Mortar between loose bricks before plastering

[vagrantly3893]

a couple of the bricks are loose. should I first use some mortar between the bricks and the plaster over the top?

 

[vagrantly3893]

and then plaster over the top

[Nickfromwales]

Hi. 
Get a synthetic slate, break off a couple of small pieces and then tap them in gently as packers, to hold the bricks in place whilst you make good. 
I’d use a dot & dab adhesive to patch this in, and make sure the wall is wet when you do the patching in (50/50 mix of SBR and water as a primer) so it bonds nicely to the bricks etc. 

Leave to dry and then you’re good to go. 
The wall will need priming with neat PVA for plastering and that needs to be still tacky when the plaster is applied. If you’re paying a plasterer they will already know to do this. 
With dry mortar and loose brickwork you should expect some hairline cracks to appear after plastering, which would be dealt with by filling and painting again, after this has ‘settled’.

 

Is that a concrete sill above that goes through to outside? 

[vagrantly3893]

1 minute ago, Nickfromwales said:

Hi. 
Get a synthetic slate, break off a couple of small pieces and then tap them in gently as packers, to hold the bricks in place whilst you make good. 
I’d use a dot & dab adhesive to patch this in, and make sure the wall is wet when you do the patching in (50/50 mix of SBR and water as a primer) so it bonds nicely to the bricks etc. 

Leave to dry and then you’re good to go. 
The wall will need priming with neat PVA for plastering and that needs to be still tacky when the plaster is applied. If you’re paying a plasterer they will already know to do this. 
With dry mortar and loose brickwork you should expect some hairline cracks to appear after plastering, which would be dealt with by filling and painting again, after this has ‘settled’.

 

Is that a concrete sill above that goes through to outside? 

Thanks for the detailed response. Yeah I think the sill is concrete but I'm not sure if it goes through to the outside of the wall. I'll check later.

[vagrantly3893]

Also that wall has a radiator so I wouldn't expect any issues from cold or damp

[Nickfromwales]

16 minutes ago, vagrantly3893 said:

Also that wall has a radiator so I wouldn't expect any issues from cold or damp

That's not actually how "it" works   Radiators shouldn't be on outside walls, full stop, and the fact that it's under the window keeping that area warm means that some of the heat that it produces gets lost into the wall behind it which is perpetually 'cold', so in winter you'll be probably losing 10p in the £1 or more by having the radiator in the 'wrong place' in that room.

If you could move the radiator to an interior wall then 100% of the heat it produces will go towards warming the room. Also, If this isn't a modern convector radiator then I'd suggest an upgrade. I'd certainly look at putting the reflective foil onto the wall before the radiator is put back on. Something here is better than nothing, but I'd move the radiator if you can?