would you lay engineered oak floorboards....

[IDugUpADiamond]

... on top of existing original wooden floorboards or would you ALWAYS remove existing floor first.

What do you mean by engineered floorboards - is that man made floor boards (ie mdf)?

If they are thick enough to not be affected by dips in the old floorboards then it won't matter. Also any squeaks in old boards should be fixed first.

I just know that you should lay board over old floor boards before laying carpet or the carpet will wear where there are ridges in the boards.

We are going to lay 14mm engineered oak boards on top of an insulalation layer of 3.5 mm directly on top of our old floorboards. Our architect recommended removing the floorboards, insulating and then laying 20mm engineered boards directly on floor rafters. This was much more expensive though.

Can go on top. My fella owns a floor fitting business I just asked him

However he's just said it isn't always as simple as yes or no. Other factors need to be looked into.

Thank you everyone. okeydonkey could you ask your fella about some of those factors please?

We took our existing boards up and put down the oak floorboards and had new skirting boards.

We have engineered floorboards on top of original wooden floor boards and it is fine. They just run 90 degrees to the original boards.

If existing floorboards are removed the engineering floorboards need to be thicker than 20mm.
It's also depends if you are putting onto concrete or joists..
Do you know how thick your engineering floorboards are? What is under existing floorboards?

under existing floorboards there are joists and dirt, it's very drafty

Yes. We have original floorboards with a layer of ply screwed in over the top of them. There is then a floating floor of engineered oak. (We specifically wanted to have a floating floor to reduce noise as it's in an upstairs room.)

It works well, and isn't noticeably different to walk on when compared to the engineered oak that we have stuck to a solid floor downstairs.