Help! laying new flooring over old joists

[robbiesnugfit]

Hello,
I'm trying to lay an new t&g oak plank floor on old existing joists. In all the web sites they suggest that the joists should be a minimum of 300mm centres for best results. My joists are 450mm centres - is this going to be a problem?
Also if the but joint at the end of the plank lands between the joists, what is the best way to support the join?
I would be gratefull for any information anyone can give,
Rob

[thedoctor]

Very unlikely to find and existing floor with 300mm centred joists Robbie and 400mm is about the norm. It depends on the thickness of the planks you have and if they are any thinner than 22mm we would not lay them on 450mm centres. The planks are always cut onto the joist so there is no overhang. See the project on the website called replacing a timber floor.

[mack4]

If the flooring is T&G all round it will be OK to lay without cutting back on the joist.To cut back will result in an inordinate amount of waste Just try to have the ends of adjacent boards on "either" side of the joists.Take it from an ex pro.
mack

Not OK at all unless you put extra noggins in to support joint Mack It wont be long before it starts springing and you will wish you did it properly.