EWI old stone wall

coffeyt

Hi hoping for some advice 're my parents property.
It's a 1800s build that was partially knocked and extended in the 1980s in such a way that the ground floor is 50% the old stone walls and 50% cavity.
The second floor is 100% cavity.

They just had a surveyor out with regards upgrading the insulation in the property under the warmer home schemes.
He advised that they can pump the cavity walls but cannot do the EWI as they no longer advise it for stone walls as he said it causes problems with the stone being unable to breath.

However last year they had a different company out under the better home schemes (before I researched and realised they could apply under the warmer home scheme). They were advised by that company that they COULD pump and do the EWI.

Obviously I don't want to advise my parents incorrectly so looking for independent advise on whether or not EWI is advisable for stone walls?

Calahonda52

http://www.josephlittlearchitects.com/articles

how smooth is the stone wall finish.
Is mortar lime based?
what is the finish on the inside face of the stone walls?
Do they have a DPC?

coffeyt

Calahonda52 wrote: »

http://www.josephlittlearchitects.com/articles

how smooth is the stone wall finish.
Is mortar lime based?
what is the finish on the inside face of the stone walls?
Do they have a DPC?

Thanks for reply will answer as best I can although neither surveyor asked any of those questions which is not instilling much confidence.
Exterior finish not smooth, more of a textured finish but not pebble dash.
Not sure on lime base.
Inside walls were standard plaster (interior hallway was drylined a few years back including a mesh between the walls and board and air vents in skirting to allow breathing)
Yes there was a damp proof course put in during the renovations.

Calahonda52

Any chance of a few picture of the outside walls.

If the"standard plaster" is a gypsum skim finish then you have a problem as it is not breathable for moisture to pass through it.
You can get breathable EWI, usually ends up with a rain shield which also helps with solar drive on the sunny aspects.
However it is not going be be as cheap as the slap and go XPS solutions.

Would the budget stretch to MHVR

coffeyt

Thanks for reply I'm assuming so the standard EWI would not be suitable as per the second surveyors advice. I had originally hoped to look at a heat pump but without the EWI I assume it wouldn't really be feasible.

A MHVR probably wouldn't be an option as its taken me 2 years to persuade my dad to allow external work happen. He has decorated the entire house himself and tbh is not really able for it anymore so doesn't want a lot of tearing and dragging inside.

They are also going to get OFCH as currently only have solid fuel so hopefully the pumping and upgrading attic insulation will make a good difference for them.