Floating solid wood over existing floorboards.

[Big Bob]

Hello.
I'd like to float a solid wood t&g floor over existing floorboards, preferably using a sticky topped underlay such as Elastilon.
Is it mandatory that the new boards are laid at 90 degrees to the existing boards?
The room is long in relation to it's width (7m x 3.3m) and has a patio door at one end. I think it would look a bit odd with the new boards going across the short side.
I really would prefer the new boards to go lengthways. Is there anyway to make this possible?

Thanks. B B

 

[Bespoke]

Happy new year to you Big Bob

Firstly I don’t think it is very practicable to lay a floating solid timber T&G floor. There are a lot of forces released from real timber that grows on trees when it starts to settle in its new home and I don’t think that sticky back plastic will do the trick, but I hope to be proved wrong. I can see it working on clink laminate flooring but not on solid flooring were you need to get the joints up tight to allow for the shrinkage of the boards and it doesn’t seem to allow for minor adjustments. Are you thinking of using a floating floor so you will not see any fixings in the face of the floor boards or for other reasons? If it’s the former then you can fix the down using secret nailing that’s nailing through the tongue of the floor boards. Have a look at the link below and see if it will help.

www.alanwakefield.co.uk/Howtolayanoakfloor.pdf

//www.diynot.com/forums/viewtopic.php?t=85116

Regarding the direction of the floor boards this is not carved in stone but if you intending to lay the new floor in the same direction as the old then it may be better to lay 6 or 10mm plywood down on top of the old before laying the new, this will all so take out most if not all the undulations of the old floor.

There will be other replies along soon, its like waiting for a bus then 2 or 6 come along at the same time.

 

[WoodYouLike]

Hi Big Bob

How wide are your new boards and how level (i.e. not cupped) are your existing floorboards?
If new boards not wider than 180mm (preferably not wider than 160mm) you can float a solid wood floor. Elastilon is a good product and (sorry Bespoke) specially recommended for solid floorboards.

If the existing floorboards aren't level and laying straight on top of them could create a 'rocky' new floor then it's best to do as Bespoke suggested: install plywood first

 

[Big Bob]

Thanks for the replies gents.
I haven't decided on the type of board yet but will bear in mind the width. Thanks for the tip.
The existing floor appears to be really flat although on close inspection some of the boards do feel to have some curvature across their width.
Is that what is meant by cupping?
I can see that could cause some instability in the new floor if laid parallel to the existing boards.
So it would seem that the plywood is the answer?
Is there a minimum recommended thickness for the ply and how should it be fastened down?
Would laying new boards in a herringbone type patttern alieviate the need for the ply? Or would that be far to difficult to contemplate?

B.B.

 

[WoodYouLike]

Depending on the 'amount' of cupping the minimum thickness of the ply should be 6 or 8mm. If 'high' levels of cupping 12 to 18 would be needed.
The ply is screwed down.

Herringbone types of flooring definitely need a level, flat surface!

 

[Big Bob]

Thank's again WYL.
Sorry to be a PITA BUT......
I'm not sure how to relate the level of cupping to ply thickness. Obviously the worse it is the thicker the ply required.
How do i determine whether I have a high or low level of cupping.

B B

 

[mattysupra]

Another method of sorting out the cupping/crowning of boards is to hire a sander and sand the boards flat to save on raising the floor height with plywood , i always try and do this if possible but i also still install plywood over the top if not perfect. It is hard to explain what is o.k and what is not. Comes with experience really! Woody might have some sort of measurement she works to if your lucky tho!

 

[WoodYouLike]

Comes with experience really!

Same here, Matty.