plywood

I'd like to insulate my concrete garage and I'm not sure if I need more insulation? Internally I plan to: 1. Paint the concrete slabs and roof with anti condensation concrete paint 2. Use DIY spray foam insulation kit on the ceiling and walls ( Link Removed ) 3. Fit plyboard 4. Fit sound...

all Just looking for some advice or ideas to cover up the attached picture situation please. Log/coal fire my mum had didn't have flexible flue installed so soot build up in chimney only discovered after painting walls. Getting flue installed now etc but the stains will continue to come...