External wall insulation different wall types

[michaelsidcup]

Hello, I hope that despite this project being in Portugal and not the UK it is still allowed on this forum!

I own a two storey house in northern Portugal, in need of renovation, this summer I plan on installing external wall insulation. Typical houses here (like mine) have granite stone walls on the ground floor with no DPC and hollow block/brick to the first floor, the first floor walls are externally rendered. My house was extended in the 70s or 80s, the extensions has hollow blockwork to the ground floor (no DPC as far as I can see) and hollow brick (tijolo) to the first floor, all of this is then covered in a cement/sand render. At the moment the ground floor is used for storage, all living accommodation is on the first floor. My plan is to convert the GF into living accommodation at a later stage with openings subject to design and planning permission.

I have a few questions,
1. Is it possible/sensible to externally insulate just the first floor then later on, add EWI to the ground floor walls and rerender?
2. There are two materials that I would potentially be externally insulating, the rendered block/brick and the granite, I was planning on using EPS for the rendered areas then cork or wood fibre (more expensive than EPS in my area) for the granite (still a possibility to leave this exposed to retain character etc) to maintain breathability and tie it all in with a lime render. Does this make sense or happen?
3. The lack of a DPC anywhere concerns me, I think I will try to retrofit some kind of rising damp prevention with the blockwork, but is it required with the granite?

Thanks in advance, photos and more info can be given if needed. Really appreciate any help here!

 

[Mr Chibs]

Morning


Would seem a pity to cover up the granite.

Is there much/any damp on the ground floor?

What about internal wall insulation instead, you could build stud walls/tanking to take care of any damp... yes, you will loose a little internal space.

Also the ground floor presumably won't have any insulation, insulating this will make a difference, especially in comfort.


I'm envious... love Portugal, but only been as far north as Porto... looks a great house/plot, where are you near?

Chibs

 

[^woody^]

Get local advice as to what is required (regulations) and what is desirable/practical for the local climate. Also advice from specialist wall insulating firms, as it's a bit more than just fitting some random material in a random way for a random reason.

EPS is one of the most inefficient insulators. Fire spread with EPS, and internal and interstitial condensation come to mind.

Granite has no/low permeability, but the mortar may not.

A DPC is not essential.