I am hoping to lay a hardwood floor on top of floorboards in my hall. The hardwood boards would lay in the same direction as the original floorboards. After watching a video on this site, it seemed to be quite straightforward, laying the hardwood on top of underlay boards. However, my wife has just come back from a flooring warehouse where she was told that you can't lay hardwood on top of floorboards and that we would have to use laminate. Is this correct? If so, what is the reason. I must say I was disappointed. I was looking forward to seeing a lovely solid oak floor in the hall. Someone else told us we might get away with it if we "secret nail" it. Is this good advice? I want to do what's best but it doesn't seem quite as straightforward as the "laying a hardwood floor" video.
I imagine it's because floors usually have all manner of gas pipes, water pipes and electrical cables running under them. When you're nailing floorboards down you have to be careful not to burst anything important, and that's easy when you can just look at the bare joists and see where all the pipes and cables are. If you were nailing a new floor on top of an old floor, you would be nailing blind and the chances of hitting something with a nail would probably be quite high. If you did have the horror of bursting a water pipe with a nail you'd then have to rip up the old floor (very quickly!) as well as the new one to get access to fix it.
Secret nailing is just a technique for laying tongue and groove floorboards by nailing through the tongues of each board at about a 45 degree angle, so that once the whole floor is laid none of the nails are visible. I'd imagine that the person who told you that was meaning that you should nail the new boards down at a shallow angle so that the nails would go through the old boards but not below them, which would remove the danger of bursting pipes and/or cables. But I don't think that's really feasible, as the new boards then wouldn't be secured as firmly as they should be, and they'd probably start to lift and come loose and squeak after a while.
Laminate would be safe as it's not nailed down, so no problems there. And some of the more expensive laminates do look very like 'real' floorboards. Most people probably couldn't tell the difference at a glance. Might be worth checking them out. But I'd say if you really want to put down 'proper' floorboards, you'd be best to lift the old floor first. Hope that helps you a bit!