mingtian2014 , I strongly suggestion you stick with your installers recommendation. Especially since the new product is oil finished instead of poly. You will have two different floors going in two different color directions. If you ever decide to sell your house a buyer is not going to like that look.

If you do a complete refinish on the old floors to match the new ones yes a natural color would be currently the trend.

Installing new flooring and then sanding and refinishing all the flooring at one time will be the best match. The pre finish product will not look the same as the existing flooring. There is just a look about prefinished flooring that jumps out at me and doesn't seem to fit in well with site finished, even when the color is a close match

Thank you all for your suggestions. I will go with onsite finish. Is there anything to do with the gaps on the old floors?

Solid hardwood floors expand and contract - it is part of their charm:) If you are presently in a climate that has the heat turned on, the gaps are at their worst due to the heated dry air and may lessen during the summer.

Agree that site finished, all of them at once is the way to go. Go for a good flooring company and ask them about the old floors. If its not too big of a space it may just be worth replacing them now.

We just went through this. We had two bedrooms that had older red oak floors (1950s ranch) but wanted to extend hardwood throughout the full first floor. The picture shows the older oak in front sanded and refinished with no stain. The middle of the picture is the hallway with newly laid and site finished red oak. The back of the picture is the other bedroom with refinished old oak. The biggest difference is the spaces between the boards with the old floors, but the old and new blend well. We are very happy with the result.

Those "gaps" are mild. They are normal. They are expected. They tell the story that they are original. They are meant to be there. The new floors will eventually do that too...which means they will match (eventually). It might take a decade...but it will happen.

And don't forget that once everything is sanded down, you will be VERY surprised at how those "gaps" seem to go away (visually). Why, you ask? Because some of that is dirt. Once the floor has been sanded down (1-2mm of wood is taken off with the sanding), the dark material between the planks gets shaved off as well. And voila...they look cleaner (because they are).

Relax about the absolutely normal spacing between planks. Unless you have museum quality climate control, this LITTLE bit of shrinkage is normal and to be expected with every floor (especially if it is 30 years old).

In my opinion, a small amount of space between boards shows the character of a real wood floor. My partner and I installed 3.25 inch wide, long length oak boards in my upstairs. Super nice quality product and went in easy because there weren't boards with defects that needed to be cut out. It looks really nice but it doesn't look authentic yet. It almost looks like a created product, not a natural look that fits in to an 80 year old house.

I totally agree that the site finished is the way to go, We had ours matched to our 28 year old floors. They look perfect.

Going through this now - replaced kitchen tile with wood to match wood in rest of house and in a bit of a panic. Old floor (20 years old installed by same company) butts up to kitchen in 3 doorways and has a much more amber hue, which I was warned about. Wasn’t wanting to refinish all surrounding floors but know that would provide a better match. Applying second stain tomorrow and hoping I see an improvement. Have I made a big mistake?