Yesterday our contractor finished installing new unfinished oak floors in our new kitchen and will be coming back later today to sand and stain them. When I went to look at them this morning I saw that the entire floor has been covered with wood filler that has obviously been left to dry overnight. My heart fell because the beautiful oak I saw a few days ago is now covered in a beige mess. I've watched a lot of DIY shows and I've never seen this done.

Is it usual to use wood filler like this on a new floor installation? The floorboards were nailed in the side and there should be no nail holes to fill, so I am truly puzzled. Surely the boards should be left with natural gaps to expand and contract? or if filling gaps in the boards is not the purpose is there some other reason to do this?

Also, is it usual to sand a newly installed floor? Obviously, now it has to be sanded to remove the wood filler, but I'm concerned that we are paying for an unnecessary step.

I'm really not sure what to ask my contractor when he shows up later or whether to say anything about it. Some advice would be greatly appreciated.