Transitioning Nanny to Housekeeper?

Hi, we have a nanny that cares for our two children 2 and 5. Both children will be in school next year but we want to keep out nanny as we our kids are very comfortable with her.. We understand she needs full-time hours and have suggested keeping her full-time and asking to do house keeper work ie. cleaning, organizing, family laundry during the 20 hours that the kids are in school (obviously this wouldnt 100% apply when the kids were sick or off school). In terms of cleaning - what is reasonable? Thank you.