Fitting reclaimed square edge pine floorboards

[DIY Dave]

Hi all

We have knocked together two rooms on the ground floor to form a through lounge. The old floor boards taken up and the floor joists exposed. We will put PIR insulation between the joists and then screw 18mm plywood on top of the joists. The floorboards will then be held in place with cut floor brad nails (pre-drill 3mm hole in the floor boards to stop splitting) for a rustic look.
As this was two separate rooms the floor joists do not align as you pass from one part of the room to the other and we would ideally like the nails to run in straight lines across the floorboards in both parts of the room. Therefore do the nails need a joist to fix into or can they be fixed just into the plywood. If a joist is needed then we would move the joists over in one part of the room.

Thanks for any advice you can give me.

 

[Deleted member 174758]

Cut clasps/brads rarely split boards in my experience, if they are the right size - if they did then surely you would not see them in so many old buildings, would you? It's going to be hard work to nail them into plywood (especially hardwood), though, as they are really blunt. Larch ply may be a better choice as it is somewhat softer

 

[DIY Dave]

Thanks JobAndKnock regarding the choice of using softwood plywood.

The joist centres are approx. 400mm - I assume I need 18mm thick plywood and not 12mm?

 

[Deleted member 174758]

I'd say the minimum thickness for any flooring is always 18mm - 12mm is too weak and will flex.

 

[DIY Dave]

Brilliant - thanks