Levelling uneven boards

[edmackey]

Hi there
I have a 130 yr old house with what look like (mostly) the original floor boards.
Quite a few of them have been replaced with new boards (look to be softwood), a couple are rotten, and there is a set of new boards were a fire place was taken out. The long and short of this is that I'm intending to board over them with engineered boards, rather than replace the damaged/new boards with reclaimed ones - part of this decision is due to the draft coming through now the carpet is up - gaps up to 10mm between most of the old boards!
I need to level them off in places due to discrepancies in height between old and replaced boards etc and need to know the best way to do this - just using plywood will not be sufficient.
Replacing the entire floor down to the joists is not viable due to fitted cupboards round the room that would be too expensive to replace.
Also, how much ventilation do I need to allow for when doing this and is putting grates in the floor the only way to do this?
All thoughts/suggestions welcome!
Cheers
Ed

 

[WoodYouLike]

If there isn't too much of hight differences between the various boards and you can allow to loose some height, why not install plywood first over all the existing boards? Loose the draft in the same go, but keeping the ventilation at the same time.

 

[edmackey]

Hi there - I am intending to do this, but what thickness ply do I need to use, and do I need to pack underneath it to avoid any pockets of springiness?
If so, what do I pack it with?
Cheers
Ed

 

[WoodYouLike]

Thickness of plywood depends on the uneveness and the amount of height you're willing to sacrifice, but minimum of 8mm I would say.

You could use thinner hardboard sheets (3mm) to use underneath the plywood where it appears bouncy.

 

[edmackey]

Many thanks, I will give that a bash then

Ed