External insulation

We have a pre-1900 semi. Solid walls. I'm thinking about having the side wall insulated externally. Won't do front or back - front would mean it would look 'out of place' in the street, also many windows. Back just too complicated - lots of windows, new extension and porch etc. The side wall though is relatively simple - few windows though it does have drainpipes and boiler flue - figure I can just avoid all those! Most of the wall insulated better than none!

Have searched forum and found only quite old posts on this, and none where anyone has actually done it - DIY or otherwise (I'm thinking otherwise).

I have found some likely materials - Wall Transform (their quotes astronomic!) and Kingspan Kooltherm K5 EWB.

Have ruled out internal insulation - too much disruption and it moves the thermal mass of the wall outside the insulation.

Does anyone have any experience along these lines.

Do your sums carefully.

To have any chance of making a worthwhile return on heat loss the insulation product will need to be significant. I know this sounds obvious but a lot of the cost is in access and providing a durable finish that won't devalue your house. Add this lot up and you might find it is either impractical or will take 150 years to get your money back.

On the other hand up you loft insulation to 300mm and you'll get your dosh back in a few years.