We are having it installed in our 1930's red brick semi soon. It has a single story extension on the side, and during the survey I was told that the portion of old exterior wall now enclosed by the extension will still need drilling and filling. I don't see why as it's no longer outside and so can't loose heat other than into the extension which is itself heated. If I can get them to leave this wall then it would save a lot of cleaning up and redecorating afterwards.
Any thoughts ? the filling will be blown fibre which is both sticky so it stays in place and also treated against moisture.
I've already replied to this once but you obviously can't see it:
As has been mentioned on this forum before (mainly by me) blown wool CWI has to be a complete install, IE, right up to the roof, any voids in it cause damp problems, even if these voids are now 'indoors'. Yes, some builders put in a cavity tray in the house wall when building extensions, but many do not, meaning that if they tried to fill the cavity above the extension without filling below first, what's the insulation supposed to sit on? - it can't float in mid cavity so it just falls down leaving gaps all over the place. They are not filling this portion of the wall as a way of saving heat, they are filling it to prevent damp occuring in other parts of the house. Our general modus operandi was to drill each hole carefully (with the place dustsheeted up of course) and with an operative holding a shovel directly below the drill bit, tight up to the wall...usually no more than 4 or 5 holes. Each hole is then blown and then pointed up with sand/cement leaving it slightly hollow for polyfilla, a final cleanup inside will leave no more dust then you could fit on a teaspoon and 4 or 5 ten pence sized patches to fill and paint.
As an aside the blown wool is not sticky, it resembles cotton wool and is bone dry, although it is treated against moisture, this is done at manufacturing stage and is odourless.
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