External Wall Insulation Over Concrete Render

[rich42]

My house is 1927, solid wall with a concrete render, which needs sorting in a few places.

Is it a good idea to fit EWI directly over the render?

I have been told that the EWI boards would be mechanicaly fixed and also adesively fixed to the wall. I thought that all the render would need to be removed, but i am told this is not nessesary as it would possibly create more damage to the undelying bricks and also cost a lot!

Thanks in advance. Rich

 

[Iddy]

Do you have any problems with damp?
There shouldn't be any cement render or pointing on a solid wall. It needs to 'breathe' i.e. be water vapour permeable. - ideally the cement render would be removed along with any cement pointing, then repointed and rendered using mortar made from hot lime (non hydraulic lime putty).

 

[Iddy]

Check out the following websites:
Ty Mawr lime
Eden hot lime
Womersleys

On Facebook:
The traditional lime plastering forum
In the lime

 

[freddiemercurystwin]

Assuming the existing render is in good nick I don't see why it should be removed.