Depends what you call housework?
If it's just basic cleaning and I worked straight through, I could do a cursory basic clean of the house (quick wipe round with not too much care) in about 8 hours, just the very basic weekly tasks though, enough so I'm not embarrassed to let people in and to stop us dying of botulism! Then there's pet care on top which I don't count as housework.
However the most time consuming jobs are general tidying, laundry and ironing (ironing alone is 3 hours a week), shopping, meals. I also do the other regular too that need doing less often like gardening, washing down the woodwork, windows, mirrors, fridge, oven, cupboards, checking over the cars and topping up their tyres, oil, fluids etc, weeding out DD's clothes and room, helping with homework, playing with DD, being read to etc and I need to be home for childcare.
All in all, I reckon I only spend about 4.5 hours a day doing those things if I averaged it out.
Then in addition there's the fairly irregular jobs that sporadically take lots of time to do like decorating (just taken me a whole week of full time hours so approx 40 hours to redecorate a couple of bedrooms plus I did all the decoration and shopping for furnishings of our loft conversion).
I also do the regular weeding through the house so we don't get a build up of junk, I do the tip runs, all the ongoing repairs and maintenance I'm capable of.
As a SAHM, it's my job to do everything I'm capable of to limit hubby's household chores as he works long unpredictable hours and is often away. That way our time together is quality family time. There's no way on earth I do anything close to the huge numbers of hours he does so why should he have to to do anything? Even so, so he still will if he sees something needs doing. He also appreciates that when he has days off, they are pretty much days off but that's balanced out because I don't have days off, I just have days where I can do less.