Gaffar wrote:

A structural engineer spared me a couple of minutes on the phone and
advised the joists should be ok to hold the weighth of the boards
(although the celing below may crack but should not collapse), also
advised agaist screwing boards into joists if possible as they may crack
and distributing light storage weight into the sides.

Is this sound advice and is there anything you guys can think off that
may help the situation or provide reassurances. WOuld writing off the
cost of these boards be wise and just replace with ordinary loft bvoards
that can be bought in B&Q and the likes.

I don't think the issue is the boards themselves; this is more to do
with what you intend to store up there once the boards are down.

David