 

[johniosaif]

or 52mm thermal and fix the outside wall an hardwall the rest?

Not good for thermal mass though.

 

[johniosaif]

Personally I would scud all the walls with watery mix of 3/1 sand cement with sbr in the water , next day apply sand and cement with a mix ratio of 6/1/1 sand cement and lime with fibres in the mix, or even mesh if cracking is likely, keep slightly dampened for at least a week then skimming can start.
otherwise if their is no damp issues use hardwall after dampening the walls then skim same day.

 

[jeanclaudevangyproc]

wouldnt the room retain heat for longer if temp goes down outside?i though that was the point of thermal boards ?

 

[Dozerbull]

Thanks guys, there is no damp. Sounds like hardwall is the way to go.

 

[johniosaif]

Thanks guys, there is no damp. Sounds like hardwall is the way to go.

Lot easier and faster..

 

[johniosaif]

wouldnt the room retain heat for longer if temp goes down outside?i though that was the point of thermal boards ?

Problem inherent in thermal board is that houses were designed to get cold from outside and warm from inside (seasonly) wet from outside and dry from inside ( seasonly ) too so if you apply thermal board you remove one half of a natural faction, then the building ie bricks can fail at a faster rate due to continuously been wet/ frozen in the winter, leads to erosion and you need to be more aware of the up keep of the exterior, but alas this is not common policy , once the thermal board is applied everyone enjoys the internal heat but forgets about the outside. Not copy and paste arti

 

[Dozerbull]

Yeah I think what got me a bit confused was I had read that s+c was to be used on outside walls but only if there wasn't a cavity. I wanted to make sure of that.

 

[malc]

ffs phone a plasterer, it is not worth the aggro to try to do it your self.

 

[beddy]

S and c is cheaper and you have more time to work with it. Plus you can waterproof it to allow more time when skimming.

 

[jeanclaudevangyproc]

Problem inherent in thermal board is that houses were designed to get cold from outside and warm from inside (seasonly) wet from outside and dry from inside ( seasonly ) too so if you apply thermal board you remove one half of a natural faction, then the building ie bricks can fail at a faster rate due to continuously been wet/ frozen in the winter, leads to erosion and you need to be more aware of the up keep of the exterior, but alas this is not common policy , once the thermal board is applied everyone enjoys the internal heat but forgets about the outside. Not copy and paste arti[/QUOTE

definatley not common policy for the council they thermal every outside wall on refurbs round here now they used to limelite all the kitchens bathrooms and chimney breasts now they dont even do that all the kitchens n bathrooms ive done recently have normal themals on exterior and normal 12.5 on every other wall no treatment to brickwork nothing they simply wont pay for it they dont even want to give you pva ive seen spreads spraying walls down with water before dabbing them