Which is best - the chipboard flooring packs from B&Q which are T&G and go across the joists, or fitting thicker but non-T&G chipboard or OSB boards *along* the joists?
The boards I am looking at are 22mm chipboard I think. These thicker boards are the right width to run along the joists and my thoughts are that they'd be easy toscrew down, and thus easy to lift up to get to ceiling roses etc. They're about 1800mm long and are something like 400mm wide (joists are on 400mm centres).
The B&Q loft packs of course are designed to run orthogonally - I suppose the T&G acts as a strengthener and I have done one large loft in such a manner. But taking up a panel would mean ripping through the tongue with a circular saw set to the correct depth. They are about 1220mm long and about 325mm wide.
Costs aside (dunno the difference in costs yet). which would provide the stronger floor for a 1960s loft?