Cement render or Bonding Coat for large chases left by built in furniture removal.

[axt]

Hi All,

1975 era house with a mix of Concrete block and Cinder block internal walls which I am certain were cement rendered and skim plastered originally. I have removed a lot of built in wardrobes and also cut many chases for wiring and have been filling chases to circa 2mm sub surface with Bonding plaster ready for a multi top coat. Where the wardrobes were removed, there was 2x3 battens nailed to the block work prior to rendering, so I have floor to ceiling 3 and 4" wide gaps in the render. I also have bricked some windows up a few courses.

For these larger areas (which includes a corner), is there a convention on doing them in cement render rather than Bonding plaster similar to original or Bonding plaster like usually done for chases? Similarly over 2 courses of bricks, would you normally build this out in render for strength?

All thoughts appreciated!

 

[Notch7]

You can use bonding plaster for upto 11mm thick any size area

I’ve heard if you want to do thick bonding add some cement.

You might want to coat the chases with SBR or PVA to reduce suction

 

[axt]

Thanks for the quick reply.

I have been PVAing the chases, and incidentally one other question would be that the back of the PVA bottle says to use it neat ok bonding coats, but most of the internet and DIY books say to dilute about 1:4 or 1:6, which seems more sensible? Any thoughts on that would be great - it's a thick PVA and it says to dilute for other uses but bonding coats it says to use neat...?

On the render front - it was mainly if it was better to render Vs bonding plaster for any reason? Or is it just down to which trade picked up the job, builder or plasterer!

 

[Notch7]

Thanks for the quick reply.

I have been PVAing the chases, and incidentally one other question would be that the back of the PVA bottle says to use it neat ok bonding coats, but most of the internet and DIY books say to dilute about 1:4 or 1:6, which seems more sensible? Any thoughts on that would be great - it's a thick PVA and it says to dilute for other uses but bonding coats it says to use neat...?

On the render front - it was mainly if it was better to render Vs bonding plaster for any reason? Or is it just down to which trade picked up the job, builder or plasterer!

I would add a bit of water to PVA, just enough to make it runny and easy to brush on.

In regards to render or bonding, most trades would use bonding. I keep an old bag of bonding, it’s well out of date and dries in minutes, but it’s ideal for doing the odd bit of chase filling, then I use easifill as it’s soft and easily sanded back nice and flat

It’s hard to say what a builder would use….old socks if that’s all he could find

 

[opps]

I would add a bit of water to PVA, just enough to make it runny and easy to brush on.

In regards to render or bonding, most trades would use bonding. I keep an old bag of bonding, it’s well out of date and dries in minutes, but it’s ideal for doing the odd bit of chase filling, then I use easifill as it’s soft and easily sanded back nice and flat

It’s hard to say what a builder would use….old socks if that’s all he could find

My mate, a plasterer, gave me an old bag of bonding. I patched the lower corners of a chimney breast. Once cured, I could scratch it away with my fingernail. It did however go off very quickly... He did me no favours.

 

[axt]

Yes, my bag of enthusiastically bought bonding plaster is now a few weeks past best and the multifinish - still unopened - is getting close to being past it's lifetime... Will gave to muscle the courage to have a go with it soon...

 

[axt]

Can I assume that this property, being a 1974 conventional brick built / cavity wall construction will be cement render on the inside and nothing odd like Lime rendered or a lime / cement mix render? I am thinking of having a go at rendering some larger stripes up to a few mm from existing surface to allow for a topping of multifinish but wanted to make sure doing a basic building sand / cement mix won't be an issue? Cheers...