Hi There, I am just about to move into our new build house. A workshop has been built for me by the main contractor (lucky I know). It is completely weather tight with rendered exterior and double glazed doors. The interior has been fitted out with OSB 3. As there is only a small window, I would like to make it lighter by painting the OSB white. My question is, what is the best primer and/or paint to use? I guess the most bomb proof solution would probably be an oil based primer and then a satin gloss but that would get really expensive. I have looked through the internet and come across lots of suggestions. Anything from just slapping on some smooth masonry paint to PVA with emulsion on top to priming with something else! I can imagine the issue with just slapping on some water based paint like emulsion is that I might swell the OSB but I'm not sure. Can anyone offer a definite solution that will not cost the earth?