I've just moved house and have inherited a partially finished loft/ attic space that in which the interior is clad with large sheets of unfinished plywood (nailed to the rafters). In general the build quality is very good - many joints are almost perfectly smooth and will require only minor filling and sanding. However, some of the joins between sheets are not perfectly flat, with one sheet maybe about 1mm raised above the adjacent sheet. What is the correct way of smoothing this join - I have an electric sander, but this seems too slow an approach. What should I do?
Second question is how best to finish the plywood. Ultimately I want the loft space to have an off-white painted finish. One solution is to line the plywood with plasterboard, skim plaster and then paint. However, this seems an expensive route to take and also largely pointless given the good quality of the plywood finish. I understand it is not possible to plaster direct on plywood due to flexing and cracking.
Is it sufficient to paint directly on the plywood? I understand that I need a good quality alkyl-based primer to put on the plywood before painting, and then a couple of coats of latex paint. Is this correct? Will I need to use a textured paint to hide any residual grain or joints in the wood, or is primer and regular latex sufficient?
Any tips, tricks and advice would be much appreciated!
Paul