We employ 290 full time staff and trust me we have tried Nilfisk, truvox and so on and still go back to Numatic .....You don't need Hepa for Builders cleans they over heat when running all day and there is no need for hepa... this only used for NHS or some School sites.
Also buy adding Steam you run the risk of damage to property....Good Chemicals and know how is all thats needed..