Plastering - Thermalite inner skin/existing conc. blockwork.

[Draughtsman]

There's quite a lot going on here, there was a balcony recessed into the house, (extents shown by the exposed conc. blockwork), you can see the lower extremity of a roof joist, new thermalite inner skin, roof straps etc. I still have a little patching up to do on what was exposed when the render came off the old balcony side wall.

I won't be attempting the plastering myself. I would prefer to get it wet plastered...

Any advice would be gratefully received.

 

[stevethespreader]

Not sure what advice your after but the beams need sorting

 

[Draughtsman]

I would like that wall wet plastered (and adjacent walls that are thermalite). I'm worried that just wet plastering or rendering the wall in shot, which is clearly made up of materials of differing density, would inevitably cause cracking at the interface. I was wondering if some expanded mesh might be called for here.

The small bits of exposed timber could each have similar sized polythene membrane stuck over them to debond any later render/plaster.

I don't know much about plastering and won't be doing the job myself, but I'd rather know what is involved before contacting any tradesmen.

 

[stevethespreader]

The density can be evened out with prep,you can use eml on the tiny bit of wood but as I said earlier what are you doing with the beams? You not going to board them?

 

[Draughtsman]

The beam with the visible joist hanger (top right) with the mock Tudor exposed roof joist? Yes, I was going to box in the hanger beam with plasterboard.

The existing original ceiling is plasterboard fitted 2.5" up between the lower rails of the roof joists (mock Tudor?) so that the roof beams are showing. Not sure that the Tudors used 16" ctrs but that's what the existing effect is so I continued it.

Prep? This would eliminate any potential cracking along the vertical joint between the new thermalites and old conc. blocks?

 

[stevethespreader]

I can't see any issues with it tbh once it's all prepped evened out the density of the blocks will make no diff in terms of cracking

 

[Draughtsman]

What would preparation involve? Would any special preparation at the joint between the conc. blocks and thermalites be necessary?

Would the best option on the conc. & thermalite wall be be sand/cement render and skim?

Would the thermalite only walls have the same covering?

 

[Draughtsman]

When would the wall have a coarse plaster base and then a skim, compared to a sand/cement base and skim?

I don't understand the difference between the two choices.

 

[Draughtsman]

Well, this is how it turned out