two of the walls on the barn I am renovating are party walls with an adjacent cottage, it sort-of wraps around the back and sides of the building, up to soffit height on the back, and full height of the gable at one end. I'm looking to mega-insulate using hemcrete and pavadentro, but, as my barn is occasional use and their house is constant use, their side of the wall will usually be warmer than mine, so insulation, per-se, is going to keep heat out, not in. I was thinking of down-grading the insulation on those walls, and upgrading on the external walls, making the insulation on the adjoining walls more sound than heat insulating... although I think this is a sensible idea, will I get away with it when I call in building control?

Posted By: jemhaywardtwo of the walls on the barn I am renovating are party walls with an adjacent cottage, it sort-of wraps around the back and sides of the building, up to soffit height on the back, and full height of the gable at one end. I'm looking to mega-insulate using hemcrete and pavadentro, but, as my barn is occasional use and their house is constant use, their side of the wall will usually be warmer than mine, so insulation, per-se, is going to keep heat out, not in. I was thinking of down-grading the insulation on those walls, and upgrading on the external walls, making the insulation on the adjoining walls more sound than heat insulating... although I think this is a sensible idea, will I get away with it when I call in building control?

Be careful. If there is a chance that the neighbouring property could be empty and unheated for an extended period during the heating season, then you could end up heating their property for them. This is especially true
if the house is poorly insulated or drafty.

If you're looking to "mega-insulate" then it may be an issue. Otherwise, it probably makes sense.

How thick is the existing party wall? if it over about 250 mm thick and generally solid with no major cracking, or gaps then the chances are it will work as is for sound.

The other option would be to build an independant timber stud frame (say 38x89 mm timber studwork wall with a 25 - 50 mm gap between the frame and the existing wall) and fill the stud voids with insulation and line with two layers of plasterboard.

That will provide adequate thermal perfromance and increased acoustic performance.


Timber