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By rockwing
I rent a house with a decent-sized, triangle-roofed garage. I'll be in the property for another 3 years so happy to make some semi-permanent changes. The main issue at the moment is the gap at the bottom and sides of the up/over door which is creating mould inside. I mostly use the garage as a gym, basic woodwork and storage in the eaves.

I'm thinking of initially adding a floor threshold seal, adding some kind of seal to the frame-sides and adding insulation to the inside of the door. However would this all be fruitless if I can't insulate the ceiling? I live on the south coast so it doesn't ever get too cold, I'm more concerned about mould than the temperature.