Laying engineered wooden flooring on floorboards

[google]

I'm planning to replace a carpeted floor with engineered oak wooden flooring. The "solid" floor under the carpet is wooden floorboards - this is a suspended ground floor.

A few questions for anyone with some experience in this area:

1) What underlay do I need. Will I need a damp-proof layer as well as the matting stuff?

2) Should I put a hardboard cover over the floorboards, or is it a case of taking up the carpet to see how level they are?

3) I'm a bit worried about the levels where the wooden floor will meet the hall carpet at the door of the room. The new wooden floor, together with it's various underlays/hardboard will be a fair height (I'm guessing getting on for 20mm). How do I protect/join this junction?

Thanks for any help/advice!

[rrh]

1. Whatever the floor suppliers recommend for the purpose. Doubt you will need a damp-proof layer. If a suspended timber floor is damp, better fix the damp in the first place.
2. The latter but I would still go for thin ply (5-6mm) even if I thought the boards completely flat. I recently did a suspended timber floor this way (with thinnish underlay from a roll as recommended - indeed sold - by the suppliers of the flooring) but found a very slightly bouncy patch in the middle on completion which I hadn't picked up before. If the boards are not completely flat you may want to pack the lower ones to level them up, or use thicker ply, or both.
3. Google the suppliers, buy yourself a small collection of likely-looking edgings or accessories and cut, shape and dry-fit as necessary after the floor is down to get what you want. I did this and was happy. You may waste a quid or two on unused bits but so what.

[The Natural Philosopher]

Probably not.

I would, if fr no other reason than it makes a great draught sealer.

Use a wooden threshold and make a feature of it.