Cleaning Greenhouses/polytunnels

I had TLM one year about 3 yrs ago, for the first time in 20+ years. It was so demoralising. Most advice included cleanliness and ventilation. I got a hand steam cleaner and used that to clean the inside, together with washing with diluted J's. Bearing in mind my GH was only 8x6 it was reasonably easy if time consuming. Not had TLM again, but that statement may be tempting all the fates now.