Please can someone give me some good advice! I have a converted maisonette, the old type put together poorly. The cupborad under the stairs shares the same air as the man living up stairs, gas pipes, electric etc. However, hes lovely but a heavy cannibis smoker and the smell passes through the cupborad and into my flat downstairs. I cant afford a professional, so I need to line the cupboard myself. Please can some advise me on what materials and where to start??? 
