best way to do timber floor in loungeroom

hi all
I am after some guidance and reassurance with regard to putting timber flooring down in my lounge.

this is top replace old pale pink carpet that was there when we bought the house 10 yrs ago i wasnt liked then and i still dont like it now. it is also showing the abuse of 2 young kids and a dog so its time to go.

my plan is to use 140x19 pine boards nailed to 70x19 joists which aree secured to concrete slab ( im open to suggestions best way to secure) then sand and seal the lot

this has worked well in the past in my bedroom and family room/kitchen

but i have also read about direct stick of boards to the concrete is 19mm boards the way to go or can they be thinner and then hopefully cheaper. this will also reduce the height difference between the timber and the surrounding slate
thanks in advance for any help this is my first post after watching this forum for a while so i hope to be able to help others out to sometime


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