Insulation and u value

[charly]

MW its 2 cottages made into one house stone walls

Just noticed you live in France whereabouts are you ?

this pic shows you how far out i have had to come with battern insulation etc . Also told today have to do the reveals to the window with inch isulation covered plaster boards

 

[mointainwalker]

I live in the N Alps, the Tarantaise area - giant ski region. Village at 1400 m and heating from Sept 15 th to May 15 th ( dates surprisingly consistent) which is why I take a significant interest in heating and insulation.

My house has stone walls too: 900 mm ground, 600 mm first-floor and 300 mm at the top. Not good for heat-retention without a good bit o' lagging.