I'm looking to insulate the entire side elevation of my Victorian solid-brick semi-detached house... which is covered in pebbledash cement render.

 

My budget is small. Removing the pebbledash (properly) and making good is very expensive. Would it be possible to apply EWI directly to the pebbledashed walls? The house is being refurbished right now, with whole-house MVHR being installed so ventilation and internal moisture control will hopefully be adequate, but no plans to install IWI anywhere on this side elevation.

 

How would insulating over the top of the impermeable cement render affect the house? 

Yes Go straight over the existing Five holes in each sheet Bang the plastic knockins in

 

pictured is one I did over 1970s render 

Edited December 5, 20232 yr by nod

Just now, nod said:

Yes Go straight over the existing Five holes in each sheet Bang the plastic knockins in

 

Remember to 'cloak' the thermal bridge where externally-insulated walls meet internally-insulated walls. Draw an imaginary diagonal line at the end of the IWI/EWI 'junction' and you can find a path which misses both sets of insulation. Carry the IWI round a small distance (about the length of a piece of string) in such a way as it does not look stupid onto the wall which has IWI. The more you can lengthen the 'brick-to-brick path' the less critical is your thermal bridge (heat-leakage).

Thank you both, very helpful.

 

@Redbeard We will almost definitely have to live with a compromised install, without 'wrapping around' to avoid thermal bridging... due to aesthetics mainly.