I charge one & half times outside price ie £10 outside then £15 for inside if customers ask why is it more for inside I reel off that it takes longer, and it does ie sitting on kitchen sink to get at window or even using small steps from van putting on shoe covers, obstructions such as curtains , nets , blinds, ornaments on shelves, generally treading more carefully around their house, use to double price but always got stung 1.5 for inside a good safety net. lee